balkcom_11f

590 A.C. Rocateli et al. / Industrial Crops and Products 36 (2012) 589598

efciency of combustion conversion due to diminished heat transfer (Burner et al., 2009; Sanderson et al., 1996).

Much emphasis has been placed on perennial crops for cellulosic material production. Switchgrass (Panicum virgatum L.) is a reference for combioenergy (may occur icrops (Peterand annualtural land tcrops, whicin the southfor cellulos(Sorghum bibecause larlimited con2004a,b). Hing to deveMastrorilli etended to cmore sensitproductivitfrom Mastrafter sorghugation shoufalls below

Sorghuma crop rotatL.) and cottwould be uharvested fbiomass prosuch as in-rconsidered U.S. conditi

The objesorghum anbiofuel probiomass prtion and coproduction

2. Materia

2.1. Site des

A study years at the(855315011

ously with soil type watypic Kanhaproduced aentire eldbefore plan

2.2. Cultura

Rye wasusing a no-tical conserveach year, t(phosphono

Three sosorghum; G

1990 (photoperiod-sensitive sorghum; PS) (Sorghum Partners Inc., 2011). GS is highly qualied for dairy silage production, due to high grain to forage ratio (1520%), with an average plant height of 2 m (67 feet), excellent standability, very good drought toler

veraty. G witum Paturitandess be u (Sorve s of meae yieSorgh cornast Uionets oftal f(wetideretionte A, 14, d su Extll, 20d wi the o tillentd inKell.40 mor-mur b in ny r, and at 7erfolot aentim

to ametoxy-1satemend irrigrigatof ape plason. istrib mmg. Hr incch a) dalanticomm011)parisons and one of the most probable feedstocks for U.S. DOE, 2005). Negative impacts on food production f conventional crops are replaced with perennial energy s and Thielmann, 2008). Conversely, conventional crops energy crops can be alternated on the same agriculo produce both food and bioenergy feedstock. Annual h have largely been ignored for bioenergy production eastern U.S., could provide a major source of biomass ic bioenergy production. For these reasons, sorghum color L.) may be an alternative energy crop in this region, ge amounts of biomass can be produced in water-ditions (Amaducci et al., 2000; Habyarimana et al., owever, drought resistance of sorghum varies accordlopment stage through the growing season. Studies by t al. (1999) indicated that sorghums drought resistance hange according to development stages. Sorghum was ive to drought stress in early leaf stages where biomass y decreased substantially if water was restricted. Results orilli et al. (1999) showed that stomata closure beings m reached the wilting point (0.4 MPa). Therefore, irrild be used in early growth stages and any time soil water the wilting point. could be integrated in a conservation system as part of ion with cash crops, such as peanuts (Arachis hypogaea on (Gossipyum hirsutum L.), where part of its biomass sed as soil cover and any additional biomass would be or biofuel production. In addition, tillage impacts on duction must be also evaluated. Conservation systems, ow subsoiling combined with a winter cover crop are an alternative to increase crop productivity in southeast ons (Hunt et al., 2004). ctives of our study were therefore: (1) to compare d corn (Zea mays L.) biomass quantity and quality for duction, (2) to determine the effect of irrigation on oduction, and (3) to determine the effect of conservanventional tillage on sorghum and corn for biomass .

ls and methods

cription

was initiated in November of 2007 and conducted for 2 E.V. Smith Research CenterField Crop Unit, Shorter, AL W, 322512211 N). The location had been cropped previcotton for 8 years in a conservation tillage system. The s Marvyn Loamy sand (ne-loamy, kaolinitic, thermic, pludult). In order to maximize the amount of biomass nd provide ground cover during the winter months, the was planted with a rye (Secale cereale L.) cover crop ting corn and sorghum.

l practices and treatments

planted at 100 kg ha1, in early November each year ill drill (Great Plains Mfg. Inc., Salina, KS) following typation cultural practices for the region. In early April he rye cover crop was terminated with glyphosate [Nmethyl) glycine]. rghum hybrids are used in the study: (1) NK300 (grain S), (2) Sucrosorgo506 (forage sorghum; FS) and (3)

ance, amaturivesting(Sorghlate mgood ssweetnit can vestedsensiti20 minhavingtonnagtent) (hybridsoutheence. Pamounhigh tostarch is consproduc

