Influence of Vegetable Basket Project on greenhouse expansion of Nanjing City, China

Abstract: Agriculture has great significance for the national food, resource, and ecological security, closely relating to the life stability and health of every resident. The cultivated land is constantly occupied by urban construction as urbanization rapidly increases. The transfer of a large number of the rural labor force and the change of food consumption structure have caused great challenges on the production and supply of vegetable food in China. The former Ministry of Agriculture has launched the Vegetable Basket Project in 1988, to solve the tight supply of agricultural and sideline products. A Vegetable Basket Project planning aims to transform and expand the vegetable greenhouse base, with emphasis on strong resistance to natural disasters, stable and high yield, further to realize the balance of seasonal production and perennial consumption of vegetables. In remote sensing interpretation of Nanjing City from 1995 to 2017, the cultivated farmlands were retreating from the urban areas, and the vegetable producing areas were shifting from the center to the outer suburbs, while the greenhouse areas were ever-increasing, as the main source of urban construction and expansion. It is necessary to evaluate the Vegetable Basket Policy on the specific change of greenhouse areas in rapid urbanization. In this study, a field survey of farmers and policy analysis was carried out in six main greenhouse planting areas (Pukou, Lishui, Gaochun, Jiangning, Qixia and Liuhe District) in Nanjing, China. A Tobit model was used to quantify the impact of the Vegetable Basket Project on greenhouse expansion. The variables included policy factors (whether it was a vegetable production base and the distance from vegetable production base), location factors (the distance from the vegetable market and the distance from the nearest road) and terrain factor (the slope). The results showed that: 1) The Vegetable Basket Project was an important driving force of greenhouse expansion in Nanjing in recent 20 years, thereby effectively promoting the process of suburban agricultural facilities; 2) In the Vegetable Basket Policy, the most significant impact factor was the planning and construction of vegetable production base on the change of greenhouse areas; 3) The location factors, such as market and traffic, were important impacts on the area of suburban greenhouses. The change proportion of greenhouse areas decreased with the increase of the distance from the vegetable market and roads; 4) There was a regional difference in the change of greenhouse areas. Both market accessibility and traffic convenience played a positive role in the expansion of greenhouses in each district. The policy factors were dominated by the different changes in greenhouse areas. 5) In qualitative analysis, it was found that the Vegetable Basket Policy, together with agricultural, farmers' and farmland policy, promoted the transformation of farmland greenhouses in the suburbs of big cities.