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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!
