苜蓿不同种植年限对土壤化学性状及酶活性的影响

Effects of soil chemical property and soil enzyme activity on alfalfa in desert irrigation region of Hexi

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。

The study was conducted to get a scientific management pattern of soil improvement in northwest desert region by researching the variation trends of soil chemical property and soil enzyme activity with the extension of planting years. Soil samples were taken from alfalfa field（ Medicago sativa L. cv. Gannong No. 3） with different years of planting in Hexi,whose soil nutrient content and soil enzyme activity were determined respectively. And the correlativity between soil nutrient and soil enzyme was analyzed at the same time. The results showed that the soil chemical properties of soil organic matter,total nitrogen,alkali hydrolyzable nitrogen,available phosphorus,and available potassium were improved,and soil enzyme activities of urease,sucrase,alkaline phosphatase,amylase and catalase were increased by planting alfalfa. The time for alfalfa- planting had different effects on the soil fertility and soil enzyme activity. Contents of soil organic matter and total nitrogen were the highest in 10 year alfalfa field; others were the highest in 5 year alfalfa field. Six kinds of soil chemical properties and five kinds of soil enzyme activities decreased with the increase of soil depths except p H value. Therefore,alfalfa is suitable for planting in the span of 5 years in the northwest desert irrigation.