西北荒漠灌区覆膜条件下苜蓿草地土壤理化性质的时空变化

摘要

覆膜种植是一种增温保墒、增加速效养分的栽培措施,被人们广泛应用在作物栽培上,并取得了丰硕的成果.本研究以不覆盖地膜为对照(CK),研究覆膜(FM)处理对种植紫花苜蓿(Medicago sativa)第2年、第3年和第4年土壤理化性质的影响.结果表明,FM显著降低了第2年和第4年0-20 cm土层的年平均pH(P＜0.05),分别较CK降低了2.7％和2.6％.FM的水溶性盐含量年均值、Na+含量年均值在不同采样年份,不同土层深度的变化趋势均是先升高后下降,且FM均小于CK,FM显著降低了第2年5月的0-20 cm土层水溶性盐含量(P＜0.05),较CK降低了62.9％.FM显著降低了第4年8月、10月0-20 cm土层和第2年8月20-40 cm土层的Na+含量(P＜0.05),较CK分别降低了36％、37％和39.5％.FM在一定程度上增加了不同采样年份不同土层速效氮、速效磷、速效钾及有机质含量,但未达到显著水平(P＞0.05).%As a measure to increase soil temperature,conserve soil moisture,and increase available nutrients,film mulching (FM) has been generally and successfully used for crop cultivation.In this paper,using a crop without FM as a control (CK),the effects of FM on soil physical properties in an alfalfa field were studied in the second,third,and fourth year of the crop.The annual means of soil pH in the second and fourth year in the 0 to 20 cm depth soil layer in FM treatment were significantly decreased,and were 2.7％ and 2.6％ lower than those in CK.The annual mean values of water-soluble salt and Na+ content in FM treatment increased at first and then decreased over time,as they did in each soil layer depths.Both of the values in FM treatment were inferior to those in CK.FM significantly decreased the water-soluble salt content in May of the second year in the 0 to 20 cm depth soil layer by 62.9 ％ compared with CK.The Na+ content in August and October of the fourth year in the 0 to 20 cm depth soil layer and in August of the second year in the 20 to 40 cm depth soil layer in FM dropped by 36％,37％,and 39.5％,respectively,compared with that in CK.To a certain but statistically insignificant degree,FM increased the available nitrogen,available phosphorus,available potassium,and organic matter Content in different years and in different soil layer depths.