Strategic double cropping on Vertisols: A viable rainfed croppingoption in the Indian SAT to increase productivity and reduce risk
Impact factor: 2.8 (Year: 2015)
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V. NageswaraRao, Holger Meinke, Peter Craufurd, David Parsons, Martin Kropff, Niels Anten, Suhas Wani, T. J. Rego. (30/11/2015). Strategic double cropping on Vertisols: A viable rainfed croppingoption in the Indian SAT to increase productivity and reduce risk. European Journal of Agronomy, 62, pp. 26-37.
tOur study suggests the possibility for transformational change in the productivity and risk profile of someof India’s rainfed cropping systems. In the semi-arid regions of Southern India, farmers traditionally cropsorghum or chickpea on Vertisols during the post-rainy season, keeping the fields fallow during the rainyseason. This practice avoids land management problems, but limits the potential for crop intensifica-tion to increase systems productivity. A long-term (15 year) experiment at ICRISAT demonstrated thatcropping during the rainy season is technically feasible, and that grain productivity of double croppedsorghum + chickpea (SCP–SCP) and mung bean + sorghum (MS–MS) sequential systems were higher thantheir conventional counterparts with rainy season fallow, i.e. fallow + post-rainy sorghum (FS–FS) and fal-low + post-rainy chickpea (FS–FCP). Without N application, mean grain yield of post-rainy sorghum in theMS–MS system was significantly greater (2520 kg ha−1per two-year rotation) than in the FS–FS system(1940 kg ha−1per two-year rotation), with the added benefit of the mung bean grain yield (1000 kg ha−1per two-year rotation) from the MS–MS system. In the SCP–SCP system the additional grain yield ofrainy sorghum (3400 kg ha−1per two-year rotation) ensured that the total productivity of this systemwas greater than all other systems. Double cropping MS–MS and SCP–SCP sequential systems had sig-nificantly higher crop N uptake compared to traditional fallow systems at all rates of applied nitrogen(N).The intensified MS–MS and SCP–SCP sequential systems without any N fertilizer applied recorded amuch higher median gross profit of Rs. 20,600 (US $ 375) and Rs. 15,930 (US $ 290) ha−1yr−1, respectively,compared to Rs. 1560 (US $ 28) ha−1yr−1) with the FS–FS system. Applying 120 kg of N ha−1considerablyincreased the profitability of all systems, lifting median gross profits of the sorghum + chickpea systemover Rs. 60,000 (US $ 1091) ha−1yr−1and the conventional system to Rs. 20,570 (US $ 374) ha−1yr−1. Thegross profit margin analysis showed that nitrogen is a key input for improving productivity, particularlyfor the double cropping systems. However, traditional systems are unviable and risky without N appli-cation in the variable climates of the semi-arid tropics. Together, our results show that on Vertisols insemi-arid India, double cropping systems increase systems’ productivity, and are financially more pro-fitability and less risky than traditional fallow post-rainy systems while further benefits can be achievedthrough fertilizer application.