Response to, and Efficiency of, Different Forms of Fertilizer Nitrogen Applied to an Arid Highly Calcareous Soil.

Abstract

Wheat was grown in pots on a medium-textured, highly calcareous soil. Eight levels of urea, ammonium sulphate and calcium nitrate were applied. No significant difference was obtained on DM yield due to N source. The urea-and the nitrate-treated plants accumulated more total N than the ammonium sulphate-treated ones because of higher dry matter N content; at 333 ppm N the NO3 appeared toxic. Maximum DM yield was attained at a nitrogen application of around 133 ppm, but applications of up to 333 were tolerated by the plants without extra DM yield. The plants generally utilized applied N with an efficiency of around 30-40%, with a tendency to decrease as the rate of application was increased