In laof 14, 4(K), anerativeMitchedresseduring

Twimplemreceive(KMC, 0.350a tractThe foseededcompaFS, GSseededwere pAutopiwith ccationof S-methoglyphorecom

Thenon-irsisted providing sea2008 d50 (24plantina wateson, su(25 mmafter ptem reet al., 2ge stalk sweetness (sugar content) and medium early S is therefore important for both greenchop (harhout allowing the biomass to dry) and stalk grazing artners Inc., 2011). In contrast, FS is described as a ng sorghum, with a mean plant height of 3.5 m, very ability, high tonnage yield performance and high stalk (sugar content). FS has limited use for greenchop, but sed for bioethanol production if biomass is dry harghum Partners Inc., 2008a). Finally, PS is a photoperiod orghum (headless), which needs less than 12 h and daylight to produce a grain head. It is described as n plant height of 3.5 m, good standability, very high ld performance and average stalk sweetness (sugar conum Partners Inc., 2008b). Additionally, Pioneer 31G65 (Pioneer, 2011) which is commonly cultivated in the .S. was also included in this study as a point of referer 31G65 is described as suitable for producing large crop residue. The end-use segments for this variety are ermentables (dry-grind ethanol) with high extractable milling) and yellow food corn. Therefore, this variety d a good choice both for grain and cellulosic biomass . pril 2008 and 2009, starter fertilizer was applied at a rate and 5 kg ha1 of nitrogen (N), phosphorus (P), potassium lfur (S), respectively according to the Alabama Coopension System soil test recommendations (Adams and 00). An additional 110 kg N ha1 of UAN (34%) was side th a tractor-mounted liquid applicator in row middles growing season of each year. age systems (conservation and conventional) were ed shortly after fertilization. Conservation plots -row subsoiling with a narrow-shanked subsoiler ey Manufacturing Co., Tifton, GA) to a depth of . Conventional plots were disked and leveled using ounted tandem disk harrow to a depth of 0.15 m. ioenergy crops, including GS, FS, PS, and corn were rows spaced at 0.92 m. Seeding rates were based on ecommendations, which were 407,700 seeds ha1 for PS (Sorghum Partners Inc., 2008a,b, 2011). Corn was 8,300 seeds ha1 (Pioneer, 2011). Tillage and planting rmed with a tractor equipped with a Trimble AgGPS utomatic steering system (Trimble, Sunnyvale, CA), eter level precision. Premergence herbicides appli

ll bioenergy crops in both years were 1.6 kg a.i. ha1

lachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methylethyl) acetamide] with 0.82 kg a.i. ha1 of using a boom sprayer mounted on a tractor at ed carrier and adjuvant concentrations. ation plots were managed with two different regimes: ed (rainfed) and irrigated. The irrigation treatment conplying water in appropriate timing and amounts to nts with adequate water availability during the growIrrigated plots received a water increment of 131 mm in uted in 6 different days, such as 17 (12 mm), 31 (8 mm), ), 63 (32 mm), 77 (30 mm), and 91 (25 mm) days after owever, due to high rainfall the irrigated plots received rement of 58 mm distributed in 3 days during 2009 seas 1 day before planting (14 mm), 21 (19 mm) and 30 ys after planting. Irrigation was terminated at 16 weeks ng in both years. Alabama Cooperative Extension Sysendations were used to apply all insecticides (Flanders .

591 A.C. Rocateli et al. / Industrial Crops and Products 36 (2012) 589598

Grain from NK300 and corn were harvested in late August of each year using a Gleaner G combine (AGCO Company, Duluth, GA). SS506 and 1990 were harvested in late October of each year.

2.3. Data co

2.3.1. WeatCumulat

E.V. Smith RprecipitatioECH2O RaiWA) were i14 WAP). Rrain gaugesPullman, Wtions wherethe other olocated 0.6

Cumulatculated basAlabama Agwere calculcrops. Maxiand sorghu

2.3.2. Rye cRye dry

sorghum forye subsamdried at 55biomass drycollected fothe entire econservatiolected.

