Tillage and weed management in direct-seeded rice (Oryza sativa)–wheat (Triticum aestivum) cropping system

A field experiment was conducted at Ranchi, Jharkhand during 2010–11 and 2011–12, to find out the effect of tillage and weed-control methods on weed dynamics and productivity of rice (Oryza sativa L.)–wheat [Triticum aestivum (L.) emend. Fiori & Paol.] cropping system. The experiment comprised of 4 tillage methods, viz. zero– zero (ZT-ZT), zero–conventional (CT-ZT), conventional–zero (CT-ZT) and conventional–conventional tillage (CT-CT), performed during rainy and winter seasons, respectively laid out under main plots, while 3 weed control methods viz., recommended herbicides in rice (butachlor 1.0 kg/ha pre-emergence + 2,4-D 0.5 kg/ha post-emergence) and wheat (isoproturon 0.75 kg/ha + 2,4-D 0.5 kg/ha post-emergence), weed free and weedy check under subplots. Continuous conventional tillage being similar to rotational tillage systems recorded the maximum rice grain (1.96 t/ha) and straw (2.86 t/ha) yield. Three hand-weedings resulted in 2.25% and 92.38% higher grain yield than recommended herbicidal use and weedy check respectively. The CT-CT tillage being similar to ZT-CT recorded 14.16% higher wheat grain yield (2.85 t/ha) than ZT-ZT tillage. Application of isoproturon @ 0.75 kg/ha + 2,4-D @0.5 kg/ha as post-emergence gave 22.59% and 58.75% higher grain and straw yield than hand-weeding and weedy check respectively. Continuous conventional tillage in rice and wheat recorded 22.18% higher rice-equivalent yield (5.76 t/ha) and maximum net returns ( 28,446/ha). Application of recommended herbicide in rice and wheat gave 11.8% higher rice equivalent yield (6.34 t/ha) than hand-weeding and also provided the maximum net returns ( 37,296/ha) and benefit: cost ratio (1.42).