Enhancing sustainability and productivity in upland rice-okra-green manure cropping systems through conservation agriculture practices

Conservation agriculture (CA) is a sustainable farming approach aimed at enhancing agricultural productivity while minimizing environmental impact. It is based on three core principles: minimal soil disturbance, permanent soil cover, and diversified crop rotations. This study explores the application of CA practices in upland rice-based cropping systems to improve productivity and sustainability. A field experiment was conducted from 2019 to 2021 at Kerala Agricultural University's Agronomy Farm to evaluate environmentally friendly conservation measures for upland rice-based cropping systems. The study compared a rice-okra-green manure cropping system under conservation practices with conventional methods, employing ten treatments with three replications. The first rice crop was established using two planting methods—flatbed and raised bed—in combination with either green manuring or brown manuring. Following rice cultivation, okra was grown with minimal soil disturbance, and cowpea was introduced as a green manure crop in the third phase over two years. Pooled results from the two-year experiment indicated that direct-seeded rice in a flatbed with green manuring achieved the highest grain yield (2.71 t/ha), crop water use efficiency (10.77 kg/ha-mm), field water use efficiency (1.33 kg/ha-mm), relative economic efficiency (11.08), and partial factor productivity for nitrogen (92.35 kg/ha), phosphorus (87.07 kg/ha), and potassium (87.07 kg/ha). The conservation agriculture practices applied to the preceding rice and okra crops significantly influenced the growth, yield attributes, and productivity of okra within the rice-okra-green manure cropping system. Okra grown on a flatbed with crop residue mulching outperformed other treatments, yielding a maximum productivity of 16.47 t/ha under the direct-seeded rice in a flatbed with green manuring, followed by okra with crop residue mulch. Resource use efficiency parameters, including crop water use efficiency and partial factor productivity, were highest under direct-seeded rice in a flatbed with green manuring, followed by okra with crop residue mulch. These results were statistically on par with direct-seeded rice in a flatbed with brown manuring, followed by okra with crop residue mulch. The highest benefit-cost ratio for the entire cropping system was observed in the sequence of direct-seeded rice in a flatbed with green manuring, followed by okra with crop residue mulch and cowpea as green manure. Overall, the study concluded that adopting a system-based approach with direct-seeded rice in a flatbed with green manuring, followed by okra with crop residue mulch and cowpea as green manure, is a cost-effective, environmentally sustainable, and resource-efficient conservation agriculture practice for upland farming. This approach enhances yield, profitability, and resource use efficiency, making it a viable strategy for sustainable upland agriculture.