Relay sown dhaincha (Sesbania) before combine harvested summer rice,for green manuring, WB, 2024

Low Cost Zero Tillage in situ Green Manuring for Kharif Rice-a Success Story
Dr.Ankit Kumar Ghorai and Dr. Asesh Kumar Ghorai
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 in the globe. These two species germinated and grown well when sown before (as paira /relay 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, add 11 tonnes of oxyg, sequesters 2 tonnes of carbon in soil, minimise environmental pollution, improve soil health, its structure and water holding capacity. 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. This technique can be adopted in rice growing countries across the globe without difficulty. Kharif rice yield varied from 3.5 to 5 t/ha under different varieties and locations. It reduced weed population in rice field by 60-70 percent in different locations.
N.B: This year (2024) young and tiny dhaincha seedlings survived acute drought stress with no rainfall for 30 days and consistent high temperatures ranging from 40-45 degree Celsius over ten days with hot loo, in clay soil. In loam soil 50 percent dhaincha seedlings scrotched out and thus seed rate should be doubled to 60 kg/ha over 30 kg /ha to get proper plant population under prolonged drought with high temperatures.
References:
1.Ghorai A.K., Ghorai, Ankit Kumar and Kalyan Jana [2022].Low cost zero till in situ green manuring for faster decomposition of left over rice/wheat stubbles from combined harvest to minimse field burning : an opinion. Asian Journal of Agricultural Extension, Economics & Sociology. 40 (9): 161-166, 2022.
2. Ankit Kumar Ghorai and Asesh Kumar Ghorai (2023). International Journal of Environment and Climate Change. 13(7): 317-323.
Address:
1.Dr. Asesh Kumar Ghorai, Retired scientist (Agronomy), ICAR -CRIJAF, New Delhi, India. E-mail: [e-mail]
2.Dr. Ankit Kumar Ghorai. Assistant Director of Agriculture, Department of Agriculture, WBAS, Baghmundi, Purulia, W.B., India.