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研究西北荒漠灌区土壤化学性状和酶活性随种植年限的变化趋势,为荒漠绿洲灌区土壤的改良与管理提供依据。选取甘肃河西荒漠灌区撂荒地(CK)及紫花苜蓿主栽品种甘农3号(Medicago sativa L.cv.Gannong No.3)样地(种植年限分别为3,4,5,7,10年)为供试材料,分析土壤养分含量和土壤酶活性的变化规律及其相互关系。结果表明:种植苜蓿较荒地提高了土壤有机质、全N、碱解N、速效P和速效K含量,增加了土壤脲酶、蔗糖酶、碱性磷酸酶、淀粉酶和过氧化氢酶活性。不同年限苜蓿地土壤酶活性和土壤养分含量差异显著,土壤有机质、全N含量以10年生苜蓿地最高,碱解N、速效P、速效K及5种酶活性均以5年生苜蓿地最大,除p H值随土层深度的增加总体呈增加趋势外,其余指标均随土层的加深呈递减趋势。因此,在西北荒漠灌区,苜蓿适宜种植的年限为5年。
This paper studied the trend of soil chemical properties and enzyme activity with the planting years in the desert irrigation area of Northwest China and provided the basis for the improvement and management of the soil in the desert oasis irrigation district. Arid areas (CK) and alfalfa cultivars (Medicago sativa L. cv. Gannong No.3) were selected from the desert irrigation areas in Hexi of Gansu Province (planting years were 3, 4, 5, 7 and 10 years, respectively) The tested materials were used to analyze the changes of soil nutrient content and soil enzyme activities and their correlations. The results showed that the soil organic matter, total N, available N, available P and available K content were increased in the alfalfa cultivars compared with the bare land, and the soil urease, invertase, alkaline phosphatase, amylase and catalase activities were increased. The soil enzyme activities and soil nutrient contents of alfalfa in different years were significantly different. The contents of soil organic matter and total N were the highest in 10-year-old alfalfa, and the highest in 5-year-old alfalfa with alkaline hydrolysis N, available P, available K, The value of p H increases with the increase of soil depth, but the other indexes decrease with the increase of soil depth. Therefore, in the northwest desert irrigation area, the suitable planting time of alfalfa is 5 years.