Info

n2o rock derived, which severely restricts its input rate and makes it depletable (Walker and Syers, 1976). In highly weathered soils, where P is no longer supplied from the parent material, dust deposition may represent the majority of P inputs (Vitousek, 2004). The soil P cycle has been represented in several forms, depending on the particular emphasis used by the author (e.g., soil solution P, soil-plant relations, or microbially mediated P transformations). In Fig. 15.3, soil solution P is placed in the central position, and the P cycle is divided into two subcycles: a biological one in which pools are defined in terms of biological constituents or stability and transfers are primarily microbially mediated, and a geochemical subcycle in which pools are defined in terms of chemical or mineralogical composition and transfers are primarily abiotic. While soil P is not particularly mobile, some losses from soil in dissolved organic form have been observed in highly weathered soils and were found to be of a magnitude similar to that of inputs (Vitousek, 2004). Unlike C and N, phosphorus does not show large biologically mediated fluxes to and from the atmosphere, nor does it serve as a primary energy source for microbial oxidations. Nevertheless, soil organisms are intimately involved in the cycling of soil P. They participate in the solubilization of inorganic P and in the mineralization of organic P. They are also important in the immobilization of available soil P.

Organic Gardeners Composting

Organic Gardeners Composting

Have you always wanted to grow your own vegetables but didn't know what to do? Here are the best tips on how to become a true and envied organic gardner.

Get My Free Ebook


Post a comment