Integrated Effect of Deficit Irrigation and Sowing Methods on Weed Dynamics and System Productivity of Maize–Cowpea Sequence on Vertisols

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 (I10D), irrigation at 40% (I40), at 50% (I50) and at 60% (I60) 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 I40 and I50 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 I40 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 (I50) 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 I50 for higher yield and WUE of maize–cowpea sequence cropping.

Evaluation of Emergence and Growth Response of Cyperus Rotundus as Influenced by Sowing Depths and Water Regimes

“…A deficit moisture regime might have reduced the water uptake of weeds (Abouziena et al, 2014), as reported in this study (Figure 2c,3b,and 4b). Similarly, accumulation of dry weight of weed increased with improved soil moisture availability (Halli et al, 2021), as observed in this study (Figure 2c,3b,and 4b). Furthermore, in the peanut deficit, the irrigation from 100 to 40% declined by 25.66% weed dry weight (El-Metwally et al, 2020).…”

“…Increasing the deficit irrigation level drastically reduced EI, FEP (Figure 1b-c) and growth parameters (Figure 2, 3, 4). (Halli and Angadi, 2017) and (Halli et al, 2021) reported that appropriate moisture deficit is a viable option to suppress the weed and reduce water losses. Deficit irrigation of 24 to 40% less water can maintain productivity by suppressing weed competition (Coolong, 2013).…”

“…It is because a plant's nutrient uptake depends on its water uptake ability. A higher degree of deficit irrigation can lead to lower uptake of NPK and poor mineralization, resulting in lower accumulation of weed dry weight (Li et al, 2007;Halli et al, 2021, Hasnain et al, 2021. Irrigation management is an important strategy for controlling and suppressed weed growth.…”

“…Therefore, irrigation management with little stress should be promoted for good crop yield and lesser weed infestation. Deficit irrigation practices can mitigate the competitive effect of weeds with crops (Halli et al, 2021).…”

“…Irrigation level influenced the weed density and biomass (Saudy et al, 2020). The population of weed species was also influenced by deficit irrigation (Halli et al, 2021;Le and Morell, 2021). The interference and yield losses from C. rotundus are so high that some farmers focus on abandoning their fields using a moldboard plough (deep tillage) to combat its population.…”