The effect on grain sorghum of depth of placement of initial phosphate fertilizer on new land at Katherine, N.T

Abstract

In an experiment on Tippera clay loam soil at Katherine, N.T., between 1962 and 1965, a comparison was made of the effect of depth of placement of initial applications of superphosphate and Christmas Island rock phosphate dust on the yield of grain sorghum for the first three years of cropping on new land. Placement of 4 cwt an acre superphosphate or 12 cwt an acre rock phosphate in a layer at 8 inches depth gave lower grain, dry matter, and phosphorus yields than mixing the same amount and type of fertilizer in the 0-4 inch or 0-8 inch layers. There were no significant differences in grain, dry matter, or phosphorus yield between mixing in the 0-4 or 0-8 inch layers. Additional annual applications of 4 cwt an acre superphosphate banded with the seed increased grain and dry matter yield when the initial phosphate fertilizer was placed in a layer at 8 inches, but not when it was mixed in the 0-4 or 0-8 inch layers.