西部生态脆弱区农用地质量等别限制因素及提升策略研究

该文以云南陆良为代表的云贵高原区、重庆丰都为代表的四川盆地区、陕西凤翔为代表的黄土高原区、新疆阿勒泰为代表的西北地区以及内蒙古达拉特为代表的内蒙古及长城沿线农牧交错区为例，基于农用地分等成果，对5区农用地质量等别特征进行了系统对比分析，查明了各区农用地质量等别主要限制因素，并提出相应的提升策略，为耕地质量保护和建设政策的制定提供科学依据。研究结果表明，以上述5区为代表的西部生态脆弱区农用地等别总体偏低，农用地多为中等地和低等地，高等地分布较少，优等地无分布；有效土层厚度、有机质含量、灌溉条件是5区耕地质量等级的共同限制因素。pH值、表层土壤质地、排水条件以及盐渍化程度为西北地区和内蒙古农牧交错区特有的限制因素，岩石露出度为云贵高原区特有的限制因素，灌溉水源为黄土高原区特有的限制因素，林网化程度为西北地区特有的限制因素。在制定区域耕地质量保护与建设政策时，既要考虑共性限制因素，更要着眼于区域特有的限制因素，根据各区耕地质量等别限制因素制定相应提升策略。

RESEARCH ON LIMITING FACTORS AND PROMOTION STRATEGIES OF AGRICULTURAL LAND GRADING IN WESTERN ECOLOGICAL FRAGILE AREAS

Based on the results of agricultural land grading, taking Luliang county in Yunnan Province, Fengdu county in Chongqing City, Fengxiang county in Shanxi Province, Altay county in Xinjiang Province, Dalate county in Inner Mongolia as examples, the characteristics and differences of agricultural land grading among the five counties were compared. The limiting factors of agricultural land grading were identified, and some strategies were put forward. The results showed that the agricultural land grading in western region, as the representative of the above five counties, was relatively low, large area of agricultural land was medium and low grade with less high grade land and no distribution of excellent grade land. Effective soil layer thickness, organic matter content, irrigation condition were the common restrict factors of cultivated land grading in the five regions. And for the northwest region and farming-pastoral zone of Inner Mongolia, the characteristic limiting factors included PH value, surface soil texture, drainage condition and salinization degree, which were rock reveal degree for Yunnan-Guizhou plateau area, irrigation water for Loess plateau area, and forest coverage rate for the northwest area. Above all, when formulating policy of protection and construction of regional cultivated land grading, it should not only consider the common restrict factors, but also the regional specific limiting factors. The results in this study provided a scientific basis for the protection of land quality and the formulation of the construction policy.