2.3.3. PlantSorghum

ber of plantPlant populing season)

2.3.4. PlantFive pla

surements oyears. How18 weeks wafter plantiafter planti

Ten differandomly suppermost tistical anal

2.3.5. AbovAbovegr

was sample14, 20, and in 2009 ratby high preGS were nothose crops

The abovtion in eachcobs, and hand stems.

The wet biomass weights of leaves and stems were recorded. Sub-samples were collected, ground, weighed, and dried at 55 C until constant weight and then used to estimate aboveground dry matter (ADM) and aboveground biomass moisture content (ABMC).

Abov abovc, Stergeell wed us was of ad, l for 8d-detle colub of O of gn, ane susvacu

son l ADFrinsees wees wnin estimen-dry bid toicel

ellul lignmice

perim

energrip-stmesyste exptionsted benerfferelso sgimervati.1 m ll me expdata with intes weonsig botioneanllection

her data ive precipitation for 20082009 and were collected at esearch Center (AWIS, 2011). In addition, cumulative n was monitored during each growing season. Eight n gauges Model ECRN (Decagon Devices, Pullman, nstalled during each growing season (from planting to ain gauges were paired in four sets. Each set had two and an ECH2O logger Model Em5 (Decagon Devices, A). These four sets were placed in different eld loca one rain gauge was installed in an irrigated plot and ne installed in non-irrigated plot. All rain gauges were m from two middle rows. ive in-season growing degree-days (CGDUs) were caled on daily air temperature collected at E.V. Smith ricultural Station (AWIS, 2011). Growing degrees units ated using base temperature of 10 C for all bioenergy mum temperature of 29.4 and 38 C were used for corn m, respectively.

over crop matter samples were collected 1 week prior to planting r both years. A 0.25 m2 frame was used to sample two ples from each experimental unit. Samples were oven-

C until constant weight to determine aboveground biomass yield. In 2008, rye aboveground samples were r all experimental units because rye was cropped across xperimental area. However, rye was just cropped in n plots in 2009 where aboveground samples were col

population and corn populations were calculated from the nums in 1.5 m transects on both middle rows of each plot. ations were determined 6 weeks after planting (grow and 14 weeks after planting (at harvest).

height nt height measurements were made each year. Meaccurred at 6, 9, 14, and 24 weeks after planting in both

ever, in 2008, the fourth time period was performed at hile in 2009, these data were collected at 20 weeks

ng due to rainfall that occurred during the 18th week ng. rent plants in the two middle rows of each plot were elected, and those plants were measured extending the leaves. Mean height of the 10 plants was used for staysis.

eground dry matter and biomass moisture content ound biomass was harvested three times per year. It d 14, 18, and 24 weeks after planting in 2008 and at 24 weeks after planting in 2009. The harvest at 20 WAP her than at 18 WAP (delay in two weeks) was caused cipitation. Aboveground biomass samples for corn and t collected at the 24th week in 2008 and 2009, because were terminated at 18 weeks after planting. eground biomass samples were collected in a 1.5 m sec

of the two middle rows of all experimental plots. Grains, usks were separated from leaves (lamina and sheath)

2.3.6. Dry

Scientitral deplant canalyzsample12 mLwashe105 C

Aciinsolubthe insciationsamplesolutio1 h. Thunder NDF.

Kla1975).tered, residuresidufree lig

To eand ov100% dweighe

HemADF. CKlasonand he

2.4. Ex

Bioin a sttal treatillage

Thereplicaseparathe biotwo diwere ation re(conseunits 9of 4. Aof each

All designand itsregimewere csiderininteracment meground biomass quality eground samples were ground using a Wiley (Thomas wedesboro, NJ) sample mill to pass a 1 mm screen. Neunt ber (NDF), which represents the insoluble matrix of all (holocellulose and lignin) (Robbins et al., 1975), was ing Robertson and Van (1977) procedures. A 0.5 g sub- treated in 100 mL of neutral-detergent solution, and in mylase enzyme solution. The sample was then ltered, tered under vacuum, and dried in a forced air oven at h. Cell wall residues were weighed for calculations. ergent ber (ADF), which is a rough partition of the ell wall into acid-detergent soluble hemicellulose and le lignin and cellulose, was determined using the Assofcial Analytical Chemists method (AOAC, 1975). A 1.0 g round tissue was dissolved in 100 mL of acid-detergent d boiled to keep particles in suspension and reuxed for pended particles were then ltered, washed, and ltered um. ADF yield was determined in the same manner as

