Mehlich 3浸提土壤养分的影响因素研究

Study on Influencing Factors of Soil NutrientContent by Mehlich 3 Leaching

Mehlich 3浸提剂被应用于浸提土壤中多种有效养分,但对方法的影响因素研究报道较少。选择重庆紫色土和河北的潮土两种土壤样品,设计L9(34)正交试验,设置液土比(A)、振荡时间(B)、振荡温度(C)、浸提液pH值(D)4个因素,对Mehlich 3法的浸提条件进行研究,浸提液使用电感耦合等离子体发射光谱(ICP-OES)法测定元素含量。结果表明:对于土壤中的养分浸提影响因素依次为浸提液pH值>浸提液体积>振荡时间>振荡温度,结合经济效益以及显著性,综合各因素最优组合为A1B1C1D1,即加入pH值为2.5的浸提液25 mL,在20℃下振荡5 min。在最优条件下,除B元素外,其他元素测定值的相对标准偏差RSD在0.39%~4.2%,精密度良好。方法绿色环保、成本低、实用性强,适合土壤养分含量的测定。

The extracting agent of Mehlich 3 has been used to extract and determine various available nutrients in the soil.However,there are few studies on the influencing factors of this method.We selected two soil samples such as purple soil from Chongqing and aquatic soil from Hebei.Orthogonal test with L 9(34)was designed four factors including the volume of extract solution(A),shaking time(B),shaking temperature(C),and pH of extraction solution(D)were set to study extraction conditions of using the Mehlich 3.The element concentrations of the extract were determined by inductively coupled plasma emission spectrometer(ICP-OES).The results showed the amount of soil available nutrients increased with increasing pH of the extract solution.oscillation temperature had less influence on the content of soil nutrients.Considering the economic benefits and significance,it is suggested that the optimal conditions for extracting soil nutrients by Mehlich 3 were A1B1C1D1.A portion of 5.00 g of the air-dried soil samples was added with 25.0 mL of Mehlich 3 extraction solution with a pH of 2.5,which was shaken at 20℃for 5 min.Under optimal conditions,the relative standard deviation of elements is between 0.39%and 4.2%,with good precision except for the B element.The method is green,low-cost,practical,and suitable for the determination of soil nutrient content.