粮食安全:西北地区退耕对粮食生产的可能影响

据西北五省区制定的规划或计划,到2010年将累计退耕400×104hm₂,约占现有耕地面积的1/4。按照目前的单产水平和粮食作物比例,西北地区将减少粮食产量近400×104t,相当于1996年西北地区粮食总产量的1/8。同时,退耕对当地的粮食生产存在正面影响,主要表现在:①退耕节省下来的生产要素的转移可以带来未退耕耕地粮食产量提高;②西北地区生态环境以及局地小生境的改善可以促进粮食生产、降低灾害风险。此外,农业科技进步和工程设施建设的加强,会对保留耕地上的粮食生产起到极大的推动作用。通过对西北五省区粮食单产的预测并结合人口预测可知,2010年西北地区粮食总产量可达4516.9×104t,在人均400kg、425kg和450kg水平下粮食需求分别为3936.1×104t、4182.1×104t和4428.1×104t。因此,从长远的角度来看,就西北地区整体而言将不会出现粮食短缺,但粮食盈余水平较低;而就具体省区而言,陕西、甘肃和青海三省区必须通过粮食调入才能满足本省区需求,而新疆和宁夏粮食则有一定盈余。

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.