Low Cost Zero till In situ Green Manuring for Kharif Rice-A Success Story

Abstract

Low cost zero till in situ green manuring using plant species like dhaincha (Sesbania aculeata) and sunnhemp (Crotalaria juncea) will eliminate the age old problems of large scale adoption of green manuring across the farming community. These two species germinated and grown well when sown before (as paira crop during last irrigation) or after rice harvest under zero till condition, with assured nor western rain/monsoon rain or with one post sowing irrigation (7.5 cm). The zero till paira dhaincha green manuring process opened up the scope of producing green manuring at lower cost and saves up to Rs.15000/ha over conventional rain fed green manuring system. Green manuring by dhaincha produced 50-60 tonnes of biomass at 35-40 DAS in alluvial (North 24 PGS),  lateritic (Purulia)  and clay soils (Paschim Medinipur), produced 30-50 q raw rice /ha and saved 20-27 kg (30 per cent) chemical nitrogen/ha. This green manure will help in quicker decomposition of rice straw left after combined harvest (3.5- 6,0 t/ha), minimise its field burning, sequester enough carbon to the soil. Fifty tonnes green biomass of dhaincha/sunnhemp, has the potential to absorb 15 tonnes CO2 from the atmosphere, sequesters 2 tonnes of carbon in soil, minimise environmental pollution, improve soil health, its structure and water holding capacity. This technique can be adopted in rice growing countries across the globe without difficulty.  Seed production dhaincha and sunnhemp  is possible by growing it as paira crop (40 kg/ha) within kharif rice which grows up to 45 cm height, produces healthy pods and matures by 70 days which otherwise takes 5-8 months in normal season. If the seed crop is not harvested in rice fallows, from shattered seeds, self-seeded zero till and rain fed dhaincha manure can be obtained in rice fallows.