Bioeconomic optimization of conservation agriculture production systems (CAPS) for smallholder tribal farmers in the hill region of Nepal

Abstract

This research was conducted to determine the potential for the use of Conservation Agriculture Production Systems (CAPS) in the hill region of Nepal, an area highly prone to food insecurity and soil losses. Conservation agriculture (CA) includes the practices of tillage reduction, soil cover maintenance, and optimal crop rotation. Farming in Nepal consists of two main cropping seasons: rainy and postrainy. Therefore, the annual production system includes different CA practices suitable for each cropping season. Due to conflicting criteria for maximizing farm profits while minimizing soil losses from CA, this study used a dynamic multiobjective linear programming model with a 20-year horizon to predict the optimal solution. Seven systems combining varying tillage practices (full versus strip tillage), cropping patterns (sole versus intercropping), and four crops were used for analysis. The results showed the optimal CAPS as strip tillage of maize (Zea mays L.) followed by intercropping millet (Eleusine coracana) and legumes; however, there are some variations in net present value (NPV) of profits due to the length of the planning horizon and discount rates. For long planning horizons of 20 years, farmers' objectives would be optimized when all land is allocated to strip tillage systems by year 2. The results show that the economic gains from practicing strip tillage–based CA varies among villages, ranging from 29% to 110% using discount rates of 10% and 48% to 274% under lower/social discount rate of 3%. In addition to profit, adoption of a CA system reduces the amount of soil loss by 83% to 88% over 20 years. Despite long-term benefits from CA, the short-term differences in the economic returns from CAPS are not enough for farmers to abandon their traditional practices. Therefore, from a societal welfare standpoint, it is recommended that the government provide short-term financial support to pay for the environmental services provided by the CAPS, and that CAPS education and training be made available to farmers. Additionally, long-term research to develop locally adapted CA practices may be necessary to fully realize the benefits for smallholder farmers.