产量比系数对农用地分等的影响

产量比系数是农用地分等中关键的参数，其测算的是否科学决定了农用地利用等别评价精度，由于中国耕作制度的复杂性和利用方式的多样性，农用地分等规程上要求采用基准作物和指定作物最高产量比法求取产量比系数，如何进行产量比系数改进，提高农用地分等精度是必须要解决的科学问题。该文以上海市崇明区作为研究案例，针对一年两熟区域农用地分等，采用最高产量比法、生产潜力比法、热量比法、市场价格比法、热量—现实生产力综合比法、热量—生产潜力综合比法等6种方法确定产量比系数，并检验不同方法确定产量比系数对农用地自然质量等别和利用等别的影响。研究结果表明，与规程确定的产量比系数方法评价出的农用地自然质量等别和利用等别比较，其他5种方法评价得出的农用地自然质量、利用等别呈现整体上升或整体下降趋势。但是，依据不同方法确定的产量比系数进行农用地评价，对农用地自然质量等别和利用等别的空间质量差异没有影响。

Impacts of productive ratio coefficient on grade of farmland classification

The farmland classification precision depends on the PRC(productive ratio coefficient) calculation. According to the standard of the farmland classification method in China, the PRC was calculated by the rate of the base crop yeild maximum and the appointed crop yield maximum, but, for the impacts of the different PRC calculation methods on the farmland classification precision was unknown. The PRC calculation methods' improvement is base of the national farmland classification standard. In the paper, Chongming county in Shangha was taken as a case study, the other five PRC calculation methods except for the standard method were brought out, to show the impacts on the farmland classification precision. The results show that the different PRC can increase or decrease the natural quality grade, utilization grade index on the whole, but, grade spatial distribution orders of the relative farmland were the same. In the same cropping system, the six PRC calculation methods have the same impacts on the farmland classification precision, but the farmland index based on the different PRC has the same agricultural productivity.