Abstract

Results of a five year field trial in a permanent layout showed that no more then 100 per cent replenishment of nitrogen removed by weeds was necessary to reduce weed competition. Increasing rates of simazino significantly increased maize yield but since it tended to decrease wheat yields, half a kilogram of simazine as pre-emergence rear- ment was the best treatment vis-a-vis treedom from harmful residual effect of higher rates on wheat. Pre+post-emergence application providing 0.5 kg 2,4-D/ha along with replenishment of 100 per cent N removed by weeds was the most beneficial treatment. Increase in maize yield and reduction in weed dry matter production with the use of simazine at half a kg/ha rate were 4.2 and 13.2 g/ha. respectively without harmful effect on wheat.

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