Status of mineral nitrogen fertilization and net mitigation potential of the state fertilization recommendation in Chinese cropland

Abstract

The overuse of mineral nitrogen (N) fertilizer is widespread and affects greenhouse gas (GHG) emission in China. In 2013, the Ministry of Agriculture released the ‘Recommendation for soil nutrient analysis-based mineral fertilizer application for corn, wheat and rice’ (hereafter the Recommendation). The aims of this study were to estimate current mineral N fertilization and net mitigation potential (NMP) for the Recommendation in the three main crops in China. To estimate the NMP from the Recommendation concerning the fertilizer recommendation (FR) scenario, we designed a current situation (CS) scenario by conducting a field questionnaire survey across typical cropping regions in China. Our results indicate that annual N fertilization amount was 19.1±1.2 (95% confidence interval) Mt N applied to the 66Mha of Chinese cropland in the CS scenario and would decrease by about 7.1Mt N in the FR scenario. This decrease might mitigate 37.4±5.2% of GHG emissions including carbon dioxide (CO2) from production and transport of N fertilizer, and nitrous oxide from soil due to N fertilization. Carbon (C) sequestration was 11.1±0.71TgCyr−1 under both scenarios. The NMP was 23.9±3.4TgCeqyr−1 in the FR scenario and might offset 1.1±0.16% of CO2 emissions from fossil fuel combustion in 2011 in China. In conclusion, implementation of the Recommendation could be a sustainable and cost-effective N management system to mitigate GHG emissions in Chinese cropland.