Simulation on regulation for efficient utilization of water and fertilizer resources in paddy fields

Water and fertilizer are main factors influencing crop yield and ecological environment. In order to explore the law of water and fertilizer in the paddy field, reach the target of minimizing irrigation water, fertilization and drainage water as well as maximizing the rice yield, the response relationship on the amount of drainage water and the yield under different conditions of rainfall frequency, irrigation methods, fertilization level, controlled drainage were analyzed based on the observation data of experiment on water and fertilizer coupling irrigation and controlled drainage in Tuanlin, Zhanghe Irrigation District, Hubei province, and the combination of crop growth model ORYZA2000 and DRAINMOD 6.0 model. The nitrogen production function was obtained through calculation and analysis. The paper proposed the threshold of amount of water and fertilizer where agriculture management of intermittent irrigation is applied. The study results indicated that when the irrigation water capacity was 30 mm, the application of nitrogen was 170 kg/hm2, and the water table of controlled drainage was 20 cm, water conservation was reached to 12.5%–18.87%, fertilizer application was reduced by 35.1%, yield increased by 11%, the amount of discharge water was reduced by 19.9%. Therefore, the study can help to strengthen the scientific management of water and fertilizer, promote the use efficiency of water and nitrogen, and prevent agricultural non-point source pollution. It is also important to promote the sustainable development of irrigation district.