(1984) Back Matter (JNRLSE)Lincoln, Lincoln, NE 68583. 2Associate professor of agronomy, Dep. of Agronomy, Univ. of Nebraska-Lincoln, Lincoln, NE 68583-0910. 3 For information on Project

SYMPOSIAA symposium on, "Teaching Roles and Experiences for Future Teachers, was held on 17 August 1983.

at the annual meetings of the American Society of Agronomy, Crop Science Society of America, and SoilScience Society of America at Washington, DC. Some of the papers submitted for publication to theJournal of Agronomic Education are printed here to widely disseminate the information presented in thesymposium.

Pr6cis

Detroy E. Green’

Z~tE involvement of graduate students in the activi-ies and program of the Resident Education Divi-

sion of the American Society of Agronomy has beenlacking. Involving graduate students is beneficial for allinvolved in Resident Education by providing a broaderbase of ideas and philosophies. In addition, one im-portant mission of Colleges of Agriculture should be totrain the teachers of the future. The symposium wasplanned with two major objectives in mind: 1) to en-courage the involvement of graduate students in theResident Education Division and 2) to provide informa-tion about the teaching roles and experiences of Agron-omy graduate students in the various universities repre-sented.

’ Department of Agronomy, Iowa State Univ., Ames, IA 50011.

A one-day workshop fortraining teaching

assistants1

R. P. Waldren~

A 1-day workshop for teaching assistants in the Col-lege of Agriculture has been developed. The workshopuses videotapes developed for Project TEACH (Train-ing in Education of Assistants in Chemistry) as well asmaterials adapted specifically for agriculture. Topics in-clude questioning skills, reinforcement, tutoring skills,and common problems encountered by teaching as-sistants. The workshop has been hem annually for thepast 4 years and is open to both graduate and under-graduate teaching assistants.

G IRADUATE and undergraduate teaching assistantshave been, and will continue to be, an integral

part of the teaching program at most universities. Mostteaching assistants face their first attempt at teachingwith little or no experience or teaching in teaching skillsand practices; and, although usually closely supervised,this lack of expertise can be detrimental to the quality ofteaching until the assistant gains experience. In an effortto correct the lack of experience and skill of most teach-ing assistants, a l-day workshop was developed at theCollege of Agriculture in the University of Nebraska-Lincoln (UNL).

The objectives of the workshop are to allow the teach-ing assistants 1) to acquire some new ideas to use in theirteaching activities, 2) to share with others some ideasand information from their own experiences, 3) to im-prove their ability to promote student learning, 4) to de-velop an awareness of the need for continued study andpractice of educational skill, and 5) to becomeacquainted with some persons they had not known be-fore.

METHODS AND MATERIALS

120

A l-day workshop for teaching assistants in the College ofAgriculture has been held annually for the past 4 years on theFriday before classes begin the fall semester. It is sponsored bythe Instructional Improvement Committee of the College ofAgriculture and is open to both graduate and undergraduateteaching assistants in the college. Resources used in the work-shop include Videotapes developed for Project TEACH3(Training in Education for Assistants in Chemistry) and othermaterials adapted specifically for agriculture.

The schedule of the workshop is as follows:8:00--Introduction8:15--Teaching philosophy8:30--Common problems encountered in teaching

Small group discussionReport of small groupGeneral discussion

~Contribution of the Dep. of Agronomy, Univ. of Nebraska-Lincoln, Lincoln, NE 68583.

2Associate professor of agronomy, Dep. of Agronomy, Univ. ofNebraska-Lincoln, Lincoln, NE 68583-0910.

3 For information on Project TEACH materials, write the Dep. ofChemistry, Univ. of Nebraska-Lincoln, Lincoln, NE 68588-0364.

TEACHING ROLES & EXPERIENCES FOR FUTURE TEACHERS 121

10:00 Break10:20--Questioning skills

Videotape presentationSmall group discussionReport of small groupGeneral discussion

12:00--Lunch together1:00--Teaching philosophy1:20--Reinforcement in teaching


3:00--Break3:20--Ways to tutor


4:30--Adjourn

Each session on teaching philosophy includes a videotape ofa master teacher in the UNL College of Agriculture. At the be-ginning of each videotape the teacher discusses his philosophyof teaching. Each tape then shows the teacher in the classroomand/or teaching laboratory with ample opportunity for theworkshop participants to observe the teaching style of theteacher and skills and techniques used in the classroom. Thesevideotapes are designed to give the participants some insightinto how others view their roles as teachers and to reinforceconcepts and skills discussed in the workshop.

In the session on common problems, each small group isgiven a set of sample situations that teaching assistants arelikely to encounter. Some of the situations discussed includethe same student answers every question from the instructor,problems with equipment in the classroom, one studentmonopolizes class time with questions, problems with budget-ing time between teaching duties and studies, students talkingin class, and the question of dating a student in class. Aftersmall group discussion, each group reports opinions or solu-tions to the other groups and ample time is given for generaldiscussion among all the participants. Exploration of thesesituations helps set the stage for the study of teaching skillsthat follows in the workshop.

The Project TEACH videotapes are used for the sessions onquestioning skills, reinforcement, and tutoring. Each video-tape contains information about the teaching skill presentedand skits showing teaching assistants using the skill in theclassroom or laboratory, including both correct and incorrectmethods. After viewing each tape, participants discuss theapplication of the skill in their teaching assignments and reportto the other groups any aspects of the skill or its applicationthey feel needs further discussion.

Faculty that supervise teaching assistants are encouraged toattend the workshop and participate in small group discus-sions. The interaction between faculty and teaching assistantsincreases understanding of the problems and attitudes of eachgroup, and helps encourage communication throughout theacademic year.

DISCUSSION

The primary use of teaching assistants in the Collegeof Agriculture at the University of Nebraska is in teach-ing laboratories and recitations. Very few, if any, teach-ing assistants instruct lecture sections or are responsible

for writing examinations and quizzes in the courses theyteach; nor are they responsible for developing coursematerial or subject matter. Therefore, the workshopdoes not address these areas of teaching.

There have been attempts to follow the workshopwith discussion sessions later in the year in an effort toincrease interaction among the teaching assistants andfurther address problems they may be having with theirteaching duties. These efforts have failed. Teaching as-sistants tell us they are too busy and question the valueof further exploration of teaching skills. This could in-dicate a high sense of satisfaction among assistants, butit could also indicate that their teaching responsibilitiesare not a very high priority compared to other demandson their time. Additional information tleeds to begathered to fully understand the implications of this.

Evaluations of the workshop have been very positivewith over three-fourths of the participants evaluating itas excellent or very good. Some teaching assistants haverepeated the workshop. Comments from participantsshow that the workshop makes them feel that they are animportant part of the College’s teaching program. Somemodifications in the content of the workshop are madeeach year based on suggestions from the participants.

Copies of the written materials used in the workshopare available from the author.

Developing professionalattitudes with teaching

assistants1

R. H. Beck and M. A. Schmitt2

The lecture~laboratory method is used to teach "’In-troductory Soils" (Soils 101) at the University Illinois, Urbana-Champaign. The teaching team consistsof the lead instructor and four to five teaching as-sistants. The goal of the team is to provide a qualitylearning experience in soils for undergraduate students,to train graduate students in the art of teaching, to im-prove the quality of the course, and to assist the devel-opment of a professional attitude in teaching assistantsso that they believe they are an important part of theteam. Student evaluations and campus awards are ameasure of the success of the team concept. Evidencethat the teaching assistant becomes an integral part ofthe "’Introductory Soils" teaching team is reported.

I N many agronomy or soils departments, the intro-

ductory soils course has one of the largest enroll-ments and, thus, challenges the lead instructor to pre-

’ Contribution from the Univ. of Illinois, Urbana-Champaign.ZAssistant professor (present address: Dep. of Plant and Earth Sci-

ence, Univ. of Wisconsin-River Falls, River Falls, WI) and graduateresearch assistant, respectively.

122 JOURNAL OF AGRONOMIC EDUCATION

sent a quality learning experience for the undergraduatestudents (Schafer, 1975; Thien, 1973). The large classsize also provides an opportunity to train graduateteaching assistants (Hargrove and Frye, 1980) in the artof teaching (Highet, 1950).

The actual method of teaching varies with each uni-versity and college, based on the training of the lead in-structor, the expectations of administration, the amountand kind of help available to teach large enrollmentclasses, and the expectations and reactions of students.The lead instructor is responsible for determining thebest method of teaching. Fincher (1977) states twoprinciples about instruction: 1) there is no simple, bestmeans or procedure by which students learn and 2) thereis no single best method of instruction. Methods someinstructors use are the mastery approach (Foth, 1973),learning center approach (Thien, 1973), audio-tutorial(Foth et al., 1979), or a combination of approaches(Schafer, 1975; Hopper et al., 1980).

At the University of Illinois the lecture/laboratoryapproach is used to teach "Introductory Soils." Thereare problems (Roush, 1980) as well as advantages as-sociated with this most common approach. The lecture/laboratory method offers excellent opportunities and isan important component for training graduate studentsin teaching as indicated by Hargrove and Frye (1980).The use of the lecture/laboratory method requires agreat deal of coordination and teamwork between thelead instructor and graduate teaching assistants. Gradu-ate students approach the course with various levels ofability, personal experiences, preconceptions and needs.The goal is to develop a team of teaching professionalswho are effective in the classroom.

TRAINING GRADUATE STUDENTS IN THEART OF TEACHING

A primary objective in dealing with the graduateteaching assistant (TA) is to stress that teaching is an artrather than a science. There are no "sure-fire" formulasor laws to follow, although Highet (1950) stressed threecomponents of the art of teaching: preparation, com-munication, and fixing the impression. The lead instruc-tor provides the framework of the material and then en-courages each TA to use these components to become abetter artist.

Many TAs intend to use a role model image shaped bytheir own classroom experiences in their teaching oppor-tunity. Generally it can be classified as either an "ad-versary" or a "friend" role model. In the adversaryrole, the TAs feel they must know all the answers,always be in control of the discussion, and often havelofty attitudes in the classroom. The friend role, on theother hand, is characterized by "us against the lead in-structor," or "I’ll help you by providing answers to theproblem set as a favor." Teaching assistants followingthe friend role model can not or will not assume au-thority.

The University of Illinois approach requires that theTA adapt the philosophy that enthusiasm about soils is

needed and assisting the student in learning is manda-tory. When a student asks a new TA about a homeworkproblem, commonly the TA’s comment is, "I don’tknow what ’they’ want or what ’they’ mean." Our goalis to make each TA a part of the teaching team, so theattitude of "I" against "they" no longer exists. Con-verting the TAs’ preconception from "they" to "we" isthe essential ingredient.

DEVELOPING THE INTRODUCTORYSOILS TEACHING TEAM

The teaching team consists of graduate students whodesire to be TAs for several reasons. The graduate stu-dent’s advisor may require him or her to teach. Perhapsan additional appointment, 17°70 at the University ofIllinois, is the incentive. Or, graduate students maywant to enhance their teaching skills. Enhancing teach-ing skills is the objective addressed by the team ap-proach.

The course framework consists of three 1-h lectureswith one 3-h laboratory weekly. There are 15 laboratoryexercises to coordinate with the lectures, and the teammeets every week to assure that this effort is successful.Each teaching assistant is responsible for two 3-hlaboratory sections with up to 16 students per section.The first hour of each laboratory is used to prepare stu-dents for the laboratory ¢xercise; generally, it is lecture-discussion format. Quizzes are also given during thistime, and laboratory reports or past assignments are dis-cussed as well. Laboratory exercises and/or experimentsare conducted during the remaining 2 hours.

The experience level of the TA determines the amountof time he or she spends preparing, grading, and devel-oping laboratories. First-semester TAs are not expectedto spend any time developing exercises; their effort isconcentrated on developing initial teaching practices.More experienced TAs, however, are encouraged to de-velop exercises, since their teaching practices are betterorganized and more established.

The priority of the lead instructor is to motivate. Thequality of the course is enhanced if the TA shares theenthusiasm of the lead instructor. Students can quicklysense enthusiasm, and they often cite it on evaluations(Moore and Moore, 1976). New TAs need encourage-ment so that they don’t become burdened by the new ex-perience and responsibility. It is essential to spend timewith new TAs, offering encouragement and help, anddiscussing teaching strategies. Experienced TAs need tobe motivated to develop new course materials. For ex-ample, the lead instructor motivates these TAs by pro-viding assistance and ideas for slide sets, overheadseries, and new lab exercises. The lead instructor muststrive to keep all team members equally motivated.

THE CONVERSION FROM "THEY" TO "WE"

Before each semester, the team (lead instructor andTAs) meets to organize the semester. All TAs regardlessof experience, help plan the course. Each laboratory ex-


ercise is evaluated by the team, and one of four plans ofaction is suggested: 1) keep the existing exercise, 2)modify the exercise, 3) eliminate the exercise, or 4) re-place the exercise.

Based on the plan of action, TAs select three labora-tory exercise setups, with new TAs selecting the "fixed"experiments that require little or no modification, andthe experienced TAs choosing exercises that they wantto modify or replace with the lead instructor’s help.

