Food security:the impact of land conversion from farmland to forest or grassland on grain production in Northwest China

The conversion from farmland to forest or grassland is an effective way to make North-west China beautiful,but necessarily it may influence the grain production of that region.Accord-ing to the plan made by the five provinces /municipalities,till2010the accumulative total area of farmland to be converted to forest or grassland is about 400×10 4 ha,or24.8%of the total farmland area.That is to say,400×10 4 t grain(12.4%of the total grain production in1996)will be minified in Northwest China.Simultaneously positive impacts caused by this kind of conver-sion must be seen.They are expatiated as below:(1)the transfer of water,fertilizer etc.to re-served farmland can bring more marginal profit;and(2)the improvement of ecological condi tion and local environment can promote grain production and reduce the risk of natural disasters.Furthermore,the advancement in agricultural science and technology,and the construction of a-gricultural infrastructure must make reserved farmland more productive.After predicting we can see that the total yield of grain in Northwest China will hit4516.9×10 4 t,and the demand of grain,respectively based on the different level-400kg,425kg or450kg per capita,is about 3936.1×10 4 t,4182.1×10 4 t or4428.1×10 4 t.Then a conclusion can be drawn that from the long-term point of view the grain shortage will not appear in Northwest China on the whole,but the situation is austere.To achieve the equilibrium of demand and supply,Shaanxi,Gansu and Qing-hai must import grain from Xinjiang and Ningxia.