Sustaining Castor Productivity by Relative Use of Green Manures and Nitrogen Levels

In an experiment conducted at the Agricultural College Farm, Raichur on deep black clay soil during late Kharif season of 2002-03 on sustaining castor productivity by relative use of green manure and nitrogen levels. The results showed that, green leaf manuring of sunnhemp recorded significantly higher seed yield (10.23 q ha^-1), seed weight per plant (62.78 g), number of spikes per plant (8.46), dry matter accumulation in reproductive parts (40.70 g plant^-1), dry matter accumulation in stem (87.19 g Plant^-1) and leaf area (85.82 dm^-2 plant^-1) over the sole castor without green manuring and castor with in situ green manuring. Among the nitrogen levels, application of 80 kg N ha^-1 produced significantly higher seed yield (10.09 q ha^-1), seed weight per plant (59.20 g), number of spikes per plant (7.93), dry matter accumulation in reproductive parts (38.82 g plant^-1), dry matter accumulation in stem (83.91 g plant^-1) and leaf area (90.58 dm^-2 plant^-1) over the control, application of 20 kg N ha^-1 and 40 kg N ha^-1. However, it remained at par with the application of 60 kg N ha–1 (10.07 q ha^-1, 58.57 g plant^-1, 7.73, 38.51 g plant^-1, 83.57 g plant^-1 and 90.26 dm^-2 plant^-1 of seed yield, seed weight per plant, number of spikes per plant, dry matter accumulation in reproductive parts, dry mater accumulation in stem and leaf area, respectively).