Improved water management practices improve cropping system profitability and smallholder farmers’ incomes

In the Eastern Gangetic Plain of South Asia, cropping systems under conventional crop management are frequently unprofitable due to the inefficient use of resources, particularly irrigation water and energy. Across the Eastern Gangetic Plain, farmers generally produce a wet-season rice crop followed by an irrigated dry season crop: maize has been recently introduced as the dry-season crop and is rapidly growing in popularity. Irrigation water is commonly applied using diesel-powered pumps and fluctuating fuel prices are a major factor affecting cropping system profitability. We hypothesised that the adoption of zero tillage crop establishment in a rice-maize system would reduce irrigation requirements compared to a conventionally-established rice-maize system, while maintaining comparable crop yields. Thus, higher water use efficiency and economic profitability would be achieved under the improved crop management compared to conventional practice. Field experiments over two years in Sabour, Bihar, demonstrated that early sowing of maize resulted in 8% higher maize grain yields, while zero tillage establishment produced 7% higher maize grain yields than conventionally established maize. Using the APSIM cropping systems model we tested our hypothesis over 49 years, from 1969 to 2018. Over the longer-term, zero-till maize grain yields were 9% higher than those of conventionally established crops. Under these improved management practices fuel savings of 8–15 % and labor savings of 34–43 % were achieved compared to conventionally managed crops, leading to higher water use efficiency in all treatments under improved management. Overall, gross margins in rice-maize systems under improved management practices were 20–39 % higher than rice-maize systems under conventional management. In rice-maize cropping systems in the Eastern Gangetic Plain, improved crop management practices can improve the efficiency of water use and thus increase farming households’ profitability and incomes.