The team being built is not typical of other teachingteams. One team approach uses several instructors, eachteaching one portion of the course (Matthews, 1978).Another team approach consists of several instructors,with the role of lead instructor rotating from semester tosemester and the other team members serving as teach-ing assistants in the introductory course while maintain-ing lead roles in other courses (McFee et al., 1980). Butthe Soils 101 team at the University of Illinois is dedi-cated to one course and its development. The lead in-structor provides the initial motivation, but in turn, thelead instructor is motivated to do a better job to keep upwith the team. The instructor and teaching assistantshave a dynamic and interactive relationship; both ap-preciate each other’s abilities.

Three major laboratory reconstructions exemplify ac-complishments of the team to improve the course:

1. Soil Genesis and Classification. Twenty-five newmonoliths have been added and, subsequently, their usein the laboratories has increased. Videotapes of fieldprofile descriptions accompany the monoliths and thishas led to an increase in the number of labs required toteach this unit. Bringing the "field" into the laboratoryhas been a useful teaching tool, which helps studentsprepare for a field trip.

2. Soil Management and Land Use. A more extensivedescription of factors affecting the Universal Soil LossEquation was incorporated into the laboratory manual.Overhead visuals were developed to teach legal land de-scription concepts and principles, and realistic andinquisitive problem sets were developed to deal withmultiple factors of land use and soil erosion equations.

3. Soil Fertility. A new laboratory was added thatdeals with fertilizer materials, covering fertilizer manu-facturing, processing and application methods. Actual"hands-on" experience with fertilizers seemed neededfor agriculture students. An accompanying slide set onapplication methods was organized. A section also wasdeveloped on nontraditional soil additives.

Because of these revisions and modifications, theSoils 101 laboratory manual has been revised three timessince 1979. The team approach toward constant devel-opment and enhancing teaching skills guarantees thecourse will continue to evolve.

DOES OUR PROGRAM WORK?

Teaching assistants agree that the teaching team ap-proach is a valuable experience. Often they requestmore exposure to teaching. Over 68o/0 of the TAs in thepast eight semesters chose to teach more than one

Table 1. Profile of teaching assistant longevity

~0Positions available in eight semesters 38 --Number of teaching assistants in eight semesters 19 100Taught more than one semester 13 68Taught more than two semesters 6 32Taught more than three semesters 2 l I

Table 2. The relationship between experience and qualityfor 19 teaching assistants.

Number of semesters taught

Teaching assistants~" 1 2 3 4 5

Number 6 7 4 1 1Number rates as excellent 0 2 2 1 1Percent rated as excellent 0 29 50 100 100

Each column in the table is mutually exclusive of any other column. For in-stance, the four teaching assistants with three semesters of experience are notincluded in the columns for either one or two semesters of experience.

semester, 32% more than two semesters, and 11% morethan three semesters (Table 1). Because the lengths individual degree programs vary, not all graduate stu-dents were able to teach as many semesters as theywould have liked. In addition to teaching the laboratorysections in Introductory Soils, the lead instructor hasencouraged TAs to enroll in teaching improvementseminars, in classes designed by the university’s Officeof Instructional Resources and in the College of Agri-culture’s Agricultural Communications courses onteaching (Everly, 1976).

Our TAs are evaluated by their students and are com-pared with TAs campuswide through the Instructor andCourse Evaluation System (ICES). To be ranked as ex-cellent, the TA must be rated by the student as eitherHigh average or High by university norm comparisonson these general questions: "Rate the instructor" and"Rate the course in general." The TA also must be inthe top 30% of those receiving such ratings. In six of thelast eight semesters the ICES form was used so thatcampuswide comparisons could be made. Forty-fivepercent of these 29 TA positions (not individuals) in sixprevious semesters received a ratfng of excellent. Thishigh rating documents some success of the teachingsystem.

There is also a relationship between experience andquality as expressed by students ratings. Table 2 showsthat none of the six TAs who taught only one semesterreceived a rating of excellent. Since the publication ofthe ratings lags by one semester, it is not believed thatratings influenced the TAs’ decision whether or not tonot teach another semester. As experience increased,however--as indicated by number of semesters taught--the percent of TAs who received excellent ratings in-creased. Personal communication with TAs who quitteaching after one or two semesters shows that theirtime commitment to research or school--not poor rat-ings--influenced their decision not to continue. There-fore, it is believed that quality and experience have astrong positive correlation.

Other indications of the success of our teaching team


are 1) two TAs were selected as finalists in the campus-wide competition for the University of Illinois Ex-cellence in Undergraduate Teaching Award, 2) oneTA was selected to receive one of two awards inthe campuswide competition for the University ofIllinois Excellence in Undergraduate Teaching Award,3) lead instructor was awarded one of three Under-graduate Instructional Improvement Grants to developnew material for the course, 4) lead instructor was twicenamed the Outstanding Teacher in Agronomy by theundergraduate agronomy students, 5) lead instructorwas named the Outstanding Instructor in the College ofAgriculture, and 6) lead instructor was selected as aof 15 finalists in the campuswide competition for theUniversity of Illinois Excellence in UndergraduateTeaching Award.

CONCLUSIONS

The teaching team has effectively used the lecture/laboratory approach to teach a continually improving"Introductory Soils" at the University of Illinois. Theteam approach helps enhance the motivation levels andteaching skills of team members while giving graduatestudents teaching experience and training. Our teamstrategy has helped us develop the professional attitudeneeded for TAs to be effective educators.

Should every graduatestudent teach?1

Steve R. Simmons2

Teaching experience has traditionally been a featureof graduate education in departments of agronomy inU.S. universities. However, a 1982 survey confirmedthat an unequal proportion of graduate students actual-ly teach as part of their graduate studies, depending onthe department. In this paper, a wider participation bygraduate students in a well-structured, positive teachingexperience is advocated. Personal benefits from theteaching experience include learning to relate to andmotivate others, improving communication skills, gain-ing confidence, and developing a better understandingof the subject matter. These benefits would be im-portant regardless of whether a student's future careerorientation is toward research, administration, or teach-ing. Results of a 1983 survey of the teaching back-grounds of agronomy department heads in U.S. uni-versities showed that teaching as a graduate student alsoinfluences future administrative attitudes toward teach-ing. High priority should be placed now on providingthe best teaching experience possible to a larger porpor-tion of our graduate student population.

1 Contribution of the Dep. of Agronomy and Plant Genetics, Univ.of Minnesota, St. Paul, MN 55108.

! Associate professor, Dep. of Agronomy and Plant Genetics.

HPHE question in the title of this article is posed toM. challenge the notion that only graduate students

headed into careers in university teaching or extensionneed and benefit from teaching experience during theirgraduate studies program. I contend that teaching ex-perience is also highly beneficial for graduate studentswho take nonteaching positions in areas such as re-search, government, and industry. Hargrove and Frye(1980) found that some department heads, faculty mem-bers, and students in agronomy believe that only stu-dents interested in university jobs need teaching experi-ence. We should question this viewpoint and examinehow graduate student teaching is important within thecontext of a total graduate studies program in agrono-my. I maintain that a well-conceived teaching experi-ence for graduate students of every career orientationwill complement the research and subject matter com-ponents of their degree programs, and will better pre-pare them for effective professional careers.

WHAT PROPORTION OF GRADUATESTUDENTS CURRENTLY TEACH?

I conducted a survey in 1982 of 44 departments ofagronomy in the United States to learn what policiesand procedures exist for graduate student teaching. Thissurvey showed that 21 of the departments (48%) have apolicy requiring or "strongly encouraging" domesticPh.D, candidates to teach at least once during theirgraduate programs. This "requirement" applies


regardless of the career objectives of the students ortheir source of support (i.e., research vs. teaching as-sistantships). At other institutions that do not requireteaching, estimates of the proportion of Ph.D. studentswho teach ranged from less than 10070 to more than90%, depending on the department. Hargrove and Frye(1980) found that only 23% of the graduate students the 45 departments of agronomy from which they re-ceived data actually obtained teaching experience.

WHY SHOULD A GREATER NUMBER OFGRADUATE STUDENTS TEACH?

This question will be approached from two perspec-tives. First, let’s consider four direct, short-term pro-fessional benefits gained by a student teacher, whetheror not his/her subsequent career involves teaching.

1. The student teacher learns to relate to and moti-vate others with diverse personalities and interests. Onething that a student teacher learns to appreciate is thelarge diversity that exists among the students in anyreasonably sized class. Potential employers of graduatestudents often emphasize the importance of possessing"people skills" in order to succeed in working withcolleagues. The experience gained from interacting withand motivating students is extremely valuable in devel-oping skills needed to work with individuals who havediverse backgrounds, interests, and personalities.

2. The student teacher improves communicationskills. Activities such as the graduate seminar andpresentation of papers at professional meetings are de-signed, in part, to improve the abilities of graduatestudents to communicate. However, the kind of com-munication experience gained in these ways is differentthan the experiences gained as a student teacher. Teach-ing involves a more spontaneous form of communica-tion. The student teacher must be flexible and some-times deviate from a predetermined plan in order toaddress student questions and correct misunderstand-ings. A graduate seminar or professional paper is oftenhighly rehearsed with little need to deviate from the pre-scribed plan. Also, there usually is a direct consequenceof communicating poorly in teaching. Students may notperform well on the examination and become frustratedand dissatisfied. This tangible "feedback" shows thestudent teacher that a communication problem exists.The student teacher then has an opportunity to discernwhy the problem exists and to take corrective action.This type of" interactive" communication is usually notavailable in other traditional graduate student com-munication experiences.

3. The student teacher gains confidence. One of theprimary objectives in graduate education is to providestudents with the skills and self-assurance to be able to"stand on their own" as they move into their careers.

4. The student teacher gains a better understandingof subject matter. It is sometimes stated that to reallyunderstand a subject one must teach it. This should be aprime motivation for any graduate student to becomeinvolved in teaching. As an example, a student who isnot necessarily interested in teaching as a career goal

might serve as a teaching assistant in a plot technique orexperimental design course to gain a better understand-ing of fundamental statistical principles. This studentwill likely become more proficient in statistics, and inthe process, may develop a greater interest in and under-standing of teaching as a career activity.

There is a second, less obvious perspective on why alarger proportion of graduate students should teach.Many of the students in graduate programs today willbecome administrators in the next 10 to 30 years. Someof them will move into academic administration posi-tions from nonteaching careers in research, govern-ment, or industry. A comprehensive teaching experienceas a graduate student can be important in providing thefirst-hand understanding of teaching a.nd its challengesthat is needed to be an effective administrator of educa-tional programs.

In order to examine this link between administrationand teaching experience as a graduate student, a surveywas conducted in 1983 of 34 agronomy departmentheads in U.S. universities. This survey evaluated the ex-tent to which these administrators had taught either asgraduate students or during their subsequent careers.Those who had taught as graduate students were askedto provide an assessment of how that teaching experi-ence had influenced their current administrative atti-tudes toward teaching in their departments.

Twenty-three of the 34 department heads (68%) hadtaught as graduate students. This experience variedamong the individual respondents, but ranged fromserving as a laboratory instructor in an introductorycourse to being responsible for teaching an entirecourse. Five of the department heads (1507o) had nottaught during their professional careers before movinginto their administrative positions, but three of thesehad taught as graduate students. These three believedthat this experience had positively contributed to theircurrent administrative attitudes toward teaching. Addi-tionally, 14 individuals who had taught both duringtheir professional careers and as graduate students alsofelt that their graduate student teaching had been im-portant. Not surprisingly, most respondents stated thatteaching as graduate students themselves had convincedthem of the desirability of achieving a wider participa-tion by graduate students in teaching. Most also madereference to the importance of their graduate studentteaching experience in gaining an understanding of thesatisfactions, rewards, and inherent difficulties in teach-ing. This understanding is needed in order to be an ef-fective administrator of teachers and teaching pro-grams. Many cited their graduate student teaching ex-perience as being important in providing an initial, earlyappreciation of the differences in teacher effectiveness,the amount of effort required to teach effectively, andthe importance of teaching as a professional activity.

CONCLUSIONS

Should every graduate student teach? I contend thatteaching experience for graduate students is much morethan just an instrument for training future agronomy


teachers. There are substantial personal and profession-al benefits to be gained by a graduate student whoteaches. These will be important regardless of theircareer orientation. A student heading into a career inresearch or industry is not justified in omitting teachingexperience from their graduate program merely because"they won't be involved in teaching". The survey of de-partment heads has shown that a significant percentageof current departmental administrators moved intothese positions from nonteaching careers. For theseheads, as well as for a majority of those who had taughtduring their careers, teaching as a graduate student wasan important factor in shaping their current administra-tive attitudes toward teaching. Thus, experiences inteaching obtained by graduate students today may in-fluence positively the administrative understanding andsupport for our teaching programs tomorrow. Weshould strive to provide a comprehensive, positive ex-perience for a wider sector of our graduate studentpopulation. This is in the best interest of developingPh.D, graduates who will be effective agronomy pro-fessionals in research, teaching and administration.

