Tillage and residue-management effects on productivity, profitability and soil properties in a rice-maize-mungbean system in the Eastern Gangetic Plains

Farmers' conventional tillage (CT) and residue removal practices in rice (Oryza sativa L.)-maize (Zea mays L.) systems in South Asia's Eastern Gangetic Plains (EGP) are input-intensive, costly, and soil degradative. We conducted a rice-maize-mungbean (Vigna radiata (L.) Wilczek) (R-M-MB) system experiment with six tillage and three residue-management treatments in Bangladesh, representing the EGP. Maize yields were significantly (p <= 0.05) higher under permanent (PB) and fresh (FB) beds under strip tillage (ST) than under CT, but there were no differences in mungbean yield. Rice yields under PB, FB, and CT were similar but significantly higher than those under zero or minimum tillage and ST. Yields of all crops increased significantly (p <= 0.05) with residue retention compared with no residue retention. Total system productivity was highest under PB, followed by FB and ST. Compared with CT, gross margins under PB, FB, and ST increased, respectively, by 18%, 13% and 11%, and soil organic matter (SOM) and total soil N content across tillage treatments increased by 11-16% and 12-24%, respectively. After 3 years, SOM, total N, and available P and S contents increased significantly (p <= 0.05) under residue retention. Results demonstrate the potential of PB, FB, and ST with residue retention in improving the productivity, profitability and soil health in the R-M-MB system of Bangladesh and on similar soils and climates in the EGP.