Evaluation of the Farmland Ecosystem Service Function of Spring Maize-Green Manure in the Northwest Irrigated Agricultural Area

Planting green manure in farmland is one of the important measures to improve the quality of cultivated land in Hexi irrigation district in Northwest China. This paper selects the main green manure varieties: vicia villosa roth and needle leaf pea in the Hexi irrigation district, and builds a spring maize-green manure farmland ecosystem service function value evaluation method, from the five service functions of agricultural product supply, soil nutrient accumulation, water conservation, soil conservation and gas regulation, to determine the ecological value of spring maize intercropping with different green manure farmland systems. Result shows that among the service function value of the spring maize intercropping green manure farmland ecosystem, the supply value of agricultural products and the gas regulation value have a greater contribution rate to the total value, ranging from 39% to 54% and 30% to 39%, respectively. Compared with single-cropping spring maize, the ecological value of spring maize intercropping vicia villosa roth and needle leaf pea farmland system increased by 19.37% and 43.74%, respectively, which is about 1.8~2.6 times the value of primary agricultural products(direct economic benefits), and is about 4.8 times the total input cost. The research results provide theoretical and data supports for formulating ecological compensation policies for planting green manure in farmland in Northwest China.