The Minnesota graduatestudent teaching

practicum1

J. M. Hanft, J. G. Lauer, and S. R. Simmons2

In 1980, the Agronomy Department at the Universityof Minnesota initiated a teaching practicum course.This course enables graduate students to participate indiscussions pertaining to various aspects of teaching andalso assists them in formulating a personal teachingphilosophy. Course objectives include developing apositive attitude towards classroom or extension teach-ing as a professional activity and encouraging pursuit ofteaching excellence. Graduate students gain experiencein teaching by assisting in one of the departmentcourses, or by conducting an extension project with anagronomy extension specialist as their advisor. Studentsalso gain experience with specific teaching methodsusing a microteaching approach. Based on surveys ofparticipants in the teaching course from 1980-1982, itwas found that the teaching practicum succeeded inachieving these objectives by offering students a broadrange of teaching experiences. Former students ex-pressed a desire for more critical evaluation of theirclassroom performance. The success of this teachingcourse over the past 3 years indicates that it may serveas a model approach to providing graduate studentswith a positive teaching experience.

' I 'tiACHER training is an essential feature of agron-A omy graduate education (1,2). Hargrove and Frye

(2) found in a survey that many agronomy departmentheads, faculty, and graduate students agree that teachertraining in agronomy could and should be improved, al-though specific department level programs for improv-ing teacher training are rare. White (3) describes agraduate level teacher training practicum in agriculturaleconomics that incorporates both instruction in teach-ing and practical teaching experience.

The Department of Agronomy and Plant Genetics atthe University of Minnesota offers a teaching practicumentitled "Supervised Teaching Experience in Agrono-my" (Agro 8000) for graduate students interested ingaining teaching experience as part of their graduatestudies. Graduate students enrolled in the course gainteaching experience by either assisting in one of the de-partment's agronomy or plant breeding courses, or byconducting an extension teaching project. Students alsoparticipate in a series of discussions concerning themechanics and philosophy of teaching. Agro 8000 pro-vides a structure for orienting graduate students, re-gardless of their career goals, to many of the issues,methods, and skills needed to effectively teach in a de-partment of agronomy. The course also helps partici-pants develop a positive appreciation for teaching as acareer activity. Agro 8000 may serve as a useful modelfor other institutions that wish to develop or improvethe graduate student teaching component of theirgraduate agronomy program. This article describes andevaluates Agro 8000, particularly from the graduate stu-dent's perspective, and offers some conclusions regard-ing the effectiveness of such a practicum.

AGRO 8000: HISTORY AND DESCRIPTION

Agro 8000 was added to the Agronomy and PlantGenetics graduate curriculum in 1980 to provide gradu-ate students with a way to structure and documentteaching experience as part of their graduate studiesprogram. Agro 8000 is organized on the basis of thefollowing four postulates:

1. The course should concentrate on actual teachingactivities with opportunities for constructive critique ofstudent efforts, discussion of both teaching mechanicsand philosophy, and should encourage student self-improvement.

2. Graduate students are knowledgeable about teach-ing, whether they realize it or not, because of their manyyears of experience as students under various teachersand educational methods. Thus, instructional sessionsorganized for the course participants should emphasizediscussions or microteaching exercises that maximizeactive student participation.

3. Faculty participants in the course should be in-dividuals respected by the students as teachers.

4. Faculty from outside the department should be in-cluded as resources in the course.

1 Contribution from the Dep. of Agronomy and Plant Genetics,Univ. of Minnesota, St. Paul, MN55108.

1 Graduate research assistants and associate professor, respectively.


There are three major components of Agro 8000:actual supervised classroom or extension teaching, in-struction in the teaching mechanics needed by a begin-ning teacher in agronomy, and a forum that encouragesthe students to improve their teaching skills and to de-velop a personal teaching philosophy. The studentsteach in a departmental course or with an extensionspecialist of their choice. The student teacher’s specificresponsibilities are defined in advance with their super-vising instructor or extension specialist. The specific ex-perience varies depending on the type of course in whichthe graduate student assists. With either the classroomor extension option, the student participates with theother students registered for Agro 8000 in weekly 2-hdiscussions during the fall term. These discussions focuson both the mechanics and philosophies of teaching.During the term that students actually teach they meetregularly with both their supervising instructor as wellas with the Agro 8000 instructor. These sessions providethe students with the opportunity to obtain instructionand support while they are actively involved in teachingactivities. In these sessions the students may decide toexperiment with alternative teaching methods, developstrategies for dealing with problems encountered in theclassroom, or obtain counsel on handling student-teacher relationship problems.

The weekly teaching discussions held during the fallterm provide a time for free exchange of teachingphilosophies and ideas, and for helping students gain anunderstanding of the basic mechanics of teaching in aclassroom or extension environment. For many of thesesessions, the students have assignments that relate totheir actual classroom or extension teaching experience(Table 1). Table 1 presents the discussion topics forAgro 8000 in 1983. Six of the discussion topics listed inTable 1 involve participation by faculty in addition tothe Agro 8000 course instructor. These include personsfrom outside the department. For example, "What isgood teaching?" includes two outstanding teachers (oneof whom is often from another department) identifiedby the participating graduate students.

EVALUATION OF AGRO 8000: THE GRADUATESTUDENTS’ PERSPECTIVE

The primary objective in evaluating Agro 8000 was todetermine how well the course is achieving its originalpurpose of encouraging good teaching practices and de-veloping positive attitudes towards teaching as a careeractivity. The other objectives were to:

1. Evaluate the actual experiences gained from theteaching components of Agro 8000.

2. Evaluate the discussion component of Agro 8000.3. Assess the influence that Agro 8000 has had on the

careers of students who have graduated since complet-ing the practicum.

We used two different surveys as sources of data toevaluate Agro 8000. One was the course evaluationforms distributed to the participants by the Agro 8000instructor and completed immediately upon completionof Agro 8000. We used these forms to evaluate the dis-

Table 1. Agro 8000 fall discussion topics, formats, and assignments.

Topic Format and assignment

What is good teaching?

Motivating students to learn.

Planning a course.

Evaluation and writing exams.

Lecture method.

Student/teacher relationship.Discussion and other alternatives

to lecture.

Extension teaching.Evaluating and improving your

teaching.

Discussion with two effective teachers(identified by Agro 8000 students).

Discussion with guest resource person fromoutside department.

Students prepare course outline and proce-dures.

Students write and critique exam questions.Guest resource person.

Students prepare and present microlecture;critiqued by instructor and peers.

Discussion with guest resource person.Students prepare and present microdiscus-

sion or assignment; critiqued by instruc-tor and peers.

Discussion with guest resource person.Discussion with guest resource person.

Table 2. Value of Agro 8000 course components and specificdiscussion topics as assessed by the course evaluations

(1950-1982).

Mean value StandardCourse component ratingS" deviation

Overall teaching discussions 5.5 0.7What is good teaching? 5.9 0.9Motivating students to learn 5.0 1.2Course planning 5.1 0.8Evaluation and exams 5.3 1.2Lecture method 4.6 1.1Student/teacher relations 5.0 1.0Discussion method 4.9 0.9Extension teaching 5.2 1.0

Overall teaching experience 4.9 0.8

Rating scale: 1 = very poor, 2 = poor, 3 = fair, 4 = good, 5 = very good,6 = excellent, 7 = exceptional.

cussion topics and the teaching/extension experience.We also distributed a follow-up survey to all partici-

pants who have completed the practicum since 1980.With this survey, we assessed the participants’ longer-term view of their teaching experience and determinedhow Agro 8000 has influenced career choice and jobperformance.

Table 2 summarizes the results of the course evalua-tions. Participants were asked tO rate each componentaccording to the scale presented in the legend of thetable. Overall, the discussion component of Agro 8000was rated somewhat higher than the actual teachingcomponent. The discussion topic entitled "What isgood teaching?" received the highest rating. We at-tribute the high rating for this session in part to the in-volvement of faculty who the students identified ashighly effective teachers. Accordingly, these instructorspossessed the credibility to discuss teaching with thesestudents. The other discussions received a very good orbetter rating. The topics concerned mostly with themechanics of teaching, such as "Lecture method" or"Discussion method," were generally rated lower thantopics concerned more with philosophy of teaching suchas "Motivating students to learn." In more recent offer-ings of the course, the discussions concerning teachingmechanics have become more student oriented.Students now gain from peer and instructor critique ofmicroteach exercises where they develop and present a


Table 3. Participation by student teachers in classroom andextension options of Agro 8000 (1980-1982).

Table 5. Value of Agro 8000 experiences assessed from the follow-upsurvey of former Agro 8000 participants (1980-1982).

Percent of Mean value StandardOption student teachers Experience ratingS" deviation

Classroom options 90lntro to plant breeding 21Principles of plant breeding 7Cytogenetics 17Field plot design 21Weed control 7Morphology, identification of crops, weeds 7Growth, development, culture, field crops 7Adaptation, distribution, production, field crops 3

Extension option 10

Overall teaching/extension experience 4.9 1.0Meeting with supervising instructor 4.9 0.9Meeting with Agro 8000 instructor 5.0 0.9Writing philosophy statement 4.6 1.4Seminar as method of teacher training 3.4 1.5Agro 8000 as method of teacher training 5.2 1.0Agro 8000 in improving communication skills 4.3 1.2Agro 8000 in job training 4.7 1.5

Rating scale: 1 = very poor, 2 = poor, 3 = fair, 4 = good, 5 = very good,6 = excellent, 7 = exceptional.

Table 4. Responsibilitiel~ of student teachers in the classroomoption of Agro 8000 (1980-1982).

Percent ofStudent teacher responsibilities student teachers

Lecturer 52Lab instructor 35Discussion leader 35Question writer 38Grader 23Videotaper 14Tutor 35

lecture or discussion for the rest of the class. The valueand interest in these topics have increased since studentparticipation was expanded.

The follow-up survey was sent to all 32 individualswho have completed the course since 1980. Twenty-nineof the participants responded. Eight of these had gradu-ated and were employed at the time the survey was con-ducted. Of these eight graduates, two were teaching,two were extension agronomists, and all were involvedin agronomic research.

Table 3 shows that Agro 8000 participants in theclassroom teaching option have assisted in eight coursesin the department. The greatest involvement was inthe introductory plant breeding course and the under-graduate field plot design course. Ten percent of therespondents chose the extension option for their teach-ing experience.

Table 4 lists the kinds of teaching responsibilitiescourse participants had in the courses in which they as-sisted. Responsibilities differed depending on thecourse, but more than half of the respondents lecturedas part of their teaching experience. Over one-third ofthe student teachers wrote questions for exams and as-signments, were lab instructors or recitation leaders, ortutored individual students. Table 4 shows that studentsenrolled in Agro 8000 gained teaching experience in abroad array of instructional situations.

Table 5 summarizes the evaluations of Agro 8000 pro-vided by the follow-up survey of former students in thecourse. Participants gave the overall teaching/extensionexperience a very good rating, which agrees with therating given to this component of Agro 8000 imediatelyafter completing the practicum (Table 2). Other experi-ences that were rated very good included meeting withthe supervising instructor and the Agro 8000 course co-ordinator, and writing a teaching philosophy statement

upon completion of the course. Respondents rated Agro8000 as a good way to improve their communicationskills, although this rating was lower than other experi-ences. Agro 8000 was rated substantially higher thangraduate seminar as a method of teacher training. Tworespondents commented that the seminar was not agood method of teacher training because it did notinvolve enough interaction with the audience. Twoother respondents felt that a seminar format is tooformal and structured for the classroom.

Graduates that participated in Agro 8000 said that thecourse helped train them for their current jobs. One in-dividual felt that Agro 8000 offered a good chance tothink about teaching before accepting a position that in-volved teaching. Another respondent said, "AfterAgronomy 8000, I will look upon teaching responsibili-ties as a positive aspect of a job." About one-third ofrespondents that have graduated said that Agro 8000 in-fluenced their job choice.

Participants were also asked to list the most valuableexperiences gained from the course. One respondentsaid that, "...talking with good teachers about howand why they teach was a valuable aspect of thecourse." Another participant wrote, "The teaching ex-perience was the most valuable in that it exposed me tothe nitty-gritty of teaching at the college level." A thirdprticipant believed that the most valuable experiencegained from Agro 8000 was, "...learning that I didn’twant to teach."

Former participants were also asked to comment onhow Agro 8000 might be improved. Most commonly,survey respondents desired a more critical evaluation oftheir teaching by both their supervising instructor withwhom they taught and the Agro 8000 course instructor.The microteaching experiences and regularly scheduledmeetings with the Agro 8000 instructor during thequarter of teaching (Table 5) are recent modificationsin the course which should provide greater opportunitiesfor evaluating participants’ teaching performances. Allparticipants who responded to the survey said that theywould recommend Agro 8000 to other graduate stu-dents.

