水资源“三条红线”约束促使以农业用水为主的区域逐步开展退地减水措施，有效地保证了用水总量控制指标，也产生部分土地退耕撂荒的土壤质量下降问题。本文以水资源“三条红线”约束下新疆玛纳斯河灌区退耕土壤为研究对象，分析对比了退耕地块（RF）和临近耕作地块（CK）土壤pH值、可溶性总盐（TDS）、有机质（OM）、全氮（TN）、全磷（TP）、碱解氮（AN）和速效钾（AK）7个土壤质量指标，通过构建模糊综合评价模型计算RF和CK土壤肥力指数，分析水资源“三条红线”约束下玛纳斯河灌区退耕土壤质量。结果表明：（1） 退耕地块和临近耕作地块pH在7.18~8.78之间，总体上与土壤深度呈正相关。退耕地块含盐量整体比临近耕作地块高10.84%，盐分主要分布在40~100 cm。（2） 退耕地块的土壤养分整体上低于临近耕作地块，其中碱解氮差异最大，低了22.15%。（3） 退耕地块和临近耕作地块土壤肥力评价指数范围为0.49~0.77，土壤质量均在中等偏上，临近耕作地块比退耕地块肥力指数均值高6.67 %。研究结果可为灌区水资源总量约束下退地方案的实施及土壤质量保护提供理论依据。

The restriction of the “Three Red Lines” strategy of water resources makes the areas dominated by agricultural water gradually conduct “reducing water consumption by returning farmland” measures, which effectively ensures a control index of total water consumption and produces the decline of soil quality of abandoning some land after returning farmland. Taking the returning farmland soil in the Manas River irrigation area in Xinjiang as the research object under the condition of “three red lines,” this paper analyzes the indexes of soil pH value, total dissolved salt, organic matter, total nitrogen, total phosphorus, alkali hydrolyzed nitrogen (AN), and available potassium (AK), and calculates the soil fertility index of returning farmland (RF) and adjacent cultivated plots (CK) by constructing a fuzzy comprehensive evaluation model, and to perform the soil quality evaluation of RF to Manas River irrigation area under the conditions of the “Three Red Lines” strategy. The results show that: (1) The salt content of treatment RF is 10.84% higher than that of CK. Both treatments are moderately saline soil. The salt of treatment RF is mainly accumulated at 40-100 cm. (2) The soil nutrients of RF treatment were lower than CK treatment as a whole, and the difference in alkali hydro nitrogen was the largest, 22.15% lower. (3) The soil fertility evaluation index of the two treatments ranged from 0.49 to 0.77, and the soil quality was above the middle level. The average fertility index of the CK treatment was 6.67% higher than that of the RF treatment. The research results can provide a basis for implementing the land withdrawal scheme under the constraint of the total amount of water resources in the irrigation area and the protection of soil quality.