Integrated weed management for system productivity and economics in soybean (Glycine max)-wheat (Triticum aestivum) system
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A field experiment was conducted at New Delhi during 2006–07 and 2007–08 to find out the effect of soil solarization, 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.]-wheat (Triticum aestivum L. emend. Fiori & Paol.) cropping system. Soil solarization followed by (fb) glyphosate at 1.0 kg/ha reduced the density 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 K/ha) with concurrent lower uptake by weeds (2.6 kg N, 0.5 kg P and 3.3 kg K/ha). It also recorded 61.2% higher soybean seed yield and 28% higher wheat yield compared with those of farmers’ 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 K/ha) by weeds and highest nutrient uptake (85.5 kg N, 10.5 kg P and 38.2 kg K/ha) by soybean. It recorded 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). Imazethapyr 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 kg/ha being superior in weed control and system productivity proved to be a beneficial practice in soybean-wheat system, but owing to its high cost was not as economical as the smother crop.
Cowpea, Deep disking, Glyphosate, Imazethapyr, Sesbania, Soil solarization, Soybean, Weed, Wheat.