CONCLUSIONS

We conclude that Agro 8000 has succeeded inachieving its objective of providing a meaningful ex-


perience and understanding of teaching as part of thegraduate studies program in agronomy and plant breed-ing. Participants were offered a broad range of teachingexperiences both in subject matter and in method. Agro8000 students expressed a desire for a more criticalevaluation of classroom performance. Course modifica-tions instituted in 1983 will assist the course instructorsand the Agro 8000 instructor in evaluating the studentteacher's performance more thoroughly and direct thefocus of discussions toward critiquing the students.

Agro 8000 has been offered at the university for just 4years. We have attempted to provide a short-termglimpse of its effectiveness to date. From this perspec-tive, Agro 8000 appears to be a useful model for devel-oping a department level teaching practicum for gradu-ate studies in agronomy.

Teaching experiences ofcrop science teaching

assistants atIowa State University1

B. D. McBratney and D. J. Cox2

Crop science teaching assistants (TAs) in the Agrono-my Department at Iowa State University receive a vari-ety of experiences in teaching. The TAs are responsiblefor assisting in the "Introductory Crop Production"course and for teaching conventional laboratories. Inaddition, TAs may receive experience in upper-levelundergraduate courses. These experiences encompassvarious teaching methods, such as involvement withguided self-study classes, conventional lecture, lecture-discussion, or all three formats. The TAs are given theopportunity to develop and display teaching materialand to prepare and evaluate test questions. In additionto these experiences, the College of Agriculture offersseveral formal courses for beginning teachers which TAstake to improve their teaching skills.

Table 1. Formal courses taught by the Agricultural EducationDepartment, College of Agriculture, Iowa State University.

Course Description

'Journal Paper no. J-66, College of Agric., Iowa State Univ.,Ames.IA 50011.

2 Former adjunct instructor (Presently wheat breeder, Pioneer Hi-Bred Int., Hutchinson, KS 67501) and former teaching assistant(Presently assistant professor, North Dakota State Univ., Fargo, ND58105), Dep. of Agronomy, Iowa State Univ., respectively.

Instruction and OrganizationalProblems of BeginningTeachers of AgriculturalEducation

Organizing Agricultural In-formation for Class, Pro-fessional, and ScientificMeetings

Instructional Methods forTeaching in AgriculturalEducation

Seminar in AgriculturalEducation

Teaching Assistants OrientationSeminar

Problems in instructural planning andmethodology and in organizing agricul-tural experience programs

Concepts and practices in planning, prepar-ing, and presenting materials used in classand meetings by agriculturalists

Innovations and advanced principles inteaching methods and materials

Reports and discussion of recent literatureand research

Survey of basic techniques of college teach-ing for graduate teaching assistants.Videotaped microteaching experiencesemphasizing methods of lecturing, con-ducting discussion, questioning and re-inforcement are included, as well assimple media production and classroomtesting and evaluation

' I ^E crop science teaching assistant (TA) is providedA a variety of experiences while teaching in the

Agronomy Department at Iowa State University. Inaddition, the Agricultural Education Department in theCollege of Agriculture offers several formal courses(Table 1) to instruct beginning teachers how to prepareclass materials and instruct undergraduate students. TheTAs take these courses to improve their teaching skills.

Graduate students on appointment in the AgronomyDepartment have either research or teaching responsi-bilities. The fact that TAs do not dilute their effortswith a heavy load of research responsibilities enables theTA to develop teaching proficiency and allows for highquality classroom instruction for undergraduates. Re-search assistants are not required to teach, but with theconsent of their major professor and a member of theteaching staff, they may teach one or more semesters intheir area of interest.

Half-time crop science TAs spend approximately 9 h/week teaching. During their first semester, TAs spendtime in an audio-tutorial (Postlethwait, 1967; Green etal., 1973) learning center teaching the "Principles ofCrop Production" course (Table 2). In addition to thesehours, the TA spends 9 to 10 h learning the subjectmatter of this course and 4 h learning the subject matterfor the grain-forage crop production laboratory theywill teach their second semester. As TAs become moreexperienced, they assist in different upper-level under-graduate courses.

TEACHING EXPERIENCES

In the audio-tutorial learning center, TAs are able tocommunicate thoughts and ideas to individual students.It is essential the TAs be well versed in the subjectmatter to create good teacher-student interaction. Toaid in student learning and understanding, TAs are en-couraged to develop teaching material for display. For


Table 2. Agronomy courses in which crop science teaching assistantshave involvement at Iowa State University.

Course Description

Principles of Crop Production

Grain and Forage Crops

Crop Quality, Utilization,and Evaluation

Seed Production

Principles of Crop Physiology

Crop and Seed IdentificationLaboratory

Intercollegiate Crop Identification,Seed Analysis and Grain Grading

Chemical Use in Crop Productionand Soil Management

Crop Management

Introduction to Plant Breeding

Introductory principles of plant-soil-climaterelationships in crop production

Production and management practices forcorn, soybean, small grain, and foragecrops common to midwest agriculture

A survey of various uses of agronomic crops

Study of major seed production areas; en-vironmental and physiological factors af-fecting production and management ofseed crops

Basic principles concerning the growth, de-velopment, and production of crop com-munities in relation to their environment

Identification, agronomic and binomialclassification of crops, weeds, and diseases

Intensive training for competition in inter-collegiate crops contests

Managerial, physiological, and ecologicaleffects of chemicals applied to crops andsoils

Synthesis of crop management systems andpractices using the principles of agronom-ic science

Basic principles used in genetic improve-ment of plants

example, plant demonstrations and posters explaining atopic may be developed to guide student learning(George and Pepper, 1972).

Students enrolled in the audio-tutorial class may beassigned to a discussion section led by a TA (Foth et al.,1979). From this experience, TAs learn to develop prac-tical application examples of the subject matter studentspreviously learned in the audio-tutorial learning center.Hypothetical situations are developed for the students,and then a discussion ensues on possible approaches tosolving the problem. The TAs' main concern in thislearning environment is to create a student-centeredrather than teacher-centered discussion.

The first feeling of complete responsibility for a classfor most TAs comes when teaching a conventionallaboratory. In the audio-tutorial setting, a TA primarilydeals with individual students; however, in the con-ventional laboratory, TAs must also develop the skillsneeded to lead group interaction. Each week the TAprepares and presents a short introduction to thematerial to be studied. The development and evaluationof a quiz over the material helps the TA develop testwriting skills.

The TAs may help professors in upper-level courses inaddition to the responsibility of teaching in the audio-tutorial learning center and laboratory courses. The firstsuch experience may be the opportunity to presentseveral lectures in a conventional lecture setting. For theTA this means a role reversal, because the TA is ac-customed to being on the other side of the podium as astudent. Therefore, it is essential to develop a comfort-able mode of lecturing and communication withstudents. The TA must determine whether lecturingwith emphasis on principles or a problem solving ap-proach gives the best lecturer-student interaction(Kozmaetal., 1978).

A teaching experience available in another course isthe use of the lecture-discussion format. Here, the lec-ture and discussion are based on a set of study questions(O'Connor, 1973). The students use the study questionsas guides to preclass learning. These study questions areused by the TA to lecture, encourage class discussion,and maintain continuity. In this course it is essentialthat the lecturer be prepared to maintain a lively discus-sion.

The TAs also may be involved in a guided, self-studycourse that meets weekly with students to discuss the as-signment and talk about the principles which should belearned. The TAs help direct student study outside theclassroom. They soon learn what material students canand cannot readily learn in the classroom. The TAs areencouraged to organize, develop, and design self-guidedstudy material to allow students to receive "hands-on"experience.

DEVELOPMENT OF TEACHING MATERIALS

When developing teaching materials, TAs learn thatthere are important questions to keep in mind (Leonardet al., 1972). First, can students comprehend the ideasfrom the study material? Secondly, in which ordershould it be presented? Maintaining the material in alogical order is paramount to a conventional laboratoryutilizing posters to illustrate concepts. Next, are keypoints emphasized? Teaching material should be de-signed so students do not have to search for key points;rather, the key points should be highlighted. Finally,when developing material, ask, "Can relationships bedrawn from the material developed?" If the relation-ships are not somewhat obvious, students are unlikely todiscover them.

TESTING

Another aspect in which valuable experience is gainedby TAs is testing. Tests must be written for many of thecourses in which the TAs assist. From testing andquizzing, TAs learn what the student is learning and notlearning (Troeh and Frederick, 1973). Then, TAs areable to evaluate and improve teaching materials, varyteaching methods, reorganize the message, and/or selectdifferent points to stress. It soon becomes evident that itis difficult to write challenging test questions that arecorrectly interpreted by the student. If questions arepoorly written, the student becomes confused andmisses the fundamental principles being stressed. Fromexperiences in testing, TAs also learn test formats, dif-ferent types of questions that may be asked (eg.,memory or application), and methods of evaluating stu-dent performance (Drawbaugh and Hull, 1971).

EVALUATION

Each Friday during the academic year the TAs andprofessors meet to discuss problems that occurredduring the week. Therefore, TAs are directly evaluatedby their peers and professors. The TAs are also evalu-


ated by students. Students evaluate those TAs teachingthe crop production discussions and the conventionallaboratories. These evaluations are computer scored,and feedback is given to the TA.

SUMMARY

Crop science TAs in the Agronomy Department atIowa State University receive a variety of teaching ex-periences. The TAs first receive teaching experience byspending time in an audio-tutorial learning center teach-ing a crop production course. After a semester in thelearning center, TAs also become responsible for teach-ing a grain and forage crops laboratory. As TAs becomemore experienced, they may also assist professors inupper-level undergraduate courses. The TAs learn to de-velop teaching material and test writing skills. To de-velop teaching skills, TAs take several formal coursesoffered by the Agricultural Education Department.These teaching experiences have helped TAs developthemselves as persons and as professionals, and havehelped former TAs decide which teaching method(s) arebest suited to their individual style and students' needs.

PROFILESThis new section of the Journal of Agronomic Education presents articles on outstanding individuals

and their contribution to the agronomic, crop, and soil sciences. The biographies are written by pro-fessionals knowledgeable about the work and background of the individuals. Profiles emerged as an ideafor a section of Journal of Agronomic Education after members of the editorial board read the Profilessection in the Journal of Chemical Education, a part that describes outstanding chemists. The editorialboard solicits readers’ views of this section and ideas for future biographies.

The first Profile describes the life and research activities of Dr. Roger Bray, a soil scientist best knownfor his development of the Bray P-1 phosphorus test. The author of this Profile, Dr. L. T. Kurtz, EmeritusProfessor at the University of Illinois, summarizes some of the early soil testing procedures and philoso-phies, notes Bray’s contributions to the changing field, and concludes with some biographical notesconcerning Bray’s education and experiences.

W. A. AndersonEditor

R. H. Bray and therequirements for a

successful soil test

L. T. Kurtz’

During the infancy of agricultural chemistry, in-formation and experience were very limited. Tech-niques, equipment, and analytical methods were veryrudimentary. Decisions on how problems should besolved or even on what data to collect were often madeby arbitrary or intuitive reasoning by the experts. It isnot surprising that some efforts were misguided. At-tempts to use chemistry to improve the soil as a mediumfor crop production were begun even before the es-sential elements for plant growth were well identifiedand also before the periodic table of the chemical ele-ments was organized.

Whether intended or not, Liebig’s work during themiddle of the 1800s fostered an era of total chemicalanalysis of soils. It was believed such analyses wouldsupply the information needed for interpretations aboutcrop nutrition and fertilizer use. This belief continuedfor many years under the assumption that the chemicalelements required for plant growth would be moreabundant in the more productive soils.

Gradually, total elemental chemical analyses becamerecognized as being insensitive and unsatisfactory for

’Professor, Emeritus, Dep. of Agronomy, Univ. of Illinois,Urbana, IL.

132

revealing the adequacy of a soil to supply nutrients tocrops. A great proportion of the soil is virtually inert asfar as crop growth in one season is concerned. It is prac-tically impossible to analyze this bulk of inert materialand measure variations in the small amounts of activeplant nutrients that determine crop growth.

By 1894 Dyer, a British soil scientist, had recognizedthat total analyses of soils were of little help in estimat-ing crop growth and proposed an extracting solutionthat he hoped would imitate the plant in removing nutri-ents from the soil. As time went on, the use of totalanalysis to assess soil fertility declined; other scientistsproposed reagents that they hoped would remove fromthe soil the same nutrients that the plant could take up.An era began when the chemical methods for soil testingwere designed to "imitate the plant."

During this period in this country, several soil andcrop scientists advocated different procedures for"rapid tests for estimating fertility needs of soils." Theagricultural experiment station of each state seemed tohave a soil test that was different and better than that ofevery other state. Among these, was a procedure byBray (1) in Illinois in 1929. Some of the other well-known procedures were those by Truog (11) at Wiscon-sin in 1930, Spurway (9) at Michigan in 1933, Thornton(10) at Purdue in 1934, Morgan (7) at Connecticut 19J5, and Miles (6) at Maryland and Mississippi in 1937.

