Change Differences of Arable Land Productivity and Grain Self-Supply Ability at County Level in the Hilly Area of the Loess Plateau of China:A Case Study of Ansai County

The runoff of soil and water is one of the seriously ecological problems in Loess Plateau of China, which influences the agricultural sustainability. In order to conserve soil and water, since 1979, part of the slope arable land has been returned, especially after 1999. Ansai county has been designated as one of the experimental sites of the practice on returning cultivated slope land to woodland or grassland, the return speed of slope arable land has been accelerated at the stimulus of subsidiary. How to improve the arable land grain productivity and ensure the grain self-supply during the ecological building of soil and water conservation is the key, which matters the ecological environment recovery and social as well as economic development of Ansai county. On the basis of statistical data, the change differences of arable land productivity and grain self-supply ability are discussed in this paper. Based on the analysis of chosen index, such as ratio of arable land change, relative index of arable land productivity, and relative index of grain self-supply ability, it is clearly that the differences in the arable land area and the productivity between villages and towns are relatively large. It suggest that in order to ensure the reasonably speed of returning cultivated slope land to woodland or grassland, the progress rate of returning cultivated slope land to woodland or grassland in Gaoqiao village and Huaziping village should step up, while in Yanhewan towns and Zhenwudong towns should ease up, in the others villages and towns the progress rate of returning cultivated slope land to woodland or grassland is relatively reasonable.