Effects of time, cultivation and urea on nitrogen stress and yield of wheat in a low rainfall area of Western Australia

Abstract

Wheat was grown where nitrogen fertilizer does not usually produce a large increase in grain yield. Urea was applied at sowing at rates from 0-75 kg N per hectare and the crop was sown either after cultivation or without cultivation but with the weed controlled with herbicides-a promising technique for earlier planting. Estimates of weeds and growth, nitrogen content, nitrogen stress, and grain yield of the crop were made at appropriate times. Maximum nitrogen stress occurred during tillering. The response by grain yield to urea was small and could be explained only in part by the relatively low values of nitrogen stress at that time. Where cultivation was replaced by herbicides, nitrogen stress was greater and growth rate, nitrogen uptake and grain yield were lower. Application of 75 kg N/ha at sowing compensated for lack of cultivation during the vegetative stage but did not fully do so for grain yield.