Abstract
The intensive use of groundwater and nitrogen fertilizer has led to serious negative impacts on the environment of the North China Plain (NCP). Water footprint is an emerging approach to assess the consumptive water use and the environmental impacts on winter wheat-summer maize systems. A seven-year rotation experiment was conducted to collect data on wheat and maize growth response to nitrogen rates and irrigation schedules and to explore how the water footprint was affected, using DSSAT 4.6 Wheat and Maize crop models. Results showed that the increase in farm inputs contributed greatly to the increase in water footprint, primarily through the grey water footprint. The water footprints of maize and wheat were more sensitive to the nitrogen rate and irrigation, respectively. An irrigation of 160 mm produced a minimum total water footprint and higher yield for wheat. The grey water footprint of maize increased linearly when the nitrogen rate applied to maize exceeded 60 kg ha−1. Water-saving irrigation with 300 kg ha−1 of nitrogen can maintain a higher grain yield and have little impact on the environment. The approach used and the results can help to develop management strategies to maintain high yields while minimizing the water footprint in NCP.
Highlights
The winter wheat-summer maize double cropping system in the North China Plain (NCP) is one of the most intensive agricultural systems worldwide and this rotation is widely used in Asian countries [1,2]
The simulated yield of summer maize was a little lower than observations, the performance of the calibrated Decision Support System for Agrotechnology Transfer (DSSAT)-Maize model was considered as acceptable with a normalized nRSME < 10% and a d-index close to 1 across different nitrogen treatments under full irrigation. These results indicated that the model was able to accurately simulate the production of winter wheat and summer maize rotation response to different nitrogen treatments in North China Plain
We found that the water footprint of wheat increased with the increase of nitrogen rate, but the increments of total and grey water footprint of maize by increasing nitrogen fertilizer in maize were higher than those of wheat
Summary
The winter wheat-summer maize double cropping system in the North China Plain (NCP) is one of the most intensive agricultural systems worldwide and this rotation is widely used in Asian countries [1,2]. The North China Plain produces 56% of the wheat and 25% of the maize grain in China [3]. The water footprint is defined as the volume of freshwater used to produce a crop measured over the various steps of the production chain [10]. The water footprint has three components: consumption of surface and ground water (blue water), consumption of rainwater in crop production (green water), and the volume of freshwater that is required to assimilate the load of pollutants during the crop production process (grey water) [10]
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