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

2 Soil

3 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.

4 composition of soil by volume Ideal fertile soil  Mineral 45%  Organic matter 5%  Water 25%  Air 25%

5 soil particle Rock and mineral weathering Parent material Soil formation Soil particle physical chemical biological Primary particle Secondary particle

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7 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 < mm

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9 soil particle Size mm Minerals (%) SiO 2 Al 2 O 3 Fe 2 O 3 CaOMgOK2OK2ONa 2 OP2O5P2O5 1~ ~ ~ ~ < The larger the particles are, the more SiO 2 the soil has, the more barren it is.

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12 Soil typesSoil texture clay loess silt, with small amount of clay and sand loamsand, silt, clay

13 Clay  Mineral: Al 2 [(OH) 4 Si 2 O 5 ] · nH 2 O Al 2 O 3 · 2SiO 2 · 2H 2 O etc.  poor aeration and drainage  plastic when wet, when dry become firm

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15 Clay is only good for paddy rice field.

16 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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19 loam  mixture of clay, silt and sand  sandy, plastic when wet  easily water contain  more nutrients than sandy soils  ideal fertile soil

20 other parameters  organic matter  pH value etc.

21 organic matter  microorganism  soil animal  organic manure

22 organic matter element: 90~95% C 、 O 、 H 、 N 、 P 、 K 、 Ca 、 Mg 、 Fe 、 Si 、 Zn 、 Cu 、 B 、 Mo 、 Mn etc. soil fertility: soil fertility low low- medium medium high- medium high OM （ % ） <0.50.5~1.01.0~1.21.2~1.5>1.5

23 soil pH value  climate: high temperature and humidity accelerates the weathering  microorganism: for example: breath from bacterium  environment: acid rain

24 The best pH value for plants is 6,5. in soilpHin soilpH Na 2 CO 3 NaHCO 3 MgCO 3 CaCO 3 CaCO 3 -withCO 2 Ca(HCO 3 ) 2 12~13 8.5~ ~8.4 CaSO 4 H 2 O Na 2 SO 4 ， MgSO 4 ， NaCl ， MgCl 2 NH 4 Cl H 2 CO 3 KAl(SO 4 ) 2 ； AlCl ~ ~6.5~ ~5.7 2~4 soil pH value

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26 Fruit PLANT TYPESOIL pH Apple Apricot Arbor Vitae Blueberry, high bush Cherry, sour Cherry, sweet Crab apple Cranberry, large Peach Pineapple Raspberry, red Strawberry

27 Vegetables PLANT TYPESOIL pH Asparagus Beets, table Broccoli Cabbage Carrot Cauliflower Celery Cucumber Lettuce Muskmelon Onion Potato Rhubarb Spinach Tomato

28 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

29 Reference 1. C.Y.Huang, Soil Science, J. Bachmann, G. Arye, M. Deurer, S. K. Woche, R. Horton,Y. Chen, J. Plant Nutr. Soil Sci. 2006, 169, 745–

30 Thank you for your attention!