Isolating the influence of pH on the amounts and forms of soil organic phosphorus

A - Papers appearing in refereed journals

Turner, B. L. and Blackwell, M. S. A. 2013. Isolating the influence of pH on the amounts and forms of soil organic phosphorus. European Journal of Soil Science. 64 (2), pp. 249-259.

AuthorsTurner, B. L. and Blackwell, M. S. A.

Soil pH influences the chemistry, dynamics and biological availability of phosphorus (P), but few studies have isolated the effect of pH from other soil properties. We studied phosphorus chemistry in soils along the Hoosfield acid strip (Rothamsted, UK), where a pH gradient from 3.7 to 7.8 occurs in a single soil with little variation in total phosphorus (mean +/- standard deviation 399 +/- 27mgPkg1). Soil organic phosphorus represented a consistent proportion of the total soil phosphorus (36 +/- 2%) irrespective of soil pH. However, organic phosphorus concentrations increased by about 20% in the most acidic soils (pH<4.0), through an accumulation of inositol hexakisphosphate, DNA and phosphonates. The increase in organic phosphorus in the most acidic soils was not related to organic carbon, because organic carbon concentrations declined at pH <4.0. Thus, the organic carbon to organic phosphorus ratio declined from about 70 in neutral soils to about 50 in strongly acidic soils. In contrast to organic phosphorus, inorganic phosphorus was affected strongly by soil pH, because readily-exchangeable phosphate extracted with anion-exchange membranes and a more stable inorganic phosphorus pool extracted in NaOHEDTA both increased markedly as soil pH declined. Inorganic orthophosphate concentrations were correlated negatively with amorphous manganese and positively with amorphous aluminium oxides, suggesting that soil pH influences orthophosphate stabilization via metal oxides. We conclude that pH has a relatively minor influence on the amount of organic phosphorus in soil, although some forms of organic phosphorus accumulate preferentially under strongly acidic conditions.

KeywordsSoil Science
Year of Publication2013
JournalEuropean Journal of Soil Science
Journal citation64 (2), pp. 249-259
Digital Object Identifier (DOI)
Open accessPublished as non-open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDelivering Sustainable Systems (SS) [ISPG]
Optimisation of nutrients in soil-plant systems: Determining how phosphorus availability is regulated in soils
The Rothamsted Long-Term Experiments including Sample Archive and e-RA database [2012-2017]
Output statusPublished
Copyright licenseCC BY

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