新疆绿洲棉花长期连作对土壤理化性状与土壤酶活性的影响

Effects of Long-Term Continuous Cropping System of Cotton on Soil Physical-Chemical Properties and Activities of Soil Enzyme in Oasis in Xinjiang

【目的】评价棉花长期连作对土壤理化和生物性状的影响。【方法】利用棉花长期连作定点微区试验,研究不同连作年限棉田土壤物理、化学性状和土壤酶活性动态变化。【结果】随着连作年限增加,棉田土壤容重下降,连作5、10、15和20年土壤有机质含量分别比种植1年的增加10.56%、18.09%、37.34%和55.64%,土壤含盐量呈上升趋势,连作5、10、15和20年含盐量分别是连作1年的122%、132%、124%和146%。随着连作年限增加土壤碱解氮含量增加,土壤有效钾含量呈下降的趋势,连作10、15和20年的土壤有效钾含量分别是连作1年的60.4%、35.9%和39.8%;有效磷含量在连作5年达到最大值,比连作1年增加25.2%,随后开始下降,连作10、15和20年之间变化幅度较小。土壤脲酶、过氧化氢酶、转化酶、蛋白酶和中性磷酸酶活性随着连作年限增加呈先下降后上升趋势,连作5年和10年土壤酶活性降低,连作10年以后又升高,土壤过氧化物酶活性随着连作时间延长而增加。【结论】在新疆绿洲棉区,棉花长期连作和秸秆还田后,土壤物理性状改善,土壤含盐量逐渐增加,有次生盐渍化倾向,土壤中氮、磷、钾比例失调。棉花连作5～10年,土壤酶活性较低,连作障碍较明显。

[ Objective ] The objective of the experiment is to study the effect of long-term cotton continuous cropping on soil physical-chemical and biological characters. [Method] Both cotton micro-experiment and conventional chemical methods were adopted to study the changes of soil physical-chemical properties and soil enzyme activities under long-term continuous cropping. [Result] Results showed that compared with 1 year cropping, both soil organic matter content and soil salt content were increased by 10.56%, 18.09%, 37.34%, 55.64% and 122%, 132%, 124%, 146%, respectively, under 5-20 years continuous cropping, while soil bulk density began to decline. With the time of continuous cropping increasing, the soil alkali-hydrolyzable N content was remarkably raised, but the soil available K content was decreased by 60.4%, 35.9% and 39.8% under 5-20 years continuous cropping, the soil available P content was enhanced in 5-year continuous cropping and then stable in 10, 15 and 20 years continuous cropping. The activities of urase, catalase, protease, invertase and phosphatase decreased in 5-10 years continuous cropping, while those enzyme activities increased in 15-20 years, the soil peroxidase activity increased with the continuous cropping year increasing. [Conclusion] In the oasis area of Xinjiang, under long-term continuous cropping, stalk returning can ameliorate soil physical characters, increase soil salt content, but soil N, P, K proportion was imbalanced. The enzyme activity of soil decreased in a short period of time （from 1 to 10 years）, the obstacles of continuous cropping were more obvious.