Effect of Methabenzthiazuron, Terbutryne and 2, 4-D on Yield and Nitrogen Removal by Wheat and Associated Weeds¹

A field experiment was conducted during 1975 and 1976 at Agronomy Farm of Indian Agricultural Research Institute, New Delhi to study the effect of herbicides on nitrogen removal by wheat and associates weeds and the experiment results have revealed that grain yield did sot differ significantly between ‘Arjun’ and Sonalika’ in 1975 but in L976 Sonalika was superior to Arjun. Weed control treat-ments caused significant variation in grain yield only in year 1975. Higher levels of nitrogen greater than 40 kg/ha did not prove beneficial. But nitrogen removal by crop and weeds was higher at higher levels of N application as compared to lower level of nitrogen.

At all the stages of crop growth nitrogen removal was higher in 1975 than in 1976. The highest removal was 144.51 kg. N/ha in 1975 Whereas in 1976 the highest removals were only 120 kg N/ha at maturity. In both the years preemergence metha-benzthiazuron gave maximum benefit by arresting nitrogen depletion by weeds as compared to terbutryne, 2, 4-D and hand-weeding. Weed control treatments resulted in maximum saving of 18 kg N/ha by controlling broadleaved weeds.