A simulation model assisted study on water and nitrogen dynamics and their effects on crop performance in the wheat-maize system: (II) model calibration, evaluation and simulated experimentation

Abstract

The test on the model with data collected from two years’ field experiments revealed an ability to satisfactorily simulate crop parameters such as LAI, biomass accumulation and partitioning, yield, and variables influencing crop growth and development as nitrogen uptake by crops and partitioning in different organs, and dynamics of soil water and nitrogen including infiltration and leaching. With the model, crop yield, water use efficiency (WUE), nitrogen use efficiency (NYE) and water-nitrogen leaching at specific soil layers under various water and nitrogen management practices were simulated to provide data used as references for designing sustainable nitrogen and water management practices.

The outputs of the simulated experiment with various treatments of irrigation and nitrogen application indicated that crop yield was closely related to water and nitrogen application, crop water use was positively related to irrigation amount, and nitrogen fertilization could improve the crop water use and WUE within certain limits. This is a valuable evidence to be considered in water-saving farming. Nitrogen uptake had a positive relation to nitrogen application, while irrigation to some extent improved its uptake by crops and hence increased NYE. Additionally, irrigation and fertilization had great effects on nitrogen leaching. Thus, in order to improve WUE and NYE, the model showed how nitrogen application and irrigation should be well coordinated.

Key words： wheat; maize; cropping system; water; nitrogen; simulation; model

Acknowledgements

The authors wish to give their sincere thanks to Dr. Ren Tusheng of China Agricultural University for his important assistance by providing his up-to-date knowledge and experiences in soil physics and laboratory work. He has been also very helpful in giving constructive suggestions in model building. Thanks also give to Professor Hu Chunsheng of Chinese Academy of Sciences in Shijiazhuang for providing kind help with the field experiment and data analysis.

Professors Li Yanming, Cui Yanhong and Zhang Jianping at Agricultural University of Hebei have given much advice on biology and management of wheat and maize. Mr. Zhao Yingmu, Miss Xie Zhixiao and Miss Shi Xiupeng in Xinji County of Hebei Province dedicated their time and efforts in managing the experimental fields and providing facilities and other assistance for accomplishing the experiment. Mr. Chen Jianwei, Miss Zhao Xiaoyan and some students from Zhangjiakou Agricultural College also assisted in field management, taking samples and processing data. The authors thank them all for the great assistance.

This study is a part of the key program of the China National Scientific Technical Support for the 11th Five-Year Plan ‘The study and demonstration of technology integration on the double cropping system of wheat and maize in the central and northern three-H Plain (Hebei)’ (No. 2006BAD02A08).

This research has also been financed by the International Collaboration Funds of the Ministry of Science and Technology of China.

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