新疆精河流域不同土地利用方式对土壤质量的影响

Effects of Land Use on Soil Quality in Jinghe Basin of Xinjiang

通过精河流域不同土地利用类型和农田耕作措施对土壤质量的影响研究发现:①土壤盐渍化程度呈梯度变化,即从洪积扇下部经冲积平原至沙漠,依次出现中盐渍土-强盐渍土-盐土-非盐渍土类型。②天然绿洲的土壤有机质、速效钾、有效磷和碱解氮平均含量最高。荒漠土壤的养分含量很低,但养分含量与盐渍化成正相关,因此利用盐生植物资源增加盐成土荒漠的植被盖度,也是改良盐碱土的良好途径。③人工绿洲土壤有机质和速效钾的含量水平相对较低,主要是只重视施用化肥,却忽视诸如有机肥与化肥结合使用等利于有机质和钾肥积累的耕作措施。④人工绿洲各养分要素的变异系数最低,这是由于近年来精河流域以棉花作为主要的农作物种植,化肥的施用水平较为一致。⑤土壤水溶性盐分(全盐量)随耕作年限的增长表现出先降低又升高的趋势;土壤养分含量的指标变化趋势也基本相似,即先增加而后开始下降,其中有机质含量变化较为明显。主要与多年来棉花长期连作、不合理的灌溉及农田重用轻养等有关。

Through research for the impact on soil quality by four land use types and the cultivation measure,the following conclusions could be drawn.① The soil salinization presented the gradient change,namely from the under part of diluvia fan,the alluvial plain to the desert,the soil types alternately presented medium sanitized soil,highly sanitized soil,sanitized soil and non-sanitized soil.②The average contents of soil organic matter,available potassium,available phosphorus and available nitrogen in natural oasis were higher than the contents of the other three kinds of land use patterns.The content of nutrient in the desert was very low,but the content of nutrient had positive correlation to salinization,so it was an important means to improve land productive potentialities to prevent and control the salinization by utilizing salt catch plant resources,increasing salt vegetation coverage.③The contents of soil organic matter and available potassium in the artificial oasis were relatively low.The main reason was that more emphasis was taken on chemical fertilizer during the agriculture production,but ignored the combination of chemical fertilizer and organic manure which was helpful the accumulation of organic matter and potassium.④ Owing to the comparatively unanimous chemical fertilization on cotton which was the main crop in Jinghe basin,each nutrient element in the artificial oasis presented lower variance coefficient than other three kinds of land use patterns.⑤ The change of soil water soluble salt contents firstly decreased to the valley value then turned to increase stably with the accumulation of cultivation time,and the other soil elements showed the similar change trend,especially organic matter change was comparatively obvious among them.These changes had important relationship to continuous cotton cultivation,unreasonable irrigation and exhaustive utilization of farmland,etc.