[Evaluation of agricultural net primary productivity in Yijinhuoluo County, Inner Mongolia]

An agricultural net primary productivity model considering both climatic and fertilizer factors was presented, with referencing over 40 years (1959-1998) climatic and agricultural data from Yijinhuoluo County. Based on the scenarios of climate, population and human activities (mainly fertilization) in the next 30 years as well as the demand of local people for food, the changes of the crop area were evaluated. As a result, 622-5948 hm2 could be converted into grassland and forest land from now to the year of 2010, amounting to 3%-31% of the average area between 1990 and 1998; from 2010 to 2020, the converted area should be 3263-8164 hm2, amounting to 17%-42%. In the next 10 years, the area of cropland would rise slightly because of the limitation of increasing yield and population.