ignin was used to determine lignin content (AOAC, material was treated with 24 N sulfuric acid for 3 h, ld, and oven dried at 105 C. Acid detergent lignin (ADL) re weighed and ashed at 450 C. The acid insoluble ash ere weighed and subtracted from ADL to provide ash-stimate. ate ash content, a 1 g sample was placed into a crucible ried at 105 C. The residues were weighed to estimate omass content and ashed at 450 C. The ash residue was calculate ash content (AOAC, 1975). lulose was estimated as the difference between NDF and ose was estimated as the difference between ADF and in. Holocellulose was estimated as the sum of cellulose llulose.

ental design and statistical analysis

y crops, irrigation, and tillage practices were evaluated plit plot design. The four crop varieties were horizonnts. Two irrigation regimes were vertical plots, and two ms were sub-plots. erimental area (84 m long by 60 m) was divided into 4 . Each replication was divided into 4 areas which were y borders 9.1 m long by 3.7 m wide in order to evaluate gy crops: PS, FS, GS, and corn. Plots were divided into nt irrigation regimes (irrigated, non-irrigated), which eparated by borders 9.1 m long by 3.7 m wide. Irriga plots were also divided in two different tillage systems on and conventional) which resulted in 64 experimental long by 3.7 m wide. Experimental units were composed asurements were collected from the two middle rows erimental unit. were analyzed using the appropriate strip-split-plot PROC MIXED of SAS (Littell et al., 1996). Replication ractions with bioenergy crops (crops) and irrigation re considered random effects, and their interactions dered xed. Data were analyzed and discussed conth years, except when signicant year treatment

occurred. In this case, data were analyzed by year. Treats were separated by the LSMEANS procedure (SAS Inst.

593 A.C. Rocateli et al. / Industrial Crops and Products 36 (2012) 589598

Irrigation signicantly affected plant height in both years for all periods (data not shown). Plants in irrigated plots were significantly taller than non-irrigated plants, except at 6 WAP in 2009. Carmi et al. (2006) found similar results for forage sorghum varieties, and Sthat irrigatinicant difffound betwAdditionalltaller than iirrigation wdue to 378 m

Signica18 WAP in gested that not shown)after 14 WAwere still gr

Plants inboth years Omer and Esoil disrupttaller sorgh

Signicain 2008 (daconservatioimproved p rrigation and tillage effects on aboveground dry matter production for all 2009, crops g periods in 2008 and 2009 near Shorter, AL. Different letters denote signif-Results sugg ferences (L.S. means0.1) between treatments within years.

ferent for bboth years. tion potential over long periods (from 18 WAP). On the other

S showed no signicant differences between 18 and 24 WAP 3.5. Aboveg were just signicantly higher than 14 WAP. GS and corn

d theDue to h ition

icant ADM d plyears (P 0year. Yieldstional plotsFig. 2). Simiet al. (1997)than corn foCogle et al.tillage systethan corn. higher ADMP = 0.01). Seferences beamounts ofresulted in bconservatiosuitable forand Marvynpermeable (noted for enand water and Toucht

ADM differences amcalculated fhighest ADMHowever, PAt 24 WAP,30.13 Mg hathat showedother samp

boveground dry matter production in 2008 and 2009 near Shorter, AL. Diftters denote signicant differences (L.S. means0.1) between bioenergy crops pling periods (WAP) within years. akellariou-Makrantonaki et al. (2007) also concluded on resulted in taller sorghum plants. However, no sigerences between irrigation (180 mm vs. 250 mm) were een two different silage sorghums (Yosef et al., 2009). y, plants in non-irrigated plots (1.36 m) were slightly n irrigated plots (1.28 m) at 6 WAP in 2009, because no as needed during the rst 6 weeks during 2009 season m of rainfall.

