Dissolved reactive P plays a minor role in P mobility on contrasting soils from the cropping region of south-west Australia
Sharma, R., Bell, R.W. and Wong, M. (2012) Dissolved reactive P plays a minor role in P mobility on contrasting soils from the cropping region of south-west Australia. In: Joint Australian and New Zealand Soil Science Conference. Soil Solutions for diverse landscapes, 2-7 December 2012, Hobart, Tasmania.
Phosphorus (P) transfer from agricultural land via runoff, throughflow and leaching is of increasing concern for land managers worldwide. Previous studies suggested that organically bound P comprises a large proportion of soil P reserves in south west Western Australia (WA), but the implications of these findings for the processes and rates of P transport in soils are not known. Two contrasting soil profiles (sand and clay) from cropping land of the upper Fitzgerald River catchment in the south coast region of WA were studied in packed boxes to examine the P forms and fluxes in runoff, throughflow, leachate and soil solution after three rates of P application (equivalent to 0, 20 and 40 kg P/ha). Soil solution was collected at 5, 10 and 15 cm depths with inert soil solution samplers, and leachate was collected at the bottom of the 30 cm of packed boxes. Solutions were analysed for particulate P (PP), dissolved reactive P (DRP) and total dissolved P (TDP) while the dissolved uneactive P (DURP) was calculated by difference (TDP-DRP). Phosphorus transport increased with P rate. In the sand, DRP comprised < 35 % of TP in runoff whereas DURP and PP are about 90% of TP in runoff and leachate. In clay soil, 90 % of P losses in DURP and PP form via thoughflow and leaching while DRP constituted < 33 % of total P lost. The result suggested that major portion of mobilized P appeared to be associated with DURP and PP in runoff and leachate in association with dispersed inorganic colloidal compounds < 0.2 mm.
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|Murdoch Affiliation:||School of Environmental Science|
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