Clay, loess & loam - what is good soil ? Yana Wang 17.01.2007.

Clay, loess & loam - what is good

soil ?

Yana Wang17.01.2007

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Soil

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Soil Science Society of America (SSSA)

Soil is the unconsolidated mineral material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants.

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composition of soil by volume

Ideal fertile soil Mineral 45% Organic matter 5% Water 25% Air 25%

http://jpkc.snnu.edu.cn/geog/webasp/kj/kejian/6%20turangquan.ppt

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soil particle

Rock and

mineral

weathering Parent material

Soil formation Soil particle

physical

chemical

biological

Primary particle

Secondary particle

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classification systems of soil

Criterion: equivalent diameter or effective diameter of

soil particle

Soil texture: gravel >2 mm

sand 0.05~2 mm

silt 0.002~0.05 mm

clay < 0.002 mm

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http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/2.1.ppt

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soil particle

Size

mm

Minerals (%)

SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O P2O5

1~0.2 83.92 9.34 1.12 1.79 0.38 1.78 1.21 0.08

0.2~0.04 73.87 13.47 4.21 3.05 1.05 1.73 1.53 0.12

0.04~0.01 70.15 14.04 5.86 2.15 1.05 1.48 3.89 0.21

0.01~0.002 67.21 18.91 7.85 1.45 1.63 2.51 1.27 0.29

<0.002 44.08 27.67 21.81 0.58 1.61 1.10 0.96 0.36

The larger the particles are, the more SiO2 the soil has, the more barren it is.

http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/2.1.ppt

10http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/2.1.ppt

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http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/2.1.ppt

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Soil types Soil texture

clay clay

loesssilt, with small amount of clay and sand

loam sand, silt, clay

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Clay

Mineral: Al2[(OH)4Si2O5] · nH2O

Al2O3 · 2SiO2 · 2H2O etc.

poor aeration and drainage

plastic when wet, when dry become firm

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Clay is only good for paddy rice field.

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loess

Mineral: most carbonates

small amount of clay minerals

good aeration, water-holding ability

easy to be transported by river and wind

for example: 1935 dust storm in midwest United States

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loam

mixture of clay, silt and sand sandy, plastic when wet easily water contain more nutrients than sandy soils ideal fertile soil

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other parameters

organic matter

pH value

etc.

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organic matter

microorganism soil animal organic manure

http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/3.1.ppt

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organic matterelement:

90~95% C、 O、 H、 N、P、 K、 Ca、Mg、 Fe、 Si、

Zn、 Cu、 B、Mo、Mn etc.

soil fertility:

soil fertility

lowlow-

mediummedium

high-medium

high

OM（%） <0.5 0.5~1.0 1.0~1.2 1.2~1.5 >1.5

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soil pH value

climate: high temperature and humidity accelerates the

weathering

microorganism: for example: breath from bacterium

environment: acid rain

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The best pH value for plants is 6,5 .

in soil pH in soil pH

Na2CO3

NaHCO3

MgCO3

CaCO3

CaCO3-withCO2

Ca(HCO3)2

12~13

8.5~9.5

11.47

10.20

8.48

6.13~8.4

CaSO4H2O

Na2SO4，MgSO4，NaCl ， MgCl2NH4ClH2CO3

KAl(SO4)2；AlCl3

7.0

7.7~7.1

6.3~6.5~6.8

4.7

3.9~5.7

2~4

soil pH value

http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/5.1.ppt

25http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/5.1.ppt

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FruitPLANT TYPE SOIL pH

Apple 5.0-6.5

Apricot 6.0-7.0

Arbor Vitae 6.0-7.5

Blueberry, high bush 4.0-5.0

Cherry, sour 6.0-7.0

Cherry, sweet 6.0-7.5

Crab apple 6.0-7.5

Cranberry, large 4.2-5.0

Peach 6.0-7.5

Pineapple 5.0-6.0

Raspberry, red 5.5-7.0

Strawberry 5.0-6.5

http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/5.1.ppt

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Vegetables

PLANT TYPE SOIL pH

Asparagus 6.0-8.0

Beets, table 6.0-7.5

Broccoli 6.0-7.0

Cabbage 6.0-7.5

Carrot 5.5-7.0

Cauliflower 5.5-7.5

Celery 5.8-7.0

Cucumber 5.5-7.0

Lettuce 6.0-7.0

Muskmelon 6.0-7.0

Onion 5.8-7.0

Potato 4.8-6.5

Rhubarb 5.5-7.0

Spinach 6.0-7.5

Tomato 5.5-7.5 http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/ppt/5.1.ppt

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Summary

Clay: perfect water-holding ability good for paddy rice field Both loess and loam can be tillable soil for

most of plants. But loam is better, because of more nutrient. more than 1.5% organic matter pH value by 6.5

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Reference

1. C.Y.Huang, Soil Science,1991

2. J. Bachmann, G. Arye, M. Deurer, S. K. Woche, R. Horton,Y. Chen,

J. Plant Nutr. Soil Sci. 2006, 169, 745–753

3. http://netc.nwsuaf.edu.cn/jingpin/2003/turangxue/html/link.html

4. http://soil.gsfc.nasa.gov/soilform/deposits.htm

5. http://nhjy.hzau.edu.cn/kech/2006/turangxue/dzja.html

6. http://en.wikipedia.org/wiki/Clay

7. http://en.wikipedia.org/wiki/Loess

8. http://en.wikipedia.org/wiki/Loam

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Thank you for your attention!