Integrated weed management for system productivity and economics in soybean (Glycine max)-wheat (Triticum aestivum) system

Abstract

A field experiment was conducted at New Delhi during 2006-07 and 2007-08 to find out the effect of soil solar- ization, deep disking, smother crop (cowpea), glyphosate, imazethapyr and Sesbania mulch on the infestation of weeds and the productivity and profitability of soybean [Glycine max (L.) Merr.]iiwheat (Triticum aestivum L. emend. Fiori & Paol.) cropping system. Soil solarization followed by (fb) glyphosate at 1.0 kg/ha reduced the den- sity and dry weight of weeds by 85% in soybean and 65% in wheat. It, therefore, resulted in considerably higher uptake of nutrients by soybean (92.5 kg N, 11.7 kg P and 34.3 kg Wha) with concurrent lower uptake by weeds (2.6 kg N, 0.5 kg P and 3.3 kg Wha). It also recorded 61.2% higher soybean seed yield and 28% higher wheat yield compared with those of farmersi practice (one summer ploughing). Two hand weedings among rainy-season treatments proved most superior in terms of lowest density, dry weight and nutrient uptake (2.4 kg N, 0.45 kg P and 3.1 kg Wha) by weeds and highest nutrient uptake (85.5 kg N, 10.5 kg P and 38.2 kg Wha) by soybean. It re- corded 41.3% more soybean seed yield than the unweeded control, but incurred the highest cost of cultivation (Rs 26,643). On soybean-wheat system basis, soil solarization fb glyphosate at 1.0 kg /ha incurred the highest cost of cultivation (Rs 31,519), but controlled weeds effectively and recorded the highest system productivity. However, the net income (Rs 59,926) and benefit : cost ratio (2.5) were the highest in smother crop (cowpea). lmazethapyr as a follow-up treatment in the rainy season provided the highest benefit :cost ratio (1.66). Thus, soil solarization fb glyphosate at 1.0 kglha being superior in weed control and system productivity proved to be a beneficial prac- tice in soybean-wheat system, but owing to its high cost was not as economical as the smother crop.