Weed dynamics, productivity and soil health under different tillage and weed- control practices in wheat (Triticum aestivum)maize (Zea mays) cropping sequence

A field experiment was conducted during 200910 and 201011 at Rajasthan College of Agriculture, Udaipur, to study effect of 5 tillage systems and 3 weed-control practices on weed dynamics, productivity, and to workout most viable tillage practices in wheat [Triticum aestivum (L.) Emend. Fiori & Paol.]maize (Zea may L.) cropping sequence. Weed density, grain yield of wheat, maize and wheat-equivalent yield were found statistically equal in continuous conventional tillage and adoption of rotated zero tillage in wheat and conventional tillage in maize un- der wheatmaize cropping sequence. Adoption of zero tillage in wheat and conventional tillage in maize also proved economically beneficial with the highest net returns ( 73,868/ha) and benefit: cost ratio (2.11) compared to net returns ( 72,476/ha) and benefit: cost ratio (1: 94) recorded under continuous conventional tillage in both crops. Amongst the weed-control practices, use of isoproturon (0.75 kg/ha) in wheat and atrazine (0.5 kg/ha) fol- lowed by 1 hoeing in maize significantly reduced weed density, dry matter and recorded significantly higher wheatmaize and wheat-equivalent grain and straw yields than 2 hand weedings and weedy check. Application of isoproturon (0.75 kg/ha) in wheat and atrazine (0.5 kg/ha) in maize resulted in the highest net returns of 82,749/ ha and benefit: cost ratio 2.41 and proved significantly higher over 2 hand-weedings by 5,876/ha and benefit: cost ratio 0.43. At the end of 2 cycles adopting zero tillage in wheat and conventional tillage in maize significantly enhanced organic carbon content by 4.0% over continuous conventional tillage; however, did not influence status of available nitrogen and phosphorus significantly in soil. The weed-control practices did not influence available ni- trogen status of soil; however, organic carbon and available phosphorus status of weedy check plots increased significantly over rest of the weed-control treatments.