中国农田生产系统土壤保持功能及其经济价值

农田生产系统不仅为人类提供了多种多样的农产品,同时,农作物对地表的覆盖以及各种水土保持措施的采用,使农田生产系统也发挥着重要的土壤保持功能。根据计算,我国农田生产系统每年保持土壤的数量为101.9×108t,其中,西南地区、黄土高原区和东北地区的农田土壤保持功能最为突出。采用市场价格法、机会成本法和影子工程法对农田保持土壤的价值进行评估,结果表明:我国农田每年保持土壤养分的价值为4408.50×108元/a,减少耕地废弃价值为164.09×108元/a,减轻淤积的价值为53.74×108元/a,总计4626.66×108元/a,相当于2000~2002年我国种植业平均产值的32.08%。其中,东北地区、黄土高原区和西南地区保持土壤价值较大,合计为2851.8×108元,占总价值的61.6%。

Services for Soil Conservation and Its Monetary Value of Chinese Cropping System

Chinese cropping system not only provides people grains, vegetables, etc., but also takes an important role in soil conservation. First, crops reduce soil erosion through increasing soil penetrability and reducing runoff. Second, Chinese farmers invented many of measures for soil conservation in the long term of farming practice, such as terrace, check-dam, contour farming, straw mulch, etc., all of these are proved effective in soil conservation and crops yield improvement. According to the calculated results in the paper, the weight of soil conserved by Chinese cropping system is 101.910~8 t per year, and cropping systems in Southwestern China, Loess Plateau and Northeastern China are outstanding in soil conservation. Monetary value of soil held by Chinese cropping system is also calculated by methods of market price, opportunity cost and shadow cost. The results show that the total monetary value is 4 626.6610~8 yuan per year, which accounts for 32.08% of the mean output value of Chinese cropping production during 20002002. The values of keeping soil nutrients, reducing soil abandon and alleviating sedimentation are 4 408.5010~8 yuan/a, 164.0910~8 yuan/a and 53.7410~8 yuan/a, respectively. The monetary value in Northeastern China, Loess Plateau and Southwestern China are greater, and sum of them is 2 851.810~8 yuan/a and accounts for 61.6% of total monetary value of soil conservation service provided by Chinese cropping system.