The common denominator of these procedures andthe hypothesis unde.rlying them all was that the soil testshould imitate the plant and remove from the soil thesame nutrients as the crop. Studies by plant scientistshad indicated that plant roots excrete CO2 and organicacids. These were assumed to dissolve the minerals ofthe soil; the nutrients thus released were taken up by thecrop. As a result of this assumption, all the solutions

PROFILES 133

used as extractants in soil testing were weak organicacids, dilute solutions of strong acids, or buffers de-signed to maintain the extract in the range of aciditythat was believed to surround plant roots.

In 1937 Roger Bray (2) presented a paper before thesoil chemistry section of the Soil Science Society to callattention to the futility of expecting a chemical solutionto imitate a plant and remove from the soil in a fewminutes the nutrients that roots would remove in an en-tire growing season. He argued that soil scientistsshould learn about the chemical soil forms of differentplant nutrients and devise methods to separate andmeasure those different chemical fractions. It wouldthen be possible to learn which chemical fractions wereimportant in crop growth and to calibrate the amountsof different fractions against crop yields. He ridiculedthe idea of a universal extractant for all plant nutrients.Since the chemistry of each plant nutrient is unique, itfollows that different extracting solutions may be re-quired in soil tests for different nutrients. Soils ofmarkedly different properties might even require differ-ent extracting solutions for the same nutrient.

The idea that soil testing should be based on measure-ments of the appropriate soil forms of the essential ele-ments was timely. Clay minerals had been recognizedand were being studied. Methods and instruments forchemical analyses were being developed. Chemical frac-tionations of soil P, N, K, and other elements werebeing attempted. Cation exchange reactions were beingstudied extensively. It became an article of faith amongworkers in soil fertility and soil chemistry that researchshould be done to learn about the chemistry of eachnutrient element in the soil. Once that knowledge wasobtained, it was accepted that a satisfactory soil testcould be devised. Another factor in the rapid acceptanceof soil testing was the scarcity of fertilizers and the highdemand for crop production brought on by World WarII.

A procedure that became known as the "Bray P-I"soil test for P was developed shortly before World WarII (4). This procedure came out of years of laboratorywork with samples from many soil experiment fieldswhere long term experiments with phosphate fertilizerswere being conducted. A basic objective of the overalllaboratory research program was to learn about the"soil forms" of P.

The P-1 procedure became "established" by thepublication in 1956 of a study by a national Soil TestWork Group (12) that had sent 74 samples from variety of soils of the United States and Canada to 55participating state and commercial soil testing labora-tories. The summary of the study reported that amongthe P tests in use, the P-l was most highly correlatedwith crop response and was also the one least affectedby soil properties.

In one of the classic papers of soil science, Dr. Braypublished in 1948 the article, "Requirements for a Suc-cessful Soil Test" (3), which summarized the concept "measuring the soil form." He listed three majorgeneral requirements: 1) The extracting solution should

remove as quantitatively as practical the soil form(s) the nutrient important to plant growth; 2) the amountremoved should be measured with reasonable accuracyand speed; and 3) there must be a useable relation be-tween the amounts extracted and the growth and re-sponse of the crop to the nutrient in fertilizer rate trialsunder various conditions.

To express the relation between soil test value andyield, Dr. Bray modified the Mitscherlich equation toinclude the soil test value of a nutrient as one term andthe amount of that nutrient added a fertilizer as anotherterm. As a result of Dr. Bray’s work, the "Mitscherlich-Baule percent yield concept" came to be used very wide-ly in this country.

Soil testing procedures developed during that periodand based on "measuring the soil forms" are still theones most widely used in soil testing laboratories. TheBray P-1 and Olson (8) bicarbonate methods for P areexamples. Exchangeable K, also the subject of much ofDr. Bray’s research, is the soil form of that elementalmost universally measured in soil testing procedures.The extensive use and longevity of such methods mustbe at least partly due to the general guidelines providedby the "Bray hypothesis" for the research behind soiltesting.

The hypothesis of "measuring the soil form" has bythis time been partially replaced in theory if not in prac-tice. Numerous approaches using more recent andcomplete knowledge have been proposed. We should begrateful, however, to Roger Bray for enunciating an ap-proach that provided for a great amount of progress inapplied agronomy.

Roger H. Bray was born 13 Oct. 1898 at Vineland,NJ. He received his B.S. degree in agricultural chemis-try from Pennsylvania State College in 1923. He cameto the University of Illinois as a graduate student inchemistry and obtained his M.S. under Roger Adams, alegendary figure in the field of organic chemistry. Dur-ing that period, Bray worked as student chemist in theAgronomy Department, and that experience stimulatedother interests. He transferred to Agronomy where hereceived his Ph.D. (with a minor in geology) under E. DeTurk.

In addition to his work with soil tests and the adapta-tion of the Mitscherlich-Baule yield equations for theinterpretation of soil tests, Roger Bray had many otherimpressive contributions as a scientist. He was authorand coauthor in a series of classic papers on loess in thedevelopment of Illinois soils and on the Illinois soilmaturity series. He was a member of the research teamwith Dr. R. E. Grim and Dr. W. F. Bradley that estab-lished the identification, composition, and structure ofthe group of clay minerals known as "illites" that occurwidely in Illinois and Corn-Belt soils. He developed theN-P-K plant tissue test kit and worked with the IllinoisDepartment of Public Health when a link between"blue baby disease" and nitrates in the water of farmwells was proposed.

Dr. Bray was active in the American Soil SurveyAssociation that predated the Soil Science Society of


America in which he served at different times as chair-man of both the soil chemistry and soil fertility sections(5).

Dr. Bray was also involved in community activitiesand took very seriously his responsibilities as a citizen.He was an accomplished violinist and a long time mem-ber of the Community United Church and its choir. Hewas active in Cub and Boy Scout work and the UrbanaExchange Club. He was emeritus professor by the timehe passed away 10 Sept. 1972.

NEWSFEATURES This new section of the Journal of Agronomic Education presents practices or ideas of interest to

readers. The items differ from regular articles in that they are of limited scope and cover events too recent for full documentation. The editor approves newsfeatures, and the editorial board solicits readers’ comments on the section. Send suggestions for newsfeatures to the Editor.

The first article in “Newsfeatures,” written by Editor W. A. Anderson, describes a group that finds, diagnoses, and controls crop problems in Minnesota. The group’s leader believes that other such groups could be formed to cope with changing crop problems elsewhere. Anderson, who teaches at the University of Minnesota Technical College, Waseca, found that belonging to the group helped him to prepare course material relevant to area problems. The second article announces the new Manual.

-D. A. Fuccillo Senior Managing Editor

S ltaying ahead of the problem

Operating from hindsight seemed inefficient to Dennis Rossell, an agriculture teacher in Minnesota. He used to lament after-the-fact discussions of field problems. Dis- covering, diagnosing, and control- ling field problems, such as pest in- festations, should have occurred before problems became severe, in Rossell’s opinion. He decided to do something about it.

A group was developed to antici- pate field problems. As a beginning, Rossell invited five agriculture teachers to take turns arranging visits to area farms. They met weekly to discuss current problems and visit farms where the problems could be spotted. Since 1982, the group has grown to include the county extension director, the exe- cutive director of the Agricultural Stabilization and Conservation Service, the district conservationist for the SCS, the county agricultural inspector, a crop consultant, a farmer, an agriculture teacher from a neighboring county, and a teaching agronomist from the University of Minnesota Technical College,

Waldorf-Pemberton High School. “The group has expertise in nearly all areas. We do not always agree, but we do discuss alternatives, hear different ideas, use our colleagues as a sounding board, and eventually make recommendations. The farmers who host our visits obtain good advice, and they feel that they are contributing to our education.”

The visits are beneficial for all involved. The farmer benefits by expert advice on crop production.

The group gains advanced warning on problems that may appear in other farmers’ fields. They also may collect materials to use with their clientele. Some photograph plants, weeds or damage symptoms for classroom use or for extension presentations. The county extension director uses the meetings and trips to prepare a weekly newspaper column and radio programs.

Examples of problems discussed are diverse: severe soil erosion on

Fig. 1. Rossell, right, and other professional ag group members, examine injury due to herbicide carryover in a farmer’s field. Group members make on-site inspections of fields where such problems exist.

Waseca (Fig. 1). “We have become a problem-

solving group,” says this teacher at 135


rented farmland, herbicide damageto crops, misapplication of ferti-lizer, leaf chlorosis, hail damage,crop diseases, insects, weeds, andgrain storage problems.

According to Mark Blauert, acounty extension agent, the recom-mendations of the group have a greatimpact. "Farmers in the area oftenask for more than one professionalopinion," he said. "If the farmer

receives different messages, he maycome to the conclusion that the ’ex-perts’ don’t know what they aretalking about. Discrepancies onavailable information do exist, andthose of us most often asked for ad-vice should come to agreement onrecommendations to avoid con-fusion. ’ ’

Rossell summed it up this way."Our crops are constantly

changing. They grow rapidly andencounter different problemsthroughout the growing season. Theformation of this group certainlyfilled a need, and the idea couldeasily be duplicated in other coun-ties."

W. A. AndersonUniv. of Minnesota

Waseca

New PublicationsManual updates

SI units useA new Pubfications Handbook

and Style Manual replaces an earlierversion distributed by the associatedsocieties in 1976. This handbook de-scribes procedures and gives instruc-tions on how to prepare and submitmanuscripts for publication by theAmerican Society of Agronomy,Crop Science Society of America,and Soil Science Society of Ameri-

New and expanded sectionsinclude use of SI (Syst6me Interna-tional d’Unit6s) because the socie-ties require the units in their publi-cations. Certain SI units are fre-quently used in the agronomic,crop, and soil sciences. The socie-ties’ journals publish tables of suchunits, along with conversion factorsfor other units (Tables 1 and 2).

Professionals and students in theagronomic and related disciplinesneed confidence in the use of theseunits, and the Manual should easethe transition.

The Manual is available withoutcharge to members of the societies.For nonmembers the charge is $3.00prepaid in the USA, $3.75 outsidethe USA. If not prepaid, add $2.00for invoicing and handling. Addressrequests to ASA HeadquartersOffice, 677 South Segoe Road,Madison, WI 53711 USA.

Table 1. Examples of preferred (P) and alternate (A) unitsfor general use.

Quantity Application Unit Symbol

Area Land area

Leaf areaSpecific surface

area of soilDensity Soil bulk densityElectrical Salt tolerance

conductivitytElongation rate Plant

Ethylene N2 - rLxing activityproduction

Extractable ions SoilFertilizer rates Soil

Fiber strength Cotton fibers

Flux density Heat flowGas diffusion

Water flow

Gasdiffusivity Gas diffusionGrain test Grain

weightHydraulic Water flow

conductivity

Ion transport Ion uptake

Leaf area ratio PlantLength Soil depthMagnetic flux Electronic spin

density resonance (ESR)Nutrient Plant

concentrationPhotosynthetic CO~ amount of sub-

density (P)CO, mass flux

density (A)Plant growth

rateResistance StomatalSoil texture Soil

composition

square meter (P) m2

hectare (A) hasquare meter msquare meter per kilogram m~ kg-~

megagram per cubic meter Mg m-J

decisiemens per meter dS m"

millimeter per second (P) mm s-~

millimeter per day (A) mm day-’nanomole per plant nmol plant-~ s-~

secondmilligram per kilogram mg kg-~

grams per square meter (P) g m-2

kilogram per hectare (A) kg ha-~

kilonewton meter per kN m kg-’kilogram

watts per square meter W rn-~mole per square meter mol m-~ s-’

second (P)gram per square meter g m

second (A)kilogram per square kg m-2 s-~

meter second (P)cubic meter per square me m"2 s-~ or

meter second (A) m s-’square meter per second m~ s"~

kilogram per cubic meter kg m-~

kilogram second per kg s m-s

cubic meter (P)cubic meter second me s kg-’

per kilogram (A)meter per second (A) mmole per kilogram (of dry tool kg-~ s"~

plant tissue) secondmole of charge per kilo- tool ( + ) kg-’ -~

gram (of dry plant ortissue) second mol (-) "~ s-’

square meter per kilogram m~ kg"~

meter mtesla T

millimole per kilogram (P) mmol kg"~

gram per kilogram (A) g kg-’micromole per square smol m-~ s-~

meter second (P)

milligram per square mg m"~ s-’meter second

gram per square meter g m-2 day"~

daysecond per meter s m"~

gram per kilogram (P) g kg-’percent (A)

(continued on next page)

NEWSFEATURES 137

Table 1. Continued.

joule per kilogram Kelvin J kg’’ K-’watt per meter Kelvin W m"~ K"

Specific heat Heat storageThermal Heat flow

conductivityTranspiration H20 flux density gram per square meter g m-2 s-~

rate second (P)cubic meter per square m~ m-2 s"~ or

meter second (A) m s"~

Volume Field or cubic meter (P) m’Laboratory liter (A) L

Water content Plant gram water per kilogram g kg"wet or dry tissue

Soil kilogram water per kilo- kg kg"gram dry soil (P)

cubic meter water per m’ m-~

cubic meter soil (A)X-ray diffrac- Soil radians (P) 0

tion patterns degrees (A) o

Yield Grain or forage yield gram per square meter (P) g m-2

kilogram per hectare (A) kg ha"megagram per hectare (A) Mg ha-’tonne per hectare (A) t ha"

Mass of plant or gram (gram per plant g (g plant-’ orplant part or plant part) g kernel-’)

The term, "electrolytic conductivity", has been substituted for "electrical conduc-tivity" by the International Union of Pure and Applied Chemistry (IUPAC). Useof the SI term, "electrolytic conductivity" is permissible but not mandatory inASA publications at this time.

