Strategic double cropping on Vertisols: A viable rainfed cropping option in the Indian SAT to increase productivity and reduce risk

Our 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

Efeito de práticas culturais na conversão e no balanço energéticos Effect of cultural practices on energy conversion and balance

Desenvolveu-se de 1997 a 2003, em Passo Fundo (RS), um experimento constituído de quatro sistemas de manejo de solo (plantio direto, cultivo mínimo, preparo convencional de solo com arado de discos e preparo convencional de solo com arado de aivecas) e de três sistemas de rotação de culturas: sistema I (trigo/soja); sistema II (trigo/soja e ervilhaca/milho ou sorgo) e sistema III (trigo/soja, ervilhaca/milho ou sorgo e aveia branca/soja). O delineamento experimental foi o de blocos ao acaso, com parcelas subdivididas e três repetições. A parcela principal foi constituída pelos sistemas de manejo de solo, e as subparcelas, pelos sistemas de rotação de culturas. Neste trabalho, apresentam-se a conversão energética (energia disponível/energia consumida) e o balanço energético (energia disponível - energia consumida) no período de 7 anos. No sistema plantio direto houve conversão e balanço energéticos (72,44 e 190.766 MJ ha-1) superiores ao cultivo mínimo (64,06 e 167.349 MJ ha-1), aos preparos convencionais de solo com arado de discos (54,35 e 134.982 MJ ha-1) e com arado de aivecas (52,02 e 128.159 MJ ha-1) respectivamente. O trigo em rotação de culturas foi mais eficiente energeticamente do que a monocultura desse cereal. Na cultura de milho foi observada maior eficiência energética.<br>The effects of soil management systems and crop rotations were assessed from 1997 to 2003, in Passo Fundo, Rio Grande do Sul State, Brazil. Four soil management systems (no-tillage, minimum tillage, conventional tillage using disk plow, and conventional tillage using moldboard plow) and three crop rotation systems [system I (wheat/soybean), system II (wheat/soybean and common vetch/corn or sorghum), and system III (wheat/soybean, common vetch/corn or sorghum and white oats/soybean)] were compared. An experimental design of blocks at random with split-plots and three replications was used. The main plot consisted of soil management systems, while the split-plots consisted of crop rotation systems. Energy conversion (energy available/energy consumed) and balance (energy available - energy consumed) during a seven-year period is presented in this paper. No-tillage showed higher energy conversion and balance (72.44 and 190,766 MJ ha-1) than minimum tillage (64.06 and 167,349 MJ ha-1), conventional tillage using disk plow (54.35 and 134,982 MJ ha-1), and conventional tillage using moldboard (52.02 and 128,159 MJ ha-1), respectively. Wheat within crop rotations presented higher energy efficiency in energy than the monoculture of this cereal. The corn crop was observed the highest energy efficiency of this study