Economic analysis of conventional and conservation bench terrace systems in a sub-humid climate

Water scarcity, accelerated soil erosion, and food security are the basic concerns in rain-dependent agricultural systems. The conservation bench terrace (CBT) system, in conjunction with water harvesting and recycling techniques, is an efficient conservation measure for in situ rain water harvesting, minimizing soil erosion, and sustaining productivity in arid, semi-arid, and sub-humid climates. Economic analysis has revealed that the CBT system exhibited 71.7% and 58.5% higher net present value (NPV), respectively, when compared to a rainfed maize-wheat system and a conventional system of sloping borders (i.e., making plots on slopes at 2% to 4%) with supplemental irrigation from harvested runoff. Various combinations of conventional and CBT systems were analyzed for economic efficiency, nutrient loss, and food security under different probabilities of runoff-producing rainfall by extrapolating the experimental data. The pure CBT system was found to be inadequate to generate sufficient runoff to provide even one pre-sowing irrigation of 5 cm depth to winter wheat crop. In contrast, pure conventional and a combination of conventional and CBT systems in the ratios of 50:50 and 75:25 had the potential to yield runoff more than sufficient to provide two supplemental irrigations to wheat crop at all probability levels. However, these systems result in higher soil and nutrient losses. The conventional and CBT systems in the ratio of 25:75 produced sufficient runoff to provide two irrigations with negligible overflow. Benefit cost ratio (BCR), payback period (PBP), and internal rate of return (IRR) criteria favor the pure CBT system owing to its low initial investment on pond construction for less runoff storage. However, NPV was always superior for combinations of conventional and CBT systems in the ratios of 25:75 or 50:50 over other combinations. Total maize-equivalent and energy production criteria also confirm that these two combinations perform better than the others. It is thus concluded that conventional and CBT systems in the ratios of 50:50 or 25:75 are the best choices to maximize economic returns, ensure food security, minimize soil and nutrient losses, and produce sufficient runoff for harvesting and recycling under rainfed cropping systems in sub-humid climates.