Table 2. Factors for converting non-Sl units to acceptable units.

Noo-Si Units Acceptable Units

Multiply By To obtain

acre 4.05 x 10~ square meter, me

acre 0.405 hectare, ha (10’ 2)

acre 4.05 x 10" square kilometer, kmZ (10" Z)

Angstrom unit 0. I nanometer, nm (10-’ m)atmosphere 0.101 ~ megapascal, MPa (10" Pa)bar 0. I megapascai, MPa (10’ Pa)British thermal unit 1.05 x 10~ joule, Jcalorie 4.19 joule, Jcalorie I~r square centi-

meter minute (irradianc¢) 698 watt per square meter, W m-2

calorie per squarecentimeter (langley) 4.19 x 10" joules per square meter, J m"~

cubic feet 0.028 cubic meter, m~

cubic feet 28.3 liter, L (10"~ m~)

cubic inch 1.64 x 10"s cubic meter, m~

(continued)

Table 2. Continued.

curie 3.7 x 10’0degrees (angle) 1.75 x 10dyne 10"s

erg 10-’foot 0.305foot-pound 1.36gallon 3.78gallon per acre 9.35gauss 10-’gram per cubic centimeter 1.00gram per squa.re decimeter 27.8

hour (transpiration)inch 25.4micromole (H~O) per square 180

centimeter second(transpiration)

micron 1.00mile 1.61mile per hour 0.477milligram per square 0.0278

decimeter hour(apparent photosynthesis)

milligram per square 10 000centimeter second(transpiration)

millimho per centimeter 0. Iounce 28.4ounce (fluid) 2.96 x 10pint (liquid) 0.473pound 454pound per acre 1.12pound per acre 1.12 x 10pound per bushel 12.87pound per cubic foot 16.02pound per cubic inch 2.77 xpound per square foot 47.9pound per square inch 6.90 x 10quart (liquid) 0.946quintal (metric)tad 1.00roentgen 1.00square centimeter per gram 0.1square feet 9.29 x 10square inch 645square mile 2.59square millimeter per gram 10"~

temperature (°F - 32) 0.556temperature (°C + 273) 1tonne (metric) 10;ton (2000 lb) 907ton (2000 Ib) per acre 2.24

becquerel, Bqradian, radnewton, Njoule, Jmeter, mjoule, Jliter, L (10-’ ~)

liter per hectare, L ha"tesla, Tmegagram per cubic meter, Mgmilligram per square meter

second, mg m"~ s" (10"~ g m-2 s"~)

millimeter, mm (10"~ m)milligram (H~O) per square meter

second, mg m-2 s"~ (10-~ g m-~ s"~)

micrometer, ~m (10-~ m)kilometer, km (10~ m)meter per se.cond, mmilligram per square meter

second, mg m-2 s"~ (10"~ g m

milligram per square metersecond, mg m"2 s-’ (10-~ g m"~ s-’)

siemen per meter, S m-’gram, g (10"~ kg)liter, L (10"~ m~)

liter, L (10"~ m~)

gram, g (10"~ kg)kilogram per hectare, kg ha’’

megagram per hectare, Mg ha-’kilogram per cubic meter, kg m-~

kilogram per cubic meter, kgkilogram per cubic meter, kgpascal, Papascal, Paliter, L (10"~

kilogram, kg0.01 Gy2.58 × 10" C (coulomb) ’’

square meter per kilogram, m~ kg-’square meter, m~

square millimeter, mm~ (I -~ msquare kilometer, km~

square meter per kilogram, m~ kg-t

temperature, °Ctemperature, Kkilogram, kgkilogram, kgmegagram per hectare, Mg ha-’

SELECTIONS FROM THE BOOKSHELF

No-Tillage Agriculture: Principles andPractices--RonaM E. Phillips andShirley H. Phillips (ed.). VanNostrand Reinhold, United Kingdom.1984. 320 p. 60 illustrations. Cloth$34.50.

The editors author or coauthor sevenof the 12 chapters in the book. The otherauthors are colleagues of the editors atthe University of Kentucky. Their ex-pertise range from weed science to soilchemistry and microbiology. All arehighly qualified to write their respectivechapters.

Each chapter title will be followed bya description of the content and will givecomments by the reviewer.

Chapter 1, Introduction. This chapterlists reasons for tillage with associatedadvantages and disadvantages of tillagevs. no-tillage. A brief history of no-till-age development is given. It was disturb-ing not to find the names of no-tillagepioneers that have worked in the semi-arid portions of the USA. The authorhas been very provincial in historical de-velopment but does have a broad per-spective in terms of other subjects dis-cussed. This entire chapter is quiteverbose in some respects.

Chapter 2, Effects of Climate on Per-formance of No-Tillage. A very compre-hensive treatment of the relationships ofno-tillage to precipitation-evaporationratios, soil temperature, corn seedlinggrowth as related to soil temperature,and time of planting is covered in thischapter. It is well documented and is in-novative in respect to predicting whatclimates might be adapted to no-tillage.In places it is tedious to read. The authorcould have used fewer details at somepoints and still communicated clearly. Itis above the level of most farmers and re-quires some science background on thepart of the reader.

Chapter 3, Soil Adaptability for No-Tillage. It includes a well organized and

complete description of no-tillage inrelation to soil drainage, topography,and soil erosion by wind and water. It isweakest in the wind erosion section hutstill adequate. It is easy to read and thedata illustrations chosen are excellent.

Chapter 4, Soil Moisture. The authorhas done an outstanding job of explain-ing the principles of mulch effects onsoil water evaporation. He also coversthe relationships of soil texture, pans,and drainage with respect to no-tillageand soil water conservation. Thischapter, like the previous ones, is weakin respect to information for the semi-arid nonirrigated areas of the world. Theroot growth section of the chapter is itsweakest part and could have been mini-mized with no loss to the reader.

Chapter 5, Fertilization and Liming.The authors provide an excellent discus-sion of appropriately chosen data tosupport their presentation of fertiliza-tion principles under no-tillage condi-tions. It is by far the best written chapterin the book. Proper application tech-niques for N fertilizer are emphasizedand data to support the recommenda-tions are presented. Placement of othernutrients is also discussed. The chapterconcludes with a strong section on therole of cover crops in N fertilization ofno-tillage soils. Even though the in-formation was presented in great detailthe authors kept it very "readable." Thereference section is very complete.

Chapter 6, Energy Requirement inNo-Tillage. A concisely writtenthorough treatment of the energy use re-quirements of no-tillage vs. convention-al systems is covered in this chapter. Itprovides energy use data for all aspectsof the systems from equipment manu-facture to herbicide manufacture toapplication of materials, all in units of"diesel fuel equivalent."

Chapter 7, Response of Weeds andHerbicides Under No-Tillage Condi-tions. This chapter provides a barely

adequate treatment of the subject andlacks the orientation toward principlesfound in other chapters of the book.This makes it boring to read and lessvaluable compared to other chapters. Italso overlooks herbicide use in drier cli-matic regions. Overall it is a disappoint-ingly weak point in a book that covers asubject area so highly dependent onproper herbicide use.

Chapter 8, Other Pests in No-Tillageand Their Control. This is a "catch all"chapter that covers the pertinent diseaseand insect problems. It contains moredeta, il than is necessary in some places.

Chapter 9, Changes in Soil PropertiesUnder No-Tillage. This is an importantchapter but not as concisely written asone would have hoped. From pages 215-225 it repeats much of what is in Chapter5. All aspects of the microbial, physical,and chemical environments of the soilare covered.

Chapter 10, Multicropping. Theauthors open the chapter by stating that"multicropping may be the most im-portant factor in no-tillage agriculture."This is a very provincial view that ig-nores the large cultivated areas of theworld that are either too dry or too coldto support multicropping. This chapterdoes a thorough job of covering multi-cropping in areas where it is applicable,but is verbose.

Chapter 11, Equipment. This chaptergives an adequate description of equip-ment and is probably as specific as onecan be in this area.

Chapter 12, Tropics. This chapter hasan interesting, comprehensive, eye open-ing discussion of the potential for no-tillage farming in the tropics. The discus-sion o’f the effects of no-tillage systemson human resources is especially good.Its weakness is the verbosity of the last10 pages.

Overall this book is a good summa-tion of our knowledge in no-tillage agri-culture. It has depth and is "principle

138

SELECTIONS FROM THE BOOKSELF 139

oriented" in most chapters. Althoughadvertised as a guide for farmers, it isprobably beyond their comprehensionunless they have had a class in soil sci-ence. It would fit any soil or crop man-agement class that has an introductorysoil science prerequisite. Since the bookis on a specific topic, no-tillage agri-culture, it would probably be used bestas a secondary or supplementary text inmanagement courses. Unfortunately it isavailable only in "cloth" and would bean expensive book to use in this role.

--Gary A. PetersonDepartment of AgronomyColorado State University

Fort Collins

Weed-Crop Ecology, Principles in WeedManagement--R. J. Aldrich. BretonPublishers, North Scituate, MA.1984. 465 p. Illus.

(Two individuals wrote reviews of thisbook independently. Both reviews areprinted here because, although the re-views reinforce each other, the reviewersoffer their own insights into using thebook for teaching.)

R. J. Aldrich wrote this text to fill thegap between weed control and weedbiology/demography. He has admirablysucceeded with a book that should bemandatory reading for those of us cur-rently involved in teaching weed man-agement courses.

The author grasps the readers’ atten-tion in the introductory chapter by con-vincingly redefining "weed", not as wedutifully teach our students "a plant ou~of place", but as a "plant that origi:nated under a natural environment and,in response to imposed and natural en-vironments, evolved, and continues todo so, as an interfering associate with ourcrops and activities." This definitionmay be somewhat more cumbersome forstudents and instructors, but is difficultto argue with after reading the author’sjustifications.

The author proposes a new mind-settoward weeds, noting that for the mostpart, current weed control practices dealwith specific weeds in given crops in asingle year. This year-to-year approachhas allowed for the emergence of newproblem weeds, which are dealt withwhen the seriousness of their encroach-ment is finally realized. The authorrecommends a long-term approach,focusing on weed prevention, seedbank

reduction, and a lessening of competitionfrom weeds that remain present, usingall that is known about "competition,about the weeds themselves, allelopathy,biological agents, and, of course, herbi-cides."

I found the text very informative, andimplemented many of the concepts intomy Weed Control course that was weakfor lack of good teaching ideas. Many ofthe questions I had concerning weedswere answered in the text. The section invarious chapters, entitled the "Weed’sEye View," was a fascinating and effec-tive way to explain concepts concerningweed seed germination, growth,survival, control, and competition withcrops and other weeds.

The book is comprised of 15 chapters,a glossary, index, and appendix tables.Detailed discussions are found concern-ing reproduction of weeds, dissemina-tion, development and reduction of theseedbank, seed longevity, dormancy,and competitiveness of weeds. Fourchapters focus on herbicide use, entry,effects, selectivity, persistence in soil,and factors affecting success. Eachchapter concludes with a summary sec-tion of concepts and conclusions, fol-lowed by an extensive reference list.

Topics not within the scope of the textand adequately covered elsewhere are re-ferred to, rather than rewritten in thisbook. I appreciate the author’s willing-ness to reduce the text length and givecredit and reference to other authorswhose works are current and note-worthy.

Control techniques discussed in thebook include allelopathy, biotic agents,herbicides, and various crop productionpractices. A final chapter entitled "ATotal Weed Management Approach"attempts to illustrate the author’s long-term approach to weed management.Some of the total management ap-proaches may seem somewhat idealistic,and may not receive total support fromthe farmer or the soils colleague. Theauthor does refer to this approach as"our program for the future"; thus heundoubtedly understands the limita-tions. I’m not sure at this time manyfarmers have access to information con-cerning varieties known to be allelopath-ic towards weed species, or that com-paction and erosion resulting from sug-gested practices will be viewed favorablyby the local soil conservationist.

There were a few disappointments inthe book. Some weeds were not identi-fied according to common standardizedterminology as suggested by the Termin-ology Committee of the Weed Science

Society of America. Some figures weredifficult to interpret, and some photoslacked clarity. For the most part, how-ever, illustrations, photographs, andfigures were good.

The book is aimed at college studentsenrolled in introductory courses in weedscience or weed-crop ecology. Practical-ly it would be appreciated and under-stood best in upper level undergraduateor graduate courses. My major concernin using this text in an introductorycourse would be the length of the text,the detail, and some of the terminologythat might be of interest to graduate stu-dents and faculty, but of little use to lessexperienced students working towardAAS or BS degrees. I highly recommendthe text as a resource for faculty in-volved in teaching weed management.

