Prairie soils, organic matter content

In Prairie silty clay loam (Figure 4), the mobility of all three herbicides was greatly reduced due to the soils high organic matter content (8.2%). Most of the applied radioactivity was found in the upper 10 cm of the column for each compound. 

The proportion of the clay surface in any given soil that is coated by organic substances will depend on organic matter content and the kind and amount of clay. In soils containing exceptional amounts of organic matter, such as many prairie grassland soils, practically all of the clay may be covered with a thin layer of organic matter. 

Soils vary greatly in their organic matter content. A prairie grassland soil (e.g., Mol-lisol) may contain 5 to 6% SOM by mass to a depth of 15 cm, whereas a sandy desert... 

The concentrations of humic and fulvic acids vary considerably from soil to soil, but are closely related to the total organic matter content in the soil. Soil organic matter in well-drained soils ranges from as little as 1.0 wt% or less in coarse-textured soils (Psamments) to more than 6.5 wt% in prairie grassland soils (e.g., Hapludolls) (Soil Survey Staff 1975). Poorly drained mineral soils (aquic suborders), including hydric soils in wetlands, often... 

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