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

•Productivity of double crop systems was greater than fallow post-rainy systems, a better choice to risk-averse farmers.•Double cropping increased systems’ N uptake due to cropping in the rainy season instead of fallowing.•Legumes in the improved cropping systems contributed residual N to sorghum and enhance sorghum yields in these systems.•Gross profits analysis of cropping systems indicates N is the key for improving productivity.•Traditional fallow systems on Vertisols are economically risky without N application to the crops.