nt crop irrigation interactions were found at 14 and 2008; and at 14 WAP in 2009. Those interactions sugirrigated GS and corn were shorter than FS and PS (data . Irrigation did not improve GS and corn plant height P, since both varieties were mature while PS and FS owing (vegetative stage). conservation tillage were still growing vegetatively for during all periods, except 24 WAP (data not shown). lamin (1997) suggested that in-row subsoiling (vertical ion) improved soil aeratoin and inltration resulting in um plants. nt crop tillage interactions were found at 6 and 9 WAP ta not shown). Corn was the only crop that was taller in n plots at 6 WAP in 2008. However, conservation tillage lant height for PS, FS, and corn, except GS at 8 WAP. In Fig. 2. I tillage interactions were found at 20 WAP in 2009. samplinested that tillage treatments were not signicantly dif icant dif

oth PS and FS. Similar results were found at 24 WAP for produchand, F

round dry matter which showe

igher precipitation in 2009 than 2008 (Table 1), signif- Adddifferences among crops were found when comparing irrigate.01). Therefore, the results of ADM were analyzed by from conservation plots (18.47 Mg ha1) and conven (18.39 Mg ha1) did not differ in ADM in 2008 (P = 0.87; lar results were found by Shirani et al. (2002) and Angers . All sorghum varieties showed higher ADM production r both years which was similar to results reported by

(1997) who reported no differences among different ms, but also reported sorghum biomass yield higher In 2009, conservation plots (12.26 Mg ha1) showed production than conventional plots (11.02 Mg ha1; veral factors could have inuenced these ADM diftween tillage treatments in 2009, including increased rye cover crop that were produced that could have etter growing conditions for biomass production under n tillage. Conservation tillage was considered more soils which had good drainage (Al-Kaisi et al., 2005), soils were described as well drained, and moderately OSD, 2011). Furthermore, conservation tillage has been hanced plant growth due to increased root proliferation inltration than conventional tillage systems (Reeves on, 1986). fered with year and WAP (Fig. 3). In 2008, ADM difong crops were found when comparing LS means

rom all tillage and irrigation treatments. FS showed the production at 14 WAP, followed by PS, GS and corn.

S surpassed FS at 18 WAP followed by GS and corn. PS showed higher yields than FS with, respectively, 1 and 24.00 Mg ha1. Thus, PS was the only variety signicantly higher ADM production at 24 WAP than at ling periods. Results indicated that PS had high biomass

Fig. 3. Aferent leand sam same yields in both 14 and 18 WAP (P 0.01). ally, irrigated plots had higher ADM yields than nonots in 2008 (Fig. 2; P = 0.01). Because irrigation was

597 A.C. Rocateli et al. / Industrial Crops and Products 36 (2012) 589598

4. Conclusions

Sorghum bioenergy crops yielded more ADM than corn during all sampling periods in both years; and they yielded more than corn with iscenarios, tbiomass. Mtal variationthan 2009 ssouthern crespectivelywhich affecto high planbiomass pro

Irrigatioboth years.conservatiocover foundattributed tby better sp

Biomasscrops than cto be condilulosic biomdifferent amcellulose, li8.3, 2.0, andproduction selecting th

PS was camounts of30.13 Mg haalternative occurs at 1readings claHowever, itphotoperioharvests.

Acknowled

The authand Morris tion of tradsolely for thnot imply rment of Agemployer.

References

Adams, J.F.,Alabama http://ww08.08.11).

Al-Kaisi, M.M.,by tillage s30, 17419

Amaducci, S., parameterNorth of It

Angers, D.A., BVoroney, Rpractices oCanada. So

Association ofsis, 13th e

AWIS Weathe2008/2009

Burner, D.W., Tew, T.L., Harvey, J.J., Belesky, D.P., 2009. Dry matter partitioning and quality of Miscathus, Panicum, Saccharum genotypes in Arkansas, USA. Biomass Bioenergy 33, 610619.

