Abstract
The aim of this study was to explore the effect of sowing methods and deficit irrigation on weed dynamics, yield and water-use efficiency (WUE) of the maize-cowpea system during the summer and monsoon seasons, respectively. The field experiment was carried out for two years (2015 and 2016) using a split design with three replicates under irrigated (maize) and rainfed (cowpea) conditions on vertisols of a semi-arid region. Treatments included three sowing methods [i.e., broad bed and furrow (BBF), corrugated furrow (CF) and ridges and furrow (RF)] and four irrigation levels [i.e., irrigation once in 10 days (I-10D), irrigation at 40% (I-40), at 50% (I-50) and at 60% (I-60) depletion]. The results indicated that, regardless of weed flora (monocots, dicots and sedges), the RF method produced higher weed density (2.09-2.98 No. m(-2)) compared to CF (2.00-2.80 No. m(-2)) and BBF (1.85-2.64 No. m(-2)) in maize at 30 and 60 days after sowing (DAS). The RF method with irrigation at I-40 and I-50 recorded significantly higher weed density, followed by the CF and BBF method. A similar trend was also observed with dry weight of weeds (monocot; 24.19%, dicot; 25.52%, and sedges; 29.80%) in maize at 30 and 60 DAS. Higher weed density and dry weight of weeds in the RF method with I-40 was due to higher soil moisture availability and higher nutrient uptake due to larger lateral wetting of the soil and greater water use (29.27%). However, the BBF method favoured the growth of weeds (9.33-16.60%) in cowpea at 55 DAS and coped under rain-fed situation over CF and RF. The CF with moderate depletion (I-50) method produced significantly higher maize equivalent yield (MEY) of cowpea (10,000 kg ha(-1)) with considerable reduction in the total water usage (19.33%). Therefore, under a water scarcity situation, growers can practice CF and I-50 for higher yield and WUE of maize-cowpea sequence cropping.