Competitive sorption reactions between phosphorus and organic matter in soil: a review

Abstract

The incorporation of organic matter (OM) in soils that are able to rapidly sorb applied phosphorus (P) fertiliser reportedly increases P availability to plants. This effect has commonly been ascribed to competition between the decomposition products of OM and P for soil sorption sites resulting in increased soil solution P concentrations. The evidence for competitive inhibition of P sorption by dissolved organic carbon compounds, derived from the breakdown of OM, includes studies on the competition between P and (i) low molecular weight organic acids (LOAs), (ii) humic and fulvic acids, and (iii) OM leachates in soils with a high P sorption capacity. These studies, however, have often used LOAs at 1–100 mm, concentrations much higher than those in soils (generally <0.05 mm). The transience of LOAs in biologically active soils further suggests that neither their concentration nor their persistence would have a practical benefit in increasing P phytoavailability. Higher molecular weight compounds such as humic and fulvic acids also competitively inhibit P sorption; however, little consideration has been given to the potential of these compounds to increase the amount of P sorbed through metal–chelate linkages. We suggest that the magnitude of the inhibition of P sorption by the decomposition products of OM leachate is negligible at rates equivalent to those of OM applied in the field. Incubation of OM in soil has also commonly been reported as reducing P sorption in soil. However, we consider that the reported decreases in P sorption (as measured by P in the soil solution) are not related to competition from the decomposition products of OM breakdown, but are the result of P release from the OM that was not accounted for when calculating the reduction in P sorption.

Humic Haplustox under different land uses in a high altitude environment in the Agreste region of Pernambuco, Brazil

“…Ci. Solo, 38:1337Solo, 38: -1349Solo, 38: , 2014 soil acidification by the release of H + (Guppy et al, 2005), which was observed in the surface layers.…”

Phosphate fertilization and phosphorus forms in an Oxisol under no-till

“…), v.67, n.4, p.465-471, July/August 2010 occurred because of the solubilization and migration of phosphates caused by rain water infiltration, as well as due to the mineralization of P-organic following decomposition of cover crops and soybean residues (Bayer and Mielniczuk, 1999;Guppy et al, 2005). A better distribution of soluble P may occur due to an increase in organic P forms resulting from the decomposition of the root systems from preceding crops (Rheinheimer et al, 2000).…”

Adsorção de fósforo em frações argila na presença de ácido fúlvico

“…Guppy et al (2005) relatam que entre os ácidos orgânicos mais ativos à disponibilização de P estão: cítrico, oxálico, glucôncio, lático e málico. Ácidos húmicos e fúlvicos, compostos mais estáveis e de longa persistência na fração orgânica do solo, também podem competir pelos sítios de adsorção.…”