Carmi, A., Aharoni, Y., Edelstein, M., Umiel, N., Hagiladi, A., Yosef, E., Nikbachat, M., Zenou, A., Miron, J., 2006. Effects of irrigation and plant density on yield, com

tion aurity s K.A., Muel comronme.L., Rao997. Sperens, A., el pro, K.L.,rol. Inmana,a. Muities amana,ass soediterG., Baumulatlou, Aer con., OwaceouSout

://ncs8.11)..C., Miels. SAilli, Met sorgth stalin, S, C., V. In: P.J., WiTebeeracno.W., Dhum yeries

at htt8.11)..A., E

blishm, Thiel. EnerHi-brn Hybs://wwLnCd=.W., T

trogen. Soil T, C.T., stion n, J.Bs. J. Anon, Mof bionergyon, Mrse eniou-Mt of mhum (189. H., HajtillageRes. 6 Part

ion. Sners.c Part

ion. Sners.c Part

ion. Sners.cartmeroducrrigation and conservation tillage. In some production hen, sorghum may be superior to corn for cellulosic ost yield parameters exhibited signicant environmen. Higher cellulosic biomass production reported in 2008 eason was related to the presence of anthracnose and orn leaf blight diseases in sorghum and corn crops, . Thus, crop rotation may be recommended. Lodging ted PS, FS and GS sorghum varieties could be related t population. Therefore, sorghum plant populations for duction in the southeastern U.S. should be reevaluated. n positively affected cellulosic biomass production in Higher cellulosic biomass production was noted for n than conventional tillage in 2009. Better rye soil in 2009 (2.57 Mg ha1) than 2008 (0.26 Mg ha1) was o increased rye dry matter production in 2009 caused ring weather conditions. moisture content were higher for sorghum bioenergy orn; however all bioenergy crops, including corn, need tioned to reduce moisture content before storage. Celass quality parameters were only slightly signicantly ong crops for all sampling periods. Variation in holo

gnin, and ash concentration among crops was less than 1.9%, respectively. Therefore, total cellulosic biomass was more important that cellulosic biomass quality for e best crop. onsidered the best tested crop to produce maximum

cellulosic biomass (ADM) which produced 26.04 and 1 at 18 and 24 WAP. However, FS can be a reasonable if a shorter growing season is desired and harvesting 4 weeks after planting (21.27 Mg ha1). Plant height ried that PS had slower development than other crops. s prolonged vegetative stage in the southeastern U.S. d resulted in high cellulosic biomass production in late

gements

ors thank Eric Schwab, Karl Mannschreck, Jarrod Jones, Welch for technical assistance with this project. Mene names or commercial products in this publication is e purpose of providing specic information and does ecommendation or endorsement by the U.S. Departriculture. USDA is an equal opportunity provider and

Mitchell, C.C., 2000. Nutrient Recommendations for Crops. Auburn University, Auburn, AL, Available at

w.ag.auburn.edu/agrn//croprecs/NutrientRecsIndex.html (veried

Yin, X., Licht, M.A., 2005. Soil carbon and nitrogen changes as affected ystem and crop biomass in a cornsoybean rotation. Appl. Soil Ecol. 1. Amaducci, M.T., Benati, R., Venturi, G., 2000. Crop yield and quality s of four annual bre crops (hemp, kenaf, maize and sorghum) in the aly. Ind. Crops Prod. 11, 179186. olinder, M.A., Carter, M.R., Gregorich, E.G., Drury, C.F., Liang, B.C., .P., Simard, R.R., Donald, R.G., Beyaert, R.P., 1997. Impact of tillage n organic carbon and nitrogen storage in cool, humid soils of eastern il Till. Res. 41, 191201.

Ofcial Analytical Chemists (AOAC), 1975. Ofcial Methods of Analyd. Association of Ofcial Analytical Chemists, Washington, DC. r Services Inc. (AWIS), 2011. Weather Information for EV Smith AL: . AWIS Weather Services Inc., Auburn, AL.

posimat

Cassida,Biofenvi

Cogle, AL., 1and

Demirbabiofu

Flanderscont

Habyari2004dens

Habyaribiomin M

Hunt, P.accu

Kessavaund

Lee, DHerbter, http08.0

Littell, RMod

Mastrorswegrow

McLaughferrocrop

Metha, PM., anth

Moore, Jsorg

Ofcial Sable08.0

Omer, Mesta

Peters, J.tries

Pioneer Graihttpprod

Reeves, Dof nicorn

Robbinsdige

Robertsostuff

Sandersysis Bioe

Sandersdive

SakellarEffecsorg181

Shirani, and Till.

