Effect of Straw Burning and Depth of Ash Incorporation on the Efficacy of Isoproturon against Phalaris minor Retz. in Wheat

Field experiments were carried out from 1995–96 to 1997–98 to study the effect of ash obtained by burning 5, 10 and 15 t/ha of rice straw and its incorporation at 0–5, 0–10 and 0–15 cm soil depths on the bioefficacy of isoproturon. A decrease in bioefficacy of isoproturon was observed by increasing the quantity of ash obtained by burning rice straw from 5 to 15 t/ha and by decreasing incorporation depth from 0–15 to 0–5 cm. On an average no ash (control) treatment gave 27.3, 26.9 and 35.5% more yield than the crop raised by shallow incorporation (0–5 cm) of ash obtained by burning 5,10 and 15 t/ha of rice straw: respectively. Similarly, N uptake by crop decreased with increase in ash quantity and with decrease in depth of incorporation.