Abstract
Intercropping can improve crop productivity through increased water use efficiency (WUE). However, limited information exists to support its adoption and subsequent management. In such instances, crop models can be used as decision support tools to complement data from field trials. The Agricultural Production Systems Simulator Model (APSIM) was used to develop best management practices for improved yield and WUE for a sorghum–cowpea intercrop system for 5 sites in KwaZulu-Natal, South Africa: Richards Bay, Umbumbulu, Deepdale, Wartburg and Ukulinga. Each site represented 1 of 5 different bio-resource units. Planting dates (trigger season climate method, modelling and fixed date approaches), fertilizer rates (0, 50 and 100% recommended N rate), plant population (50% less and 50% more, for either sorghum or cowpea) and irrigation (deficit irrigation and rainfall-based approaches) were considered. In Deepdale, planting dates generated by the model gave high (952.2±85 and 326.3±68 kg∙ha-1) and stable yields for sorghum and cowpea, respectively. Adding 100% fertilizer improved both yield and WUE of the intercrop by 18.5 and 5.1%, respectively, in Umbumbulu and Wartburg. Across all environments, sorghum and cowpea plant populations of 39 000 and 13 000 plants∙ha-1, respectively, increased yield (26.11%) and WUE (15.54%) of the intercrop system. Deficit irrigation was more effective resulting in yield (12.84%) and WUE (11.09%) improvements. It is concluded that APSIM can be used to develop best management practices to assist in developing guidelines for improving productivity of intercrop systems under water-scarce conditions. Keywords: best management practices, yield, water use efficiency
Highlights
Despite moderate progress in yield improvements, crop productivity in rainfed rural agricultural systems remains low and cannot provide food security for current and future demands (Dile et al, 2013; Vanlauwe et al, 2014)
Low yields observed for Deepdale for both sorghum and cowpeas could be due to the overall low rainfall at this site, while high yields observed for Umbumbulu, Richards Bay and Ukulinga were attributed to high rainfall received at these sites
Agricultural Production Systems Simulator Model (APSIM) was efficient at assessing yield responses for sorghum– cowpea under different management scenarios for 5 rainfed agro-ecologies in KwaZulu-Natal
Summary
Despite moderate progress in yield improvements, crop productivity in rainfed rural agricultural systems remains low and cannot provide food security for current and future demands (Dile et al, 2013; Vanlauwe et al, 2014). Besides socio-economic and bio-physical conditions, it has been observed that climate change and variability has resulted in a shift and change in duration of growing seasons, and increased incidences of seasonal dry spells and drought (Rosegrant et al, 2014) This has directly reduced agricultural water resources with an increase in water-scarce areas, and with formerly water-scarce regions becoming water stressed (Schilling et al, 2012). Given this scenario, farmers may not be equipped with the necessary risk management skills to adapt to the effects of climate change and variability (Venkateswarlu and Shanker, 2009). Researchers have, been tasked with coming up with relevant, innovative and practical adaptation strategies that are sustainable and resilient under water scarcity and stress
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