Maintaining of High Crop Yield and Reduction of Greenhouse Gas Emission Can be Achieved By Optimized Fertilization in North China Plain.

A large number of field experiments have been conducted to reduce Greenhouse Gas (GHG) emission by diverse farming measure, although these studies are mostly for short term periods (1-2 years). In many developing countries like China, it is more a challenge if high crop yield is to be achieved during the process of exploring farming techniques of reducing GHG emission. We implemented a field experiment with optimized nitrogen (N) fertilization management (OPT, 1/3 lower of N than conventional practice, FP) since 2008 and monitored the GHG from the typical winter wheat-summer maize cropping system in North China Plain. We found that annual N₂O emissions from OPT (3.1±0.2 N₂O-N kg ha^-1 yr^-1) were significantly lower than FP (4.8±0.8 N₂O-N kg ha^-1 yr^-1) after the 4^th year of the experiment. Nitrogen utilization efficiency (NUE) of OPT was significantly higher than FP in wheat season (44% vs. 32.2%) while in maize season, the difference in NUE was not significant. Mineral N in the soil was also significantly lower in OPT than in FP (P<0.05), reducing the risk of contaminating water bodies. There was no significant difference on crop yield between OPT and FP treatments. Our results suggests that optimized N management (up to 1/3 of N reduction) can achieve the dual goal of maintaining high crop yield while reducing the GHG emission in the intensified farming region of North China.