下辽河平原区耕地质量演变及障碍因素诊断

目的 为探究2008—2018年下辽河平原区耕地质量演变情况，明确该区域影响耕地质量变化的障碍因素及其分布。方法 文章将2016年耕地质量等级国家标准统一应用于2008年和2018年该区域耕地质量等级评价，采用障碍度模型对2008—2018年该区域耕地质量等级评价指标影响耕地质量的障碍程度进行诊断，依据每个指标障碍度大小排序确定影响耕地质量变化的障碍因素，根据不同区域评价指标障碍程度差异确定的障碍因素进行类型组合形成分区。结果 （1）11年间下辽河平原区耕地质量等级总体呈现上升趋势，以中高等级耕地为主。其中一、二等级耕地面积上升，三至九等级耕地面积出现下降且三等地下降幅度较大，下降的区域主要包括昌图县、台安县、辽中区、辽阳县和灯塔市等地。（2）研究区主要障碍因素类型区以单一指标灌溉能力、有机质、地形部位型障碍因素类型区为主。11年间障碍因素分区整体处于稳定状态，呈现为灌溉能力型障碍因素类型区为主，主要集中在北部和东南部地区、康平县、辽中区、凌海市和黑山县部分地区，障碍因素分区结构呈现由单一重度障碍转变为多种重度障碍并存的趋势。（3）2008—2018年下辽河平原区耕地质量等级上升了0.16等，耕地质量等级保持中高水平，等级上升的区域面积高于下降的区域，灌溉能力指标是影响下辽河流域耕地质量等级变化的主要指标之一，土壤有机质在11年间有所改善但变化较少。（4）单一指标型障碍因素类型区呈现下降趋势，而含有两个重度障碍度指标的面积呈现上升趋势，且障碍因素类型区增多，呈现重度障碍度指标复杂化的趋势。结论 2008—2018年下辽河平原区耕地质量等级总体上升反映了11年间耕地质量保护与提升等政策和措施取得了一定的成效，未来耕地质量保护与提升应该在明确耕地质量等级和主控障碍因素基础上确定更加精准的目标和方向，从而实现耕地质量等级的靶向提升。

CULTIVATED QUALITY EVOLUTION AND OBSTACLE FACTORS DIAGNOSIS IN THE LOWER LIAOHE RIVER PLAIN

This research aims to investigate the evolution of cultivated land quality from 2008 to 2018 in the Lower Liaohe River Plain, so as to identify the obstacle factors and distribution of cultivated land quality change in this region. The national standard of cultivated land quality grade in 2016 was uniformly applied to evaluate cultivated land quality grade in 2008 and 2018, respectively. Moreover, the obstacle degree model was used to diagnose the obstacle degree of cultivated land quality affected by the obstacle factors. According to the obstacle degree of each factor, the obstacle factors affecting the change of cultivated land quality were determined, and the obstacle factor type zoning was determined by the combination of the obstacle degree difference of the factors in different regions. The results were indicated as follows. (1) In the past 11 years, the cultivated land quality in the study area showed an increasing trend, that was mainly in the middle and high grade. Among them, the areas of cultivated land with Grade 1 and 2 were increased, those with Grade 3 to 9 were decreased. And the decrease rate was larger in Grade 3, which was mainly distributed in Changtu county, Tai''an county, Liaozhong county, Liaoyang county, Dengta city. (2) The main obstacle factor types were the single factor type with irrigation capacity, organic matter and topographic location, respectively. In general, the obstacle factor type zoning remained stable in the past 11 years, showing the obstacle factor type zoning of the irrigation capacity type was the dominant, mainly concentrated in the northern and southeastern of the study area, Kangping county, Liaozhong county, Linghai county and Heishan county. The obstacle factor zoning structure showed a trend of changing from a single-severe-obstacle-factor type to a multiple-severe-obstacle-factor type. (3) From 2008 to 2018, the cultivated land quality grade in the study area increases by 0.16, maintaining at a medium-high level, and the increasing area was higher than the decreasing area. The irrigation capacity was one of the main factors affecting the change of cultivated land quality grade in the study area. The soil organic matter improved but changed little during the past 11 years. (4) The area of single-obstacle-factor type zoning showed a decrease trend, while that of two-severe-obstacle-factor type zoning showed an increase trend. Besides, the obstacle factor type zoning increased as well, and the severe-obstacle-factor type was complicated. Overall, the improvement of cultivated land quality grade in the Lower Liaohe River Plain from 2008 to 2018 showed that the policies and measures for protection and improvement of cultivated land quality in the past 11 years achieved certain results. In the future, more precise targets and directions should be promoted on the basis of identifying cultivated land quality grade and controlling the main obstacle factors, so as to achieve the targeted improvement of cultivated land quality grade.