Phosphorus 2 valence sulfide

The chemical form and nature of the element. Most trace metal cations have a low mobility in soils because they adsorb strongly on minerals and organic matter, or form insoluble precipitates (e.g., oxides, carbonates, sulfides). Some elements that take the form of anions in soils, such as boron, are relatively mobile. Other elements that form anions, like phosphorus, are considered to be immobile because they form insoluble precipitates and bond strongly with mineral surfaces. In Figure 9.4, many of the elements of interest in soils are classified on the basis of their ionic radii and valence. The elements tend to fall naturally into one of foiu groups ... 

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