The potential of fertilizer management for reducing nitrous oxide emissions in the cleaner production of bamboo in China

Quantifying the rapidly increasing nitrous oxide emission from excessive nitrogen fertilizer input is a pressing demand for reducing greenhouse gas in cleaner agricultural production. The purpose of this work is to assess the nitrous oxide emission from the intensively fertilized bamboo plantations to better understand the mitigation potential of fertilizer management, and to develop an approach for advancing the site-specific emission factors considering influences of climate and soil conditions. Based on the commonly adopted fertilization practices, the biogeochemical model DeNitrification-DeComposition was adjusted and validated to estimate and analyze nitrous oxide emission under four typical fertilizer management scenarios, namely fertilizer input reduction, split fertilization, deeper placement, and slowrelease fertilizers. The simulation results show that the tested fertilizer management practices present great potential for reducing nitrous oxide emissions whereas mitigation effect of each adaptation depends on the site-specific conditions. In the cases of China, fertilizer reduction and adaptation with slowrelease fertilizers application are shown to be the most cost-beneficial fertilization options for nitrous oxide mitigation in humid and arid regions, respectively. The highest mitigation achievable ranged from 60.3% (humid coast) to 92.9% (arid inland) compared to the current practice with excessive fertilization. If these adapted fertilization practices are implemented at the national scale, approximately 8.02 -11.38 million tonnes carbon dioxide equivalents per year of nitrous oxide emission could be reduced in 2030, which is 4.0%-5.7% of the total nitrous oxide emission from China's upland cropping system. The results indicate the critical importance of site-specific fertilizer management on reducing nitrous oxide emission in bamboo production. By considering the site-specific conditions, the overall biogeochemical modelling approach could serve as a more effective tool than the commonly used emission factors to quantify emission and screen fertilizer management options in cleaner agricultural production.