Pronounced surface stratification of soil phosphorus, potassium and sulfur under pastures upstream of a eutrophic wetland and estuarine system

Ryan, M. H., Tibbett, M. ORCID: https://orcid.org/0000-0003-0143-2190, Lambers, H., Bicknell, D., Brookes, P., Barrett-Lennard, E. G., Ocampo, C. and Nicol, D. (2017) Pronounced surface stratification of soil phosphorus, potassium and sulfur under pastures upstream of a eutrophic wetland and estuarine system. Soil Research, 55 (7). pp. 657-669. ISSN 1838-675X doi: 10.1071/SR16144

Abstract/Summary

High concentrations of nutrients in surface soil present a risk of nutrient movement into waterways through surface water pathways and leaching. Phosphorus (P) is of particular concern because of its role in aquatic system eutrophication. We measured nutrients under annual pastures on a beef farm and a dairy farm in the Peel–Harvey catchment, Western Australia. Soils were sampled in 10-mm increments to 100mm depth in March, June and September. Plant litter contained approximately 300–550 mg kg–1 Colwell-extractable P. Extractable soil P was strongly stratified, being approximately 100–225 mg kg–1 (dairy) and 50–110 mg kg–1 (beef) in the top 10mm and <40 mg kg–1 at 40–50mm depth. Total P and extractable potassium were also highly stratified, whereas sulfur was less strongly stratified. Shoot nutrient concentrations indicated that nitrogen was often limiting and sulfur was sometimes limiting for pasture growth: concentrations of P were often much greater than required for adequate growth (>4mg g–1). We conclude that high P concentrations at the soil surface and in litter and shoots are a source of risk for movement of P from farms into waterways in the Peel–Harvey catchment.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/73303
Item Type	Article
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Soil Research Centre Life Sciences > School of Agriculture, Policy and Development > Department of Sustainable Land Management > Centre for Agri-environmental Research (CAER)
Publisher	CSIRO Publishing
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