PJB-2018-477
SIMULATION OF SOIL WATER CHANGING AND RYEGRASS GROWTH IN THE HILLY REGIONS BASED ON THE EPIC MODEL
WENPING ZHOU
Abstract
To clarify the dynamic changing of soil water has great meaning for the improvement of water management in ryegrass land, to evaluate EPIC model is better to improve and accurate the EPIC model for ryegrass land, also it will promote the application of cropping system simulation and decision making technology in forage-grain cropping system. By field experimental and simulating method, this paper researched the growth process of ryegrass and dynamic changing of soil water in ryegrass land and clarified the accuracy of EPIC (Environmental Policy Integrated Climate) model to simulate ryegrass growth and soil water changing. Results showed 1). Though available soil water was relative lower during March to May, it recovered better during May to October in deep soil (0.4-0.6 m). Reasonable increase fertilizer for ryegrass land was better to increase forage yield and leaf area index at the hilly region of Sichuan Province. 2) Correlation index between observed and simulated available soil water in 0-1 m soil was 0.86-0.95, with the RRMSE value of 6.0%-17.2%; correlation index between observed and simulated soil water distribution in 0-1m soil was 0.57-0.92; most of them was higher than 0.85. 3) Correlation index between simulated and observed value of forage yield, leaf area index and height of ryegrass were all higher than 0.90, there is not significant difference between simulated and observed value for forage yield, leaf area index and height of ryegrass. The EPIC model can simulate soil water and forage yield of ryegrass land well, it can be used as a better tool to evaluate and research the suitableness of grain-forage cropping system at the hilly regions of Sichuan Province
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