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以渭干河-库车河三角洲绿洲连作5、10、15、20 a和25 a的棉田土壤为研究对象,对棉田土壤的理化性质和酶活性进行分析。结果表明:随着棉花连作年限的增长棉田土壤容重增大、孔隙度下降,粗砂和细沙含量增加,粘粒含量下降,其变化连作15 a极为明显;随着连作年限的增长盐分含量和pH值逐渐降低,有机质和碱解氮含量大幅度升高,速效磷比较稳定或略有减小,而钾的含量显著下降,致使氮、磷、钾比例失调,其增减变化连作15a极为显著;随着连作年限的增长脲酶、过氧化氢酶和转化酶的活性呈现先升后降的趋势,连作15 a都达到最高值,蛋白酶和磷酸酶活性也呈现先升后降的趋势,但其活性连作20 a达到最高值。由研究结果可以得出研究区棉花连作年限不宜超过15 a,棉花连作年限超过15 a时,会导致土壤容重增大、孔隙度下降,土体紧实板结,结构性差,土壤养分含量失衡,酶活性降低,土壤质量下降等连作障碍,使得棉花产出和效益受到影响。
The physical and chemical properties and enzyme activities of soils in cotton fields of 5, 10, 15, 20 a and 25 a were studied with the Weigan-Kuqa River Delta oasis. The results showed that with the increase of cotton continuous cropping, soil bulk density increased, porosity decreased, coarse sand and fine sand content increased, and clay content decreased. The change of continuous cropping for 15 years was extremely obvious. With the increase of continuous cropping salt content and The pH value decreased gradually, the content of organic matter and alkaline hydrolysis increased significantly, the content of available phosphorus was stable or slightly decreased, but the content of potassium decreased significantly, which resulted in the imbalance of nitrogen, phosphorus and potassium. ; The activities of urease, catalase and invertase increased firstly and then decreased with the increasing of continuous cropping duration, reaching the highest values at 15 a after continuous cropping and the activity of protease and phosphatase also increased first and then decreased, The activity of continuous 20 a reached the highest value. From the results of the study, it can be concluded that continuous cropping of cotton in the study area should not be more than 15 years, and continuous cropping more than 15 years will lead to increase of soil bulk density, porosity, tight compaction of soil, poor structure, imbalance of soil nutrient content, Activities such as reduced activity, soil quality and other continuous obstacles, making cotton output and benefits are affected.