Economic analysis of conservation agriculture in maize-based farming systems in Nepal

A linear programming technique was used to estimate the revenue maximizing allocation of land for a representative household using conservation agriculture production system (CAPS) and farmers’ traditional practices. Four practices with conventional tillage taken for model were maize followed by millet i.e. CT[M-Mi], black gram i.e. CT[M-Bg], cowpea i.e. CT[M-C] and followed by millet+cowpea intercrop i.e. CT[M-Mi+C]. One strip tillage practice included in model was maize followed by millet+cowpea intercrop i.e. ST[M-Mi+C]. The model was optimized in five different scenarios. Scenario 1, 2, 3 and 4 were build by allowing annual soil loss to 1, 2, 3 and 4t ha-1yr-1 respectively, whereas scenario 5 was build with unconstrained soil loss. The results of scenario 1 suggest that unless soil loss is considered, conservation tillage does not appear in the profit maximizing allocation of land. Practice with strip tillage appeared in the profit-optimized model of all scenarios where soil loss was constrained in base year. Scenario 1 and 2 had about 71 and 66 % of cultivated land covered with ST [M-Mi+C] practice. But, CT [M-Bg] covered about 65% of the land under soil loss unconstrained model. Result also suggested that the representative farm have to sacrifice about $88.6 ha-1yr-1 for about 7 years (-7.6% revenue) if they aim to reduce the soil loss to 1 t ha-1 yr-1, $50.1 ha-1yr-1 for about 6 years (-4.2% revenue) if they target to reduce soil loss to 2 t ha-1yr-1, and about 27.13 (-2.3% revenue) t ha-1yr-1 to target soil loss of 3 t ha-1yr-1. An analysis of the total change in economic surplus associated with adopting the revenue maximizing crop mix was completed. The analysis suggests that conservation agriculture will eventually pay off because total change in economic surplus for 12 years is estimated to be $3,735 million (net present value) if only 1% of the total area adopts the revenue maximization crop mix with a 2 t ha-1yr-1 soil loss constraint.