Journal of Scientific Research and Reports

A field experiment was conducted during the kharif seasons of 2018–19 and 2019–20 on the clay loam soils of the Agricultural Research Station, Jangamaheswarapuram, Andhra Pradesh. The objective of the experiment was to determine the optimum sowing window for seed production in three important green manure crops, viz., Sunnhemp (Crotalaria juncea L.), Dhaincha (Sesbania aculeata), and Pillipesara (Vigna trilobata). The experiment was laid out in a split-plot design with three crops as main plots and four sowing windows (first FN of August, second FN of August, first FN of September, and second FN of September) as subplots. Among the crops, Sunnhemp recorded the highest seed yield during both years (1,134 kg ha⁻¹ in 2018 and 918 kg ha⁻¹ in 2019), significantly outperforming Dhaincha (736 kg ha⁻¹ in 2018 and 664 kg ha⁻¹ in 2019) and Pillipesara (645 kg ha⁻¹ in 2018 and 456 kg ha⁻¹ in 2019) owing to its superior biomass production and efficient source-sink partitioning. Sowing during the first FN of August proved to be the optimum window, producing the highest seed yields of 1,037 kg ha⁻¹ in 2018 and 832 kg ha⁻¹ in 2019. Economic analysis indicated that Sunnhemp generated the highest net returns among the crops (Rs. 47,142 ha⁻¹ in 2018 and Rs. 37,694 ha⁻¹ in 2019). Regarding sowing dates, early sowing in the first FN of August recorded the highest net returns (Rs. 49,537 ha⁻¹ in 2018 and Rs. 37,007 ha⁻¹ in 2019) with the maximum return per rupee invested (1.86 in 2018 and 1.46 in 2019). The findings demonstrate that sowing Sunnhemp during the first fortnight of August is the most productive and economically viable strategy for sustainable green manure seed production in the NSP command area, thereby ensuring greater availability of quality seed for green manuring programmes.