Weed management and conservation tillage for improving productivity, nutrient uptake and profitability of wheat in soybean (Glycine max)-wheat (Triticumaestivum) cropping system

The effect of tillage, crop establishment and weed management was studied on the performance of wheat grown after soybean at New Delhi, India during 2010-11 to 2011-12. Sixteen treatment combinations involved 2 tillage, viz. conventional tillage (CT) and zero tillage (ZT), two crop establishment practices, viz. raised-bed and flat-bed and four weed management, viz. isoproturon + hand weeding, mesosulfuron+ iodosulfuron, soybean stover + isoproturon and unweeded control. Population density and dry weight of weeds was significantly more under raised-bed than flat-bed, particularly under ZT condition, while under flat-bed, the differences between CT and ZT were on par. Weed control efficiency was the highest (90.7-91.4%) under isoproturon + hand weeding and significantly higher than other treatments (86.5-90.2%). Yield losses under unweeded control were 23.1-26.1%. Grain yield of wheat under ZT-flat-bed (4.46-4.73 ton ha-1) was equal to that under CT-flat-bed (4.44-4.79 ton ha-1), which was comparatively more than raised-bed conditions. All weed control practices were on par and equally effective improving the yield of grain (19.2-27.5%) as well as straw (14.0%) compared with unweeded control. Nutrient uptake by crop decreased linearly with increase in nutrient removal by weeds. The highest net benefit: cost ratio was under ZT-flat-bed and mesosulfuron + iodosulfuron (3.04) followed by soybean stover mulch + isoproturon (2.84). It was concluded that wheat can be grown underzero-till condition with post-emergence herbicide application for realizing higher productivity and profitability in the Indo-Gangentci plains of India.