William A. AndersonAg Industries and Production Division

University of MinnesotaTechnical College

Waseca

Aldrich has provided a unique, time-ly, and much needed weed science text-book. Weed science texts in the pasthave dealt either primarily with weedbiology/ecology, or with methods ofweed control; comprehensive explana-tions of weed-crop relationships are few.This book explores weed-crop interac-tions in sufficient depth to give the stu-dent a perspective of the relationship be-tween weed-crop ecology and weedcontrol. As Aldrich suggests in his intro-ductory chapter, prediction of futureweed problems and preventive means ofcontrol are largely goals at present; theadvancement of those goals can begained only by a greater understandingof the ecological relationships that existin the weed-crop community.

Aldrich’s definition of a weed epito-mizes the approach that he has chosenfor this text. Instead of defining weedssimply as plants growing where they arenot wanted, they are defined as "plantsthat originated under a natural environ-ment and, in response to imposed andnatural environments, evolved, andcontinue to do so, as an interfering as-sociate with our crops and activities."Volunteer crop plants are defined simplyas that--volunteer corn, wheat, or someother crop.

Chapter 2 explores the ecological con-cepts needed to understand why weedsexist, and why they occur where they do.Chapters 3 through 5 examine weed re-production from seed and vegetative


organs, and the resumption of growth,including the important aspect ofdormancy.

Chapters 6 through 9 encompassaspects of weed interference, both directcompetition and allelopathy. Thefactors affecting crop yield loss as a re-sult of weed interference are examinedquantitatively. The influence of weeddensity and weed weight on crop yieldare presented, as are the effects of theduration of weed interference in crops,and the requirement for an early weed-free period to prevent yield loss. Theinterrelationships of allelopathy in weedinterference are postulat.ed, and theproblems inherent in its study clearly de-fined.

Chapters 9 through 14 of this text re-view methods of weed control. Chapter9 concerns the role of biotic agents in thesuccessful control of weeds. Chapters 10through 13 deal with various aspects ofherbicide use, and Chapter 14 examinesthe influence of cultural practices onweed control.

Perhaps the weakest part of this text isthe summarizing chapter. Manyreferences to this summary are made inthe preceding chapters, but it falls shortin providing real answers to a total weedmanagement approach, as suggested bythe chapter title. Had its advance billingnot been so great, perhaps the chapterwould have provided what it intended; arealistic evaluation of the potential valueof weed-crop ecology for the weed scien-tist. In general, however, the flaws inAldrich’s book seem minor, and thebroad perspective taken by the authormake it a valuable introductory weedscience textbook.

Beth SwisherAssistant Professor

Agronomy DepartmentUniversity of Nebraska

Lincoln

Genetic Engineering of Plants: Agricul-tural Research Opportunities andPolicy Concerns--Leslie Roberts. Na-tional Academy Press, Washington,DC. 1984. 96 p. Illustrated. Paper.$9.50.

This well-written book is a concise re-port (76 pages of text) of a convocationcosponsored by the Board on Agricul-ture of the National Research Counciland the Council for Research Planningin Biological Sciences, and held 23-24May 1983, at the National Academy ofSciences. The list of 33 convocation

participants includes well known scien-tists and science policy makers fromgovernment, industry, and universities.Several of the participants are from de-partments of agronomy and other bio-logical sciences.

Following a brief introductorychapter, the book has chapters bearingthe following titles: Crop Improvement,Gene Transfer, A Tool for FundamentalPlant Science, Somatic Cell Genetics,Applying the Tools of Biotechnology toAgricultural Problems, Policy and In-stitutional Considerations, University-Industry Relations, Safety Regulations,and Patents. These titles accurately re-flect the rather wide diversity of topicsconsidered in the book.

A statement in the preface indicatesthat the book "is intended to serve as anintroduction and guide for those whowish to follow the development of thispromising new technology." Consistentwith this purpose, the presentationsdealing with technical aspects of geneticengineering are not highly detailed.These presentations will probably bemost interesting and useful to scientistsin fields other than genetic engineering,and to nonscientists. They are not in-tended to serve as laboratory instruc-tions for researchers actively working ingenetic engineering.

The chapters dealing with policymatters raise a number of importantissues such as support for plant research,the possibility for conflict of interestwhen university employees participateactively in commercial enterprises,patent rights, public safety, etc. As onemight expect, no magic formula foravoiding the problems associated withthese issues is offered.

Leslie Roberts is a science writer, who,in my opinion, has done an excellent jobof writing in summarizing this interest-ing and important convocation. Thereport is well balanced--the greatpotential of genetic engineering is clearlypresented, but the point is also madethat in the near term, the main benefitmay be increased knowledge of howplants work rather than increased pro-duction or profits for the farmer. Iwould recommend the book as supple-mental reading for a number ofagronomy courses, not only those deal-ing with genetics and plant breeding, butalso crop production courses.

I noticed the following two errors inthe text: (1) On p. 24, the genome of thepotato spindle tuber viroid is said toconsist of "359 nucleotide base pairs."Actually, the single-stranded RNA ofthis viroid includes 359 nucleotides, notpairs. (2) On p. 57 a statement is made

the effect that the private (italics mine)sector is responsible for advancing basicknowledge and training future scientists.This statement is at variance with thesense of the context in which it appears,and with prevailing views concerning theresponsibility of public institutions.

--F. A. HaskinsAgronomy DepartmentUniversity of Nebraska

Lincoln

Introductory Plant Physiology--G. RayNoggle and George J. Fritz. Prentice-Hall, Inc., Englewood Cliffs, NJ.Second Ed. 1983. 627 p. Hardcover.

This second edition is an updated, ex-cellent, and quite detailed treatise on thephysiological processes of plants. Itbrings to researchers, teachers, andgraduate and undergraduate students awealth of information on the functionalaspects of higher plants. The book con-sists of 18 chapters covering subjectswhich are quite diverse, and yet each isrelated to the other, with a wealth ofreference materials. Each chapterpresents the most recent research find-ings, with significant sections devoted todiscussion of water/plant relationships,and the uses of plant growth substancesin agriculture.

Some of the specific physiological andbiochemical aspects discussed includestomatal movement, antitranspirants,water stress and its physiological conse-quences, allelochemics and mechanismsof action of plant growth substances,.and photorespiration. The book hasother strong points, including a po-tentially very useful list of references atthe end of each chapter.

We are delighted with the harmony ofpresentations, photograph quality, andclarity of expressions. The authors havedone an excellent job of presenting up-to-date information in a brief and highlysequential form.

In general, we found the book to bevery readable, well illustrated, compre-hensive, and logically organized. It is anexcellent reference for all those inter-ested in the challenges of plant physiolo-gY.

--Fouad M. BasiounyJames R. Allen

ProfessorsDepartment of Agricultural Sciences

Tuskegee InstituteAlabama

SELECTIONS FROM THE BOOKSHELF 141

Vegetables in the Tropics--/-/. D.Tindall. AVI Publishing Company,Inc., Westport, CT. 1983. 533 p., 81illustrations.

The author describes this work as ahandbook to provide information onvegetable crops grown in the tropics,which can be applied in practice. Thebook is targeted to students, vegetablegrowers, extension officers, researchworkers, and administrators who seek toincrease production of vegetable crops.Although no single volume could ade-quately cover vegetable productionunder the great diversity of climates,land, and culture in the tropics, theauthor has provided a very useful,handy and easily read guide for thepractical grower.

The introductory section deals withthe effects of physical environmentalfactors, cultural practices, tools, propa-gation methods, weed control,agricultural chemicals, irrigation, pestsand diseases, harvesting and storage,vegetable production and the use, andnutritional composition of vegetables,including a select reference list. Thebrevity of the introduction (13 pages)allows only a cursory discussion of eachtopic, but a useful orientation to thesubject matter. The main portion of thework describes vegetables commonlygrown and used in the tropics. They arepresented in alphabetical order byfamily, genus, and species. Select refer-ences follow the description of eachfamily. Two appendices are provided:vegetable cultivars grown in tropicalareas, and crop protection details. Asupplemental bibliography is alsoincluded in the volume.

The format used in describing eachvegetable includes common name, centerof origin and distribution, areas of culti-vation, botanical description, environ-mental responses, cultural requirements,growth period and harvesting, prepara-tion for market and storage, use and nu-tritional composition, and pest diseasescommon to the vegetable. The nutrition-al values and description and control ofpests and disease are tabulated for eachfamily and treated in greater detail in theAppendix. The line drawings of selectvegetables are clear and helpful, but thepoor quality of the photography fails toenhance the description. The volume is avaluable asset to agriculturalists,especially extension workers serving intropical countries. It provides a basicsource of ready information which canbe augmented by regional publicationswhich give detailed information for acrop in a specific geographical area. The

book is not directed to any particularlevel of field operation. Modificationscan be made for very large or smallenterprises. The author has providedsufficient practical data for a profession-al horticulturist or for an extensionagent assisting a grass roots farmer toraise a crop using techniques applicableto the local climate, soils, and scale ofcultural operations.

Eugene BramsCollege of Agriculture

Prairie View A&M University(Texas A&M University System)

Prairie View, TX

Agricultural Computer Programming,A Practical Guide--Richard A.Levins and W. Charles Walden.Prentice-Hall, Inc., Englewood Cliffs,NJ. 1983. 147 p. 10 photograph illus-trations, 5 flowcharts of programs.Paper. $10.95.

This is an extremely useful book foranyone who is getting acquainted with acomputer. It is very clearly written inlanguage suitable for general audiences.It describes the workings of microcom-puters in simple terms, and describessteps necessary in programming a com-puter. The reader is led through devel-opment of 13 programs that apply tovarious aspects of an agricultural opera-tion. Assuming that one who reads thisbook either has or will soon have accessto a microcomputer to use in operationalplanning, I could not think of a moreuseful reference for that individual tohave on hand.

The first four chapters discuss somebasics about the microcomputer, com-puter concepts, and describe hardware.In Chapter 4 the "breakeven price" pro-gram is used to introduce the proceduresof programming. This is a very simpleprogram, but it nicely illustrates thesteps necessary in getting a computer towork for the user. Chapter 5 followswith a discussion of why each of the pro-gramming tasks was accomplished. Aseries of programs are presented inChapters 6 through 17, beginning withprograms that are relatively short. Thereare two programs to check tractor speed,a machine capacity program, one onbreakeven price for livestock, and a loanpayment program. In addition there areprograms that allow the user to evaluatecustom work vs. machinery ownership,the most efficient number of rows peracre, and crops which provide the bestreturn. There is a program to help judge

the most efficient size of cultivatedfields, to calculate costs of farm grainstorage, and to plan for loan ammortiza-tion. The last program presentedformulates a livestock ration. Theseprograms are written in BASIC languageand are presented stepwise in a mannerthat is easy to follow, even for one whohas only a casual acquaintance with acomputer. The last 3 chapters of thebook deal with using printers, the easeof reading programs, and things toconsider when buying a computer pro-gram. The final chapter summarizessome more advanced computerlanguages.

The authors of this book stress thatdevelopment of a "plain-English" pro-gram prior to attempting to write a com-puter program is an essential part of theprocess. Each computer programpresented is preceded by such a pro-gram. To quote the authors, "--a com-puter program cannot be written unlessa plain-English program that details thejob in a step-by-step fashion can be writ-ten first. In the same way, you cannotadequately judge a program that doessomething you don’t understand." Themoral as pointed out at the end ofChapter 21, is to know what you wantfrom a program before you set out towrite one, or to buy one from somesource.

I found nothing in this book I wouldchange. I learned a great deal from re-viewing it even though I have nocomputer to program. The basics ofBASIC are in the book. Reading itwould be one of the most useful thingsthe owner of a new computer could do.

--David T. LewisDepartment of Agronomy

University of NebraskaLincoln

The Nature and Properties of Soils--Ninth Edition--N. C. Brady. Mac-millan Publishing Co., New York.1984. 750 p.

This book is a revised edition of a longseries of soil science texts (since 1922) one or more of the authors Lyon, Buck-man, and Brady. It embodies the samehigh quality that characterized the previ-ous editions. The content of the bookhas been changed only slightly, but theorder of the chapters has been signifi-cantly altered. The resulting sequence ofpresentation of topics is an improvementover that in the eighth edition.

After an introductory chapter, the


next seven chapters cover conventionaltopics in basic soil science including soilphysical, chemical, and biologicalproperties. Unfortunately, one of themost basic part of soils, genesis, andclassification, is placed much later in thebook (Chapters 12-14). Three chapters(Chapters 9-11) describe the soil nutri-ents. Topics in soil management are dis-cussed in Chapters 14-18. The finalthree chapters describe recycling organicwastes, soil pollution, and the relation-ship between soil science and the worldfood supply.

The information in the book is ac-curate, recently updated, and complete.Obsolete classification schemes havebeen almost totally replaced by modernschemes except for a minor lapse inChapter 6. Older names are defined inthe glossary for those who are inter-ested; however, these names are not re-lated to newer names.

