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Re: [SANET-MG] Phosphorus availability (was Loss of Minerals)



Actually, phosphorous (phosphate) exists in the soil as an anion and is
not held at cation exchange sites. However, instead of being leached out
of the soil it forms water-insoluble compounds with other minerals,
depending on pH.  Phosphorous uptake is 500% or so higher from organic
matter than from the mineral soil.
Heide

Lawrence F. London, Jr. wrote:




I think that is the key to understanding P nutrition and the role of
mycorrhizae.  P tends to be adsorbed on soil particles rather than in
solution.


That must be what he told me that I forgot, P adsorbed on soil particles.

> Unlike most minerals that are swept up in bulk uptake of

water by the roots, P does not move much in soil water.  The root
system must go and extract it.  But the root system is not big enough,
hence the niche for mycorrhizae, which can intimately explore far more
surface area of soil particles than can roots, especially early in the
season.



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