Weed dynamics and productivity of soybean (Glycine max) - based cropping systems as influenced by tillage and weed management

Abstract

A field experiment was conducted during 2001-02 to 2004-05 at Jabalpur to find out the effect of 4 tillage se- quences [zero-till planting of both the crops (ZT-ZT), conventional planting in both the crops (CT-CT), and two rota- tional tillage sequences that altered between zero-till and conventional tillage (ZT-CT and CT-ZT)] and three weed control treatments (weedy check, herbicide alone, and herbicide + 1 hand weeding at 30 days after sowing) on weeds and productivity of soybean ( Glycine max L. Merr.)-based cropping systems, comprising soybean during the rainy ( kharif) and wheat ( Triticum aestivum L. emend. Fiori & Paol.) and linseed ( Linum usitatissimum L.) dur- ing the winter ( rabi). Weeds in weedy check caused 86, 18 and 15.8 % reduction in seed yields of soybean, lin- seed and grain yield of wheat, respectively. Soybean-wheat cropping system produced higher soybean equivalent yield (3.01 t/ha), net returns (Rs 24,318/ha) and B: C ratio (2.17) than soybean-linseed system (1.78 t/ha; Rs 8,709/ha and 1.48, respectively). Zero tillage in both the seasons and effective weed control increased the system productivity as well as profitability. Nearly 50% of the total weed seeds were located in 0-5 cm soil layer. Soybean- linseed cropping system significantly reduced the seed bank of Echinochloa colona but increased the seed bank of Vicia sativa and Chenopodium album. Rotational tillage systems significantly reduced the seed density of E. colona as compared to continuous zero or conventional tillage systems. Weed seed number decreased consider- ably in plots receiving effective weed control (herbicide + 1 hand weeding). Zero tillage with effective weed control was found more remunerative in soybean-wheat system.