Leaf litter inputs decrease phosphate sorption in a strongly weathered tropical soil over two time scales

• Published in: Biogeochemistry 2013-05, Vol.113 (1-3), p.507-524
• Main Authors: Schreeg, Laura A, Mack, Michelle C, Turner, Benjamin L
• Format: Article
• Language: English
• Subjects: Acid soils; Ammonium; Animal and plant ecology; Animal, plant and microbial ecology; Bioavailability; Biogeochemistry; Biogeosciences; Biological and medical sciences; Biomass; dissolved organic carbon; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Ecosystems; edaphic factors; Environmental Chemistry; Exact sciences and technology; Forest soils; Fundamental and applied biological sciences. Psychology; Geochemistry; Leachates; leaf extracts; Leaf litter; Leaves; Life Sciences; Marine ecosystems; Organic soils; Phosphates; phosphorus; plant litter; Soil and rock geochemistry; Soil biochemistry; Soil chemistry; Soil environment; Soil microorganisms; Soil organic matter; Soil properties; Soil solution; soil weathering; Soils; Sorption; Surficial geology; Synecology; Terrestrial ecosystems; Throughfall; Tropical environments; Tropical soils
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-012-9781-5

In strongly weathered soils, leaf litter not only returns phosphorus (P) to the soil environment, it may also modify soil properties and soil solution chemistry, with the potential to decrease phosphate sorption and increase plant available P. Using a radioactive phosphate tracer (³²P) and 1 h laboratory incubations we investigated the effect of litter inputs on phosphate sorption over two time scales: (1) long-term field litter manipulations (litter addition, control and litter removal) and (2) pulses of litter leachate (i.e. water extracts of leaf litter) from five species. Leachate pulse effects were compared to a simulated throughfall, which served as a control solution. Soil receiving long-term doubling of leaf litter maintained five-fold more phosphate in solution than the litter removal soil. In addition to the quantity of phosphate sorbed, the field litter addition treatment decreased the strength of phosphate sorption, as evaluated through extraction of sorbed ³²P using a weakly acidic ammonium fluoride solution (Bray 1). In litter removal soil, leachate pulses significantly reduced phosphate sorption in comparison to the throughfall control for all five species evaluated. However, the ability of leachate pulses to reduce phosphate sorption decreased when soil had received field litter inputs. Across soils the effect of leachate pulses on phosphate sorption increased with net sorption of dissolved organic C, with the exception of leachate from one species that had a higher index of aromatic C concentration. These results demonstrate that litter inputs, as both long-term inputs and short-term leachate pulses, can decrease the quantity and strength of phosphate sorption, which may increase the biological availability of this key nutrient.