Estimations of sampling intensities for the characterization of soil within experiment sites

Abstract

Estimates are made of the desirable number of soil core samples that should be taken from the sites of field experiments for the estimation of profile trends in chemical properties for between site comparisons. The estimates are made on the basis of the magnitude of within site variance relative to between site variance. Fewer samples are required when between site variance is high than when it is low. The data were obtained from the sites of experiments representing four great soil groups in southern New South Wales. The desirable number of samples varies amongst the soil groups, with the chemical properties and with depth down the soil profile. Estimates for mean profile trends and for the means of individual depth strata were similar, It is concluded that at least 9 to 12 core samples should be taken per site and preferably 29 to 40 to ensure reasonably safe estimates of profile trends in important chemical properties.