Impact of Returning Farmland to Grassland on Chinese Food Security——A Case Study of Gansu Province

The high yield of Chinese traditional agriculture leads to land overused and farmland reclaimed.So it is meaningful to change the unreasonable use pattern of farmland.Gansu province is studied as a case to find out the necessity of farmland converted into grassland and its impact on food security by analyzing the relevant of grain sown area,per unit yield and total yield,the grain supply and demand of Gansu and the output of different proportions of farmland converting into grassland.The result shows the necessity of returning farmland to grassland whether in aspect of limited grain production or in changes of food consumption structure.When 15%of farmland converted into grassland,the total food equivalent of the land decrease 2.3%,increase 2.6%and 16.8%under lower(3 t · hm~(-2)),secondary(6 t · hm~(-2)) and higher(10 t · hm~(-2)) productivity level,respectively.Therefore,returning farmland to grassland and developing grassland agriculture can make full use of land and contribute to food security.