Estimation of fixed nitrogen by field-grown green manuring legumes in Gasa, Bhutan

Project Leader:
Toshiyuki ISOI
Faculty of Agriculture

Bhutan envisions becoming gOrganich by 2020. Gasa has already been declared an gOrganic Dzongkhagh in 2008. Although nitrogen is the most important nutrient for crops, organic farming practices sometimes reveal nitrogen deficiency when the applied amount is not enough. Using green manures is a simple way to improve this situation. Since roots of leguminous plants are generally nodulated by infection of nitrogen fixing bacteria called rhizobia, leguminous green manures infected by these symbiotic bacteria fix atmospheric nitrogen in a form that plants can use. Therefore they can be alternatives to chemical nitrogen fertilizer. The ƒÂ15N method is a strong tool for fixed nitrogen estimation. We intend to try to estimate the amount of fixed nitrogen of green manures in the region in this research.

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