Uniformity of expressing soil test results a case for calculating results on a volume basis

Abstract

Abstract The assumption of 2,000,000 kg/ha or 2,000,000 lbs/a in the conversion of soil test results into kg/ha and lbs/a introduces variables directly related to the variation in bulk density (BD) or volume weight (VW). In order to obtain enough soil to weigh 2,000,000 lbs/a the depth requirement changes with the VW. A soil with a VW of 1.6 g/cm3 would require a depth of 5.5 inches, 7.9 inches with a VW of 1.0 and 20 inches with a VW of 0.44 g/cm3. A constant soil depth of 20 cm (7.9 inches) is proposed as a standard depth for calculation which in the metric system, corresponds to 2,000,000 dm3/ha. Details relating to the use of the 20 cm standard depth in the metric and U. S. and British systems of weights and measures are discussed.