Sorghummatpart

Sorghummatpart

Sorghummatpart

U.S. DepBiopnd in vitro digestibility of a new forage sorghum variety, Tal, at two tages. Anim. Feed Sci. Technol. 131, 121132. uir, J.P., Hussey, M.A., Read, J.C., Venuto, B.C., Ocumpaugh, W.R., 2005. ponent concentrations and yields of switchgrass in south central US nts. Crop Sci. 45, 682692. , K.P.C., Yule, D.F., George, P.J., Srinivasan, S.T., Smith, G.D., Jangawad, oil management options for Alsols in the semi-arid tropics: annual nial crop production. Soil Till. Res. 44, 235253. 2008. Biofuels sources, biofuel policy, biofuel economy and global jections. Energy Convers. Manage. 49, 21062116.

Everest, J.W., Paterson, M.G., 2011. Grain sorghum insect and weed : AL Coop. Ext. Sys. 2011, IPM-0429. E., Bonardi, P., Laureti, D., Di Bari, V., Cosentino, S., Lorenzoni, C., ltilocational evaluation of biomass sorghum hybrids under two stand nd variable water supply in Italy. Ind. Crops Prod. 20, 39.

E., Laureti, D., Ninno, M.D., Lorenzoni, C., 2004b. Performances of rghum [Sorghum bicolor (L.) Moench] under different water regimes ranean region. Ind. Crops Prod. 20, 2328. er, P.J., Matheny, T.A., Busscher, W.J., 2004. Crop yield and nitrogen ion response to tillage of a Coastal Plain soil. Crop Sci. 44, 16731681. ., Walters, D.T., 1997. Winter rye as a cover crop following soybean servation tillage. Agron. J. 89, 6874. ens, V.N., Boe, A., Jeranyama, P., 2007. Composition of s Biomass Feedstocks. North Central Sun Grant Cenh Dakota State University, Brookings, SD, Available at ungrant1.sdstate.org/uploads/publications/SGINC1-07.pdf (veried

lliken, G.A., Stroup, W.W., Wolnger, R.D., 1996. SAS System for Mixed S Institute, Cary, NC.

., Katerji, N., Rana, G., 1999. Productivity and water use efciency of hum as affected by soil water decit occurring at different vegetative ges. Eur. J. Agron. 11, 207215. ., Bouton, J., Bransby, D., Conger, B., Ocumpaugh, W., Parrish, D., Taliaogel, K., Wullschleger, S., 1999. Developing switchgrass as a bioenergy erspectives on New Crops and New Uses, 282299. ltse, C.C., Rooney, W.L., Collins, S.D., Federiksen, R.A., Hess, D.A., Chisi, st, D.O., 2005. Classication and inherence of genetic resistance to se in sorghum. Field Crop Res. 93, 19. itmore, M., TeBeest, D.O., 2009. The effects of cropping history on grain ields and anthracnose severity in Arkansas. Crop Prot. 28, 737743. Description (OSD), 2011. Marvyn Series. NRCS, Washington, DC, Availps://soilseries.sc.egov.usda.gov/OSD Docs/M/MARVYN.html (veried

lamin, E.M., 1997. Effect of tillage and contour diking on sorghum ent and yield on sandy clay soil in Sudan. Soil Till. Res. 43, 229240. mann, S., 2008. Promoting biofuels: implications for developing coungy. Policy 36, 15381544. ed International Inc. (Pioneer), 2011. Seed Products & Traits: Corn rids. Pioneer Hi-bred International Inc., Johnston, IA, Available at w.pioneer.com/growingpoint/product info/catalog/TopProducts.jsp? 2011&prodCd=2031G2065&GO=Search (veried 11.08.11). ouchton, J.T., 1986. Effects of in-row and interrow subsoiling and time application on growth, stomatal conductance and yield of strip-tilled ill. Res. 7, 327340. Van Soest, P.J., Mautz, W.W., Moen, A.N., 1975. Feed analyses and with reference to white-tailed deer. J. Wildlife Manage. 39, 6779. ., Van, P.J., 1977. Soest Dietary ber estimation in concentrate feedim. Sci 45, 248254.

