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Title: Quantifying climate and management effects on regional crop yield and N leaching in the North China Plain

Author
item FANG, Q - Qingdao Agricultural University
item Ma, Liwang
item YU, Q - Chinese Academy Of Sciences
item HU, C - Chinese Academy Of Sciences
item LI, X - Chinese Academy Of Sciences
item Malone, Robert - Rob
item Ahuja, Lajpat

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2013
Publication Date: 9/1/2013
Citation: Fang, Q.X., Ma, L., Yu, Q., Hu, C.S., Li, X.X., Malone, R.W., Ahuja, L.R. 2013. Quantifying climate and management effects on regional crop yield and N leaching in the North China Plain. Journal of Environmental Quality. 42:1466–1479.

Interpretive Summary: Correct management of soil water and nitrogen (N) is critical for maintaining agricultural productivity and preserving groundwater resources. In this study, the calibrated agricultural system model, the Root Zone Water Quality Model (RZWQM2), was used to assess water and N use by crops, N leaching and crop yield for long-term (1970-2009) conventional irrigated, double-cropped wheat-maize management systems across 15 locations in the North China Plain. N application rate was the dominant factor for the spatial variability of N leaching in both wheat and maize seasons across these locations. The long-term wheat yield was highly correlated to total water input (seasonal rainfall plus irrigation), and the long-term maize yield showed significant correlations with N application rates. Seasonal rainfall explained 48%-80% of the temporal variability in N leaching in the maize seasons across locations, while in the wheat seasons, significant correlations between seasonal N leaching and rainfall were found only at 5 locations. Seasonal rainfall explained more variations in wheat yield than in maize yield across these years at the 15 locations. N leaching generally is more responsive to N application rate than to irrigation, while the reverse was true for crop yield at most locations. Based on the long-term simulation results and water resources availability in the region, 40-60% of the conventional N application rate and 60-80% conventional irrigation amount were recommended for these locations.

Technical Abstract: Water and nitrogen (N) are the most important management inputs for increasing agricultural production, but are also contributing to the depletion and nitrate-N pollutions of the groundwater resources in China and other countries. In this study, the calibrated agricultural system model, the Root Zone Water Quality Model (RZWQM2), was used to assess water and N use by crops, N leaching and crop yield for long-term (1970-2009) conventional irrigated, double-cropped wheat-maize management systems across 15 locations in the North China Plain. N application rate was the dominant factor for the spatial variability of N leaching in both wheat and maize seasons across these locations. The long-term wheat yield was highly correlated to total water input (seasonal rainfall plus irrigation), and the long-term maize yield showed significant correlations with N application rates. Seasonal rainfall explained 48%-80% of the temporal variability in N leaching in the maize seasons across locations, while in the wheat seasons, significant correlations between seasonal N leaching and rainfall were found only at 5 locations. Seasonal rainfall explained more variations in wheat yield than in maize yield across these years at the 15 locations. N leaching generally is more responsive to N application rate than to irrigation, while the reverse was true for crop yield at most locations. Based on the long-term simulation results and water resources availability in the region, 40-60% of the conventional N application rate and 60-80% conventional irrigation amount were recommended for these locations.