Potentials of green manure in integrated nutrient management for rice – A review

The agriculture of the modern chemical era concentrates on maximum output but overlooks input efficiency as a result of which it has not been sustainable. Stagnation in maximum yield potential during the recent years in crops like rice and wheat is a real concern for agricultural scientists and professional technocrats. Undoubtedly the decreasing rate of increase in cereal production is mainly attributed to too much dependence on inorganic fertilizers mainly high analysis fertilizers. Under high input production systems where productivity cannot be further increased with incremental useof mineral fertilizers alone, addition of organic sources could increase yields through increased soil productivity and higher fertilizer use efficiency. Green manuring of rice is awell established practice and saving of fertilizer N through green manuring ranged from 30 to 100 kg N ha⁻¹. The magnitude of leaching, denitrification and NH₃ volatilization losses are lower for green manure-N than for fertilizer-N. In addition, green manures provide N and other mineral nutrients for the immediate need of the growing rice crop and improve soil physical and chemical properties. There was considerable build up of soil organic carbon content due to the addition of organic N sources especially green manures. Combined application of fertilizer and green manure increased the efficiency of each other. The past research on these aspects would enable scientists working on green manures and hence reviewed here under.