Excellent illustrations and datapresentations are provided throughoutthe book. An appropriate number ofreferences are listed at the end of eachchapter. A comprehensive glossary ispresented at the end of the book. Thebook is generally well written and theformat is attractive. The book is some-what larger in dimensions and numberof pages than the eighth edition as a re-sult of more illustrations, slightly largerprint, wider margins, and some addi-tional information. One chapter fromthe eighth edition on supply and avail-ability of plant nutrients has beenomitted; however that material isadequately covered in other chapters.For most quantities SI metric units havebeen introduced in a way that most stu-dents should be able to understand.

Despite the overall excellence of thebook, it may have deficiencies forspecific applications. First, theinformation is strongly oriented towardsoils as used for agricultural production.Resource aspects of soils receive less em-phasis. This is evident in little or nocoverage on land-use planning, engi-neering properties of soils, and horti-cultural soil applications. Although acomprehensive discussion of these topicsis not within the scope of this book,familiarity with these topics may be im-portant in some soil science courses.

Second, although the author expressesa wish that the book will be useful forstudents of tropical soils, the orientationof the book is mainly toward humid-region United States agriculture.Limited information is available on soilsof arid regions or soils of the tropics.This information is found in parts oftwo chapters, Chapter 6 and 21, respec-tively.

Third, there are two areas in which theinformation in this book may not beconsistent with what students learn inother science courses. The classificationof organisms departs from what is beingtaught in many microbiology courses.Also, some chemical aspects of soilacidity and its correction are expressedin a rather archaic manner; thus this in-formation may be difficult for studentsto relate to their chemistry courses.

Fourth, in some applications, thescience and practice of soil testing, theinterpretations of plant analysis dataand fertilizer economics may need to begreatly augmented since coverage in thisbook is rather limited.

Fifth, the main strength of the bookmay also be a weakness for some uses.Whereas the comprehensive and scien-tific approach employed in the book iswell suited for classes where studentshave a strong background in basic sciencences and agriculture, beginningstudents with limited scientific prepara-tion, and little or no agricultural back-ground may need a more general and ex-perience-oriented approach to the studyof soil science. Further, only a limitedamount of the wealth of materialcovered in this book can be included in aone-semester freshman soils course.Therefore, students may feel exploitedby having to purchase the book if theyplan to take no more soil science.

For adequately prepared students withprimary interest in agricultural applica-tions of soil science, this book is well-suited and is probably among the bestavailable. It should also be a valuablereference for anyone who has a continu-ing need for a wide range of informationregarding the more basic aspects of soilscience.

--Robert C. SorensenDepartment of Agronomy


The Visual Display of Quantitative In-formation--Edward R. Tufte. Graph-ics Press, Cheshire, CT. 197 p. $34.00postpaid. Available only by orderingdirectly.

This book has excellent graphic de-sign, thanks largely to the author, hisown publisher. Edward Tufte is a pro-fessor of political science and statistics atYale University. He discusses the designof statistical displays for many fields,and claims the book describes how tocommunicate information through thesimultaneous presentation of words,

numbers, and pictures. According toTufte, each year, the world over, some-where between 900 billion and 2 trillionstatistical graphic images are printed. Hesays that the principles in this bookapply to most of them. Quite a chal-lenge!

Visual Display of Quantitative In-formation is at the same time broad anddiffuse, shows excellent material andcondemns all else, and proposes a theoryfrom "principles" consisting of jargonto explain it. Nevertheless, Tufteprovokes the reader to examine graph-ical design from a viewpoint of ex-cellence. He calls the book a celebrationof data graphics. And it is.

In the first of two parts, Tufte dazzlesthe reader with outstanding drawingswhile defining data graphics as visualdisplays of measured quantities bymeans of the combined use of points,lines, a coordinate system, numbers,symbols, words, shading, and color. Oc-casionally we lost Tufte’s trail, but thestunning graphic vistas compensated forbeing lost: detailed informative datamaps such as one on the age-adjusteddeath rate from various types of cancer;time-series, which he calls the most fre-quently used form of graphic design,such as the movement of a starfish turn-ing itself over; and narrative graphics ofspace and time, such as a classic drawingby a French engineer showing the dis-astrous fate of Napoleon’s army inRussia. From these examples, Tufte pro-claims five principles of graphical ex-cellence. He returns to these principleslater in the book. Meanwhile in the nexttwo chapters, on Graphic Integrity andSophistication, Tufte shows how statis-tics can be used to tell lies. The first partends with a plea to remedy "graphicmediocrity" and misleading "chartjunk" and a condemnation of illustra-tors. The elitist tone of this chapterprobably will inflame graphic designersas well as illustrators, who produce thebulk of the published material Tufteeschews as mediocre.

The second part of the book intro-duces a theory of data graphics. He usesthe terms data-ink, chart-junk, and datadensity to explain the concepts. Tufte’sprinciples of graphical excellence are:* Well-designed presentation of interest-

ing data.* Complex ideas communicated with

clarity, precision, and efficiency.* Presenting the greatest number of

ideas in the shortest time with the leastink in the smallest space.

* Multivariate information.* Telling the truth about the data.

Few persons would argue with theprinciples, especially since Tufte re-

SELECTIONS FROM THE BOOKSHELF 143

peatedly uses the words "within reason"to bridle enthusiastic reductionism ofthe theory derived from them. Un-fortunately, it seems to us, Tufte carriessome of the ideas to extremes, as in hisapplication of the rule of simplicity byerasing most parts of a graphic to sim-plify it. The device of using jargon todescribe application of these principlesalso seems out-of-place in the excellentdesign advice he is giving.

Tufte ends the book with a chapter onaesthetics and technique. This chapterpresents useful information to the scien-tific author, who must often choose be-tween using graphs or words. He showshow to make complex material accessi-ble to readers by combining words,numbers, and pictures. He hits adiscordant note again, however, inpresenting a fascimile of a Leonardo DaVinci manuscript that imbeds figures inthe text. Few modern writers and fewerstill publishers can produce such integra-tion of these elements. We would haveliked Tufte to advise us what to do now.In summary, this is an excellently pre-pared, provocative book to buy andadmire. Some parts will be useful to in-structors and others who preparegraphic material for publication. Itshould stimulate comment on design ofstatistical graphs and controlled researchefforts to subject some of Tufte’srecommendations to tests. Andprobably it will be controversial whilethe ideas Tufte presents are tried.

--Domenic A. FuccilloSenior Managing Editor

Journal of Agronomic EducationAmerican Society of Agronomy

Madison, WI

Richard PowersProfessor

Department of Agricultural JournalismUniversity of Wisconsin

Madison

World Vegetables--Principles, Produc-tion and Nutritive Values--MasYamaguchi. AVI Publishing Com-pany, Inc., Westport, CT. 1983.145 p.

The author compiled this volumefrom notes and syllabi developed during10 years of teaching World Vegetables inthe Department of Vegetable Crops,University of California, Davis. Thefirst section adequately treats l) vegeta-bles and world food supply, 2) originand evolution of vegetables, and 3) theimportance of vegetables in nutrition,

including toxic properties and folk medi-cine. This initial section offers an ex-cellent orientation to the field of study,particularly for students. The secondsection provides an overview of 1) en-vironmental factors influencing vegeta-ble growth and 2) devices and methodsemployed to control adverse climate foroff-season production. The final sectionpresents a global view of vegetable usageby dividing vegetable crops into twocategories: 1) the starchy roots, tubers,and fruits and 2) the succulent roots,bulbs, tops and fruits. Major vegetablecrops are considered with respect to theirbotany, culture, harvest and storage,nutritive values, economics and pestsand diseases. Clear, black and whitephotographs of most vegetables comple-ment the discussion of the respectivevegetables. The Appendix offers usefulconversion tables and a table describingthe botanical classification, region ofgrowth and climatic adaptation formajor vegetables. The Glossary ofbotanical terms is complete and useful.

The information is necessarilysuccinct, the discussions brief due tothe author’s broad scope and his intentto include vegetables used throughoutthe world. Although the professionalhorticulturalist or researcher interestedin in-depth information about a par-ticular vegetable might find the contentscant, the volume would serve well as asupplement to class lectures for under-graduate students of horticultural sci-ence and as a resource for the seriousamateur gardener. The volume wouldbe particularly useful for extension per-sonnel and agricultural planners every-where. The book should be a standardreference for libraries as a single volumewhich provides easy access to vegetablecrops worldwide as a starting point formore prolific inquiry into specificvegetable crops.

--Eugene BramsCollege of Agriculture

Prairie View A&M University(Texas A&M Univ. System)

Prairie View, TX

Genetic Principles: Human and SocialConsequences--Gordon Edlin. Jonesand Bartlett Publishers, Boston andPortola Valley. 1984. 464 p. Illuso

During the past decade we have seendramatic breakthroughs in the area ofgenetics. Here is a text that presents themost recent discoveries in recombinantDNA technology, gene regulation andexpression, and cell fusion and culture,

in perspective with the classicalgenetics of Mendel.

As the title would suggest, major em-phasis is placed on human genetics;however, I would strongly recommendthis book to agriculturalists. The claritywith which modern concepts and tech-niques in molecular genetics are pre-sented is particularly impressive.

All but three chapters contain 10 ormore self explanatory figures, many ofwhich are excellent diagrams describingan experiment or procedure discussed inthe text. In addition to the numerousdiagrams and photographs there are twoor more inserts, less than two pages inlength, within each chapter. Theseinserts, or "boxes," of information arecomplete in themselves, and are vehiclesfor discussing philosophical or con-troversial views, or in some cases pro-vide additional specific information on atopic in the main body of the text. Toillustrate, a sample of box titles follows:

How did cells arise?Scientific discovery and the prepared

mind.Hair styles: Burning your disulfide

bridges.Constructing gene libraries.Gene splicing: The real concern?The genetic code is universal, but...Should new life forms be patentable?Plant cloning: Potatoes + tomatoes

= Pomatoes.A concise history of the Creation-

versus-Evolution controversy inAmerican public education.

Screening for "cancer resistant"workers.

Student interest and participation inclass discussion is bound to be arousedby these refreshing and often challeng-ing inserts.

For the reader with little or no sci-entific backg~:ound, Chapter 1 lays thefoundation "from atoms, through thestructure of simple and complex mole-cules to the organization of organelles inanimal and plant cells. The followingnine chapters are devoted to the princi-ples of molecular genetics, the structureand function of DNA, recombination,replication, mitochondrial DNA,jumping genes, transcription, transla-tion and protein structure, the geneticcode, mutations and mutagens, cancercells, gene regulation, and recombinantDNA technology.

Mendel’s experiments are deferreduntil Chapter 11, in which the Laws ofSegregation and Independent Assort-ment are discussed. Meiosis is also intro-duced at this stage, as is gene linkageand interaction. Although these topicsmay appear to be given little space in thisbook, their importance is made abund-


antly clear. Each topic is conciselycovered and well integrated with theprevious chapters. The Chi-square test isnot mentioned at all, and appears to bethe only major omission of this book.

Chapters 12 to 14 are devoted ex-clusively to human genetics, coveringsuch areas as sex determination, heredi-tary diseases, genetic screening andcounselling, and in vitro fertilization.These chapters may not seem particular-ly relevant to agronomy majors; how-ever, autosomal recessive and dominantinheritance are discussed together withpolygenic inheritance and genetic load.Supplementation with plant exampleswould be needed here and also in the fol-lowing chapter, Chapter 15, in whichsomatic cell genetics and the manipula-tion of genes in the laboratory arecovered. Monoclonal antibodies are de-

scribed in the next chapter which focuseson antibody-determining genes of theimmune system.

Principles of population genetics areoutlined in Chapter 17 following a dis-cussion of Darwin's Theory of NaturalSelection, which in turn is followed by apresentation of basic scientific dis-coveries in evolutionary biology.

Human and social consequences ofignoring the influence of theenvironment on characteristics such asintelligence or a disease predisposed bymalnutrition provide a thought provok-ing finale to this book in Chapter 19,Nature vs Nurture.

The author's teaching experience isvisible throughout this book.Recognizing the language barrier pre-sented by science, key words are definedin the text, often illustrated in the in-

serts, and redefined at the end of thechapter. Review questions are printed atthe end of each chapter, and theiranswers are given at the back of thebook. In addition, suggestions for essaytopics are provided.

In his Preface Edlin writes, "Thisbook was written in the hope that stu-dents who read it will subsequently beable to distinguish sense from nonsensein the area of genetics. . .." By makinggenetics come alive in his book, Edlinhas succeeded in giving us an excellenttext.

—Mary A. Thomas-ComptonDepartment of Agronomy


CORRECTION

In the Contents page and on p. 61 of the Spring 1984 issue the initialof Dr. Jolliff should be "G." (G. D. Jolliff) not "C." We regret theerror, which occurred as a result of a correction to the title.

(1984) Back Matter (JNRLSE)Lincoln, Lincoln, NE 68583. 2Associate professor of agronomy, Dep. of Agronomy, Univ. of Nebraska-Lincoln, Lincoln, NE 68583-0910. 3 For information on Project

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