
%0 Journal Article
%A Wong, M. T. F. 
%A Edwards, N. K. 
%A Barrow, N. J. 
%T Accessibility of subsoil potassium to wheat grown on duplex soils in the south-west of Western Australia
%J Soil Research
%D 2000/05/01
%V 38
%N 3
%P 745-751
%K profile, weighting, response, relative yield, seasonal rainfall, deficiency.
%R https://doi.org/10.1071/SR98117
%U https://www.publish.csiro.au/paper/SR98117 
%X The B horizon of duplex soils in the wheatbelt of Western Australia is sometimes enriched with potassium (K). K supply from this source is, however, not taken into account in fertiliser recommendations based on soil tests on samples from the 0&#8211;10 cm layer. Grain yield responses of wheat to K were measured over 4 years on 10 duplex soils in the medium rainfall (400&#8211;600 mm) regions of the West Australian wheatbelt. The depth at which the texture changed markedly ranged from 25 to 75 cm. K was measured through the profile and the concentration was reduced to a single value with a weighting equation that takes account of the distribution of root length. The weights chosen by the fitting procedure discounted the K content of the subsoil severely and provided no evidence that subsoil K was important in determining yield. Furthermore, the improvement obtained by using the weighted K concentration in the 0&#8211;1 m layer compared with using the topsoil (0&#8211;10 cm) analysis was not statistically significant. K deficiency can be diagnosed in those soils using analysis of the 0&#8211;10 cm samples only. 
