Increased N fertilizer input enhances CH4 and N2O emissions from soil amended with low amount of milk vetch residues
The combined use of chemical N fertilizer and crop residue could influence greenhouse gas emissions in agriculture. A pot experiment was performed to examine the combination of milk vetch residue and chemical N fertilizer and the amount of total N input on CO2, CH4 and N2O emissions from paddy soils. Neither fertilizer combination nor fertilizer amount influenced cumulative CO2 emissions. Cumulative CH4 emissions increased with increasing proportion of milk vetch residues. Nevertheless, with low milk vetch residue application rate, increased chemical N fertilizer input significantly enhanced CH4 emissions. Cumulative N2O emissions from soils amended with low and moderate amount of milk vetch residues were promoted by increased N fertilizer input. By contrast, N2O emissions from soils without milk vetch residue application or amended with high milk vetch residues were not influenced by increment of N fertilizer. It was concluded that both CH4 and N2O emissions were promoted by increased N fertilizer, which might be due to the microbial activity and N immobilization in soils amended with different amounts of milk vetch residues.
KeywordsGreen manure Mineral N fertilizer GHG Methane Carbon dioxide Nitrous oxide
This research was supported by the earmarked fund for China Agriculture Research System (CARS-34), the Fundamental Research Funds for the Central Universities (KYZ201756) and the Natural Science Foundation of Jiangsu Province (BK20171378).