Evaluation of green manure technology in tropical lowland rice systems

Green manure (GM) is not superior to organic fertilizer in terms of agronomic efficiency. Use of GM destabilizes rice yield, and has higher unit production cost than N fertilizers. It produces higher cereal yields in farmers' field, but gives negative or trivial returns in the short-term conditions. When compared with grain legumes (GL) grown under similar conditions, GM is not economical both in the short- and long-term conditions. Integrating GL in the existing cropping system without disturbing the main crops in the system appears to have a greater chance of adoption, and may also provide long-term economic benefits to low-land rice-based systems. The economic feasibility of GM can be improved by enhancing its use as food and feed, which will improve its short-term advantage. The lesson for developing technologies in future is that they should have economic benefits in the short-term, otherwise these will be rejected by farmers, despite their long-term advantages. (C) 1999 Elsevier Science B.V. All rights reserved.