Nonagricultural Soil Chemistry

The persistence through many centuries of the temples at Angkor Wat in Southeast Asia depends on the high concentrations of iron and aluminium oxides in the soils used to form the building blocks. Such laterite (now more properly called plinthite) materials from soil can dry irreversibly and thus resist slaking and weathering even in a humid tropical climate. 

Many iron and aluminium ore deposits are the end result of long and extreme soil chemical weathering at the end of the plinthite stage. The lime scale puts their formation into the category of geochemistry, but the mode of formation involves the same chemical reactions as soil formation. 

Chemical pollution is the diversion of chemical elements from the natural biogeo-chemical cycles. The carbon, nitrogen, and phosphate in municipal wastes released to streams and lakes are removed from the soil-plant cycle, which is the source of the nitrogen and much of the phosphate. If those substances were instead put back directly into the soils from whence they came, much less pollution would result. Air and water only slowly convert their wastes back into their natural sites in plants and soils. Soil, on the other hand, has enormous surface area and microbial catalytic activity plus oxygen and water with which to deactivate pollutants. Soil degrades most 

If one considers pollution to be the rendering of soils to be unlit for plant growth, then the greatest contribution to pollution is the salinization and urbanization of soils. Careless irrigation slowly adds increasing amounts of salts to soil, which can reduce and stop plant growth. Covering soils with asphalt and concrete also renders soil unfit for plant production. 

Consumption is the transformation of matter and energy into less useful forms, including dilution to concentrations less than those recoverable by our current technology. Fertilizers, for example, are made from concentrated sources and diluted by spreading on agricultural lands. Over the short term, only a fraction is recovered by plants. The remainder is consumed by the soil when the fertilizer is converted into slowly recoverable or nonrecoverable forms. Not one atom is lost by this consumption, but the availability, chemical states, concentrations, and locations of the atoms change. 

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