.A., Agblevor, F., Collins, F., Johnson, D.K., 1996. Compositional analmass feedstocks by near infrared reectance spectroscopy. Biomass 3, 365376. .A., Wolf, D.D., 1995. Morphological development of switchgrass in vironments. Agron. J. 87, 908915. akrantonaki, M., Papalexis, D., Nakos, N., Kalavrouziotis, I.K., 2007. odern irrigation methods on growth and energy production of sweet var, Keller) on a dry year in Central Greece. Agric. Water Manage. 90,

abbasi, M.A., Afyuni, M., Hemmat, A., 2002. Effects of farmyard manure systems on soil physical properties and corn yield in central Iran. Soil 8, 101108. ners Inc., 2008a. SS506 Hybrid Forage Sorghum, Technical Infororghum Partners Inc., New Deal, TX, Available at http://sorghumom/pdfs/SS506.pdf (veried 19.09.08). ners Inc., 2008b. 1990 Hybrid Forage Sorghum, Technical Infororghum Partners Inc., New Deal, TX, Available at http://sorghumom/pdfs/1990.pdf (veried 19.09.08). ners Inc., 2011. NK300 Hybrid Forage Sorghum, Technical Infororghum Partners Inc., New Deal, TX, Available at http://sorghumom/nk3.php (veried 08.08.11). nt of Energy (DOE), 2005. Biomass as Feedstock for a Bioenergy and ts Industry: Technical Feasibility of a Billion-ton Annual Supply. U.S.

598 A.C. Rocateli et al. / Industrial Crops and Products 36 (2012) 589598

Department of Energy, Oak Ridge, TN, Available at http://www.osti.gov/brigde (veried on 29.04.10).

U.S. Energy Information Administration (EIA), 2011. Petroleum and Other Liquids: U.S. Imports by Country of Origin. U.S. Energy Information Administration, Washington, DC, Available on line with updates at http://www.eia.doe.gov/dnav/pet/pet move impcus a2 nus ep00 im0 mbbl a.htm (veried 08.08.11).

U.S. Environmental Protection Agency (EPA), 2011. Renewable Fuel Standards (RFS). U.S. Environmental Protection Agency, Washington, DC, Available at http://www.epa.gov/otaq/fuels/renewablefuels/index.htm (veried 05.05.11).

Weng, J.K., Li, X., Bonawitz, N.D., Chapple, C., 2008. Emerging strategies of lignin engineering and degradation for cellulosic biofuel production. Curr. Opin. Biotechnol. 19, 166172.

Wilcke, W.F., Cuomo, G., Fox, C., 1999. Preserving the Value of Dry Stored Hay. College of Agricultural, Food, and Environmental Sciences University of Minnesota.

Yosef, E., Carmi, A., Nikbachat, M., Zenou, A., Umiel, N., Miron, J., 2009. Characteristics of tall versus short-type varieties of forage sorghum grown under two irrigation levels, for summer and subsequent fall harvests, and digestibility by sheep of their silages. Anim. Feed Sci. Technol. 152, 111.

Biomass sorghum production and components under different irrigation/tillage systems for the southeastern U.S.1 Introduction2 Materials and methods2.1 Site description2.2 Cultural practices and treatments2.3 Data collection2.3.1 Weather data2.3.2 Rye cover crop2.3.3 Plant population2.3.4 Plant height2.3.5 Aboveground dry matter and biomass moisture content2.3.6 Aboveground biomass quality

2.4 Experimental design and statistical analysis

3 Results and discussion3.1 Environmental conditions3.2 Rye cover crop3.3 Plant population3.4 Plant height3.5 Aboveground dry matter3.6 Aboveground biomass moisture content3.7 Aboveground biomass quality3.7.1 Holocellulose and lignin concentration3.7.2 Ash concentration

4 ConclusionsAcknowledgementsReferences