Leaf-litter application to a sandy soil modifies phosphorus leaching over the wet season of southwestern Australia

Qiu, S., McComb, A., Bell, R.W. and Davis, J.A. (2005) Leaf-litter application to a sandy soil modifies phosphorus leaching over the wet season of southwestern Australia. Hydrobiologia, 545 (1). pp. 33-44.

Abstract

Nutrient leaching is a critical step in terrestrial litter turnover, and is potentially linked to nutrient cycling in downstream wetlands. Little is known about the leaching behaviour and P loading from terrestrial litter under conditions of winter rainfall in southwestern Australia. In this study, leaf litter of flooded gum (Eucalyptus rudis Endl.), a species common in southwestern Australia, was exposed for leaching under winter rainfall. Litter P was leached primarily during the first few weeks of the wet season, and the ‘first flush’ generating a mean P load of 114.7 mg m−2 from the litter. Thereafter the P leached decreased progressively with the progress of the wet season. Overall, P leaching was correlated with rain intensity, with 84.1% of litter P leached over the wet season May to November. When litter was applied to a bare, sandy soil and then subjected to rain leaching, more P was leached during the ‘first flush’ compared with the data from ‘litter only’ leaching, but a portion of P released from litter and soil appeared to be retained through litter–soil interactions. Litter application to soil surface and via surficial burial reduced leachate P by 25.2–29.5% and 28.6–38.6%, equivalent to a P retention of 75 and 81 mg P m−2, for surface application (10 cm soil) and surficial burial (5 cm soil), respectively. The P retention was attributed to increased microbial immobilisation, supported by increased nutrient flux from litter.