ABSTRACT
It has been a principal problem for India to supply food to support its increasing population. Increasing nitrogen fertilizer input has contributed to solving this problem by raising crop yields. On the other hand, nitrogen is a factor causing various types of environmental pollution. For example, groundwater pollution, the eutrophication of rivers and wetlands, and outbreaks of red tide are becoming severe problems. Fertilizer subsidy, which has helped farmers to get fertilizers at low rice, has played an important role to increase fertilizer input. However, because the subsidy burden of the government has been increasing, a reform of the subsidy system is required. This study aims to clarify the influence of fertilizer subsidy to the nitrogen cycle in India by analyzing the transition of the fertilizer subsidy system and the change of the nitrogen cycle. Analysis of the nitrogen cycle reveals that nitrogen efficiency in the whole of India largely deteriorated from 2000 to 2010. In order to prevent environmental pollution caused by nitrogen fertilizer use, improvement of nitrogen efficiency is required. Analysis of the transition of the fertilizer subsidy system and cereal production shows that nitrogen fertilizer is the most important fertilizer to increase cereal production compared with phosphate fertilizer and potassium fertilizer. In addition, an impact of a future change of the fertilizer subsidy system to the nitrogen cycle and cereal production in India is also examined.
