Evaluation of rapid tests for assessing nitrogen availability in wheat soils. 1. Correlation with plant indices of availability obtained in pot culture

Abstract

An evaluation of biological and chemical tests of potentially available soil nitrogen has been made using soils important in the wheat producing areas of Australia. Assessment was based on comparison with pot culture data obtained in two consecutive years. Three biological and four chemical procedures were shown to provide equally good indices of the availability of nitrogen to wheat for the black earth soils, the red brown earths and the combined grey and brown soils of heavy texture as well as for all soils used in each year. These results differ from the conclusions of past studies, in which one procedure was usually preferred. Four other tests were not recommended. Significant differences were found among the regression coefficients for individual great soil groups for several tests examined. The implications of this finding in terms of the practical use of such tests are discussed.