比色法快速测定土壤含水量

Rapid Detection of Soil Moisture Based on Spectrophotometry

为了建立一种准确、快速、低成本的土壤含水量的检测方法,适于在田间地头和基层实验室推广应用。笔者采用分光光度法进行土壤含水量检测,操作步骤简单,测试速度快,1个样品的测试时间可控制在5 min以内。结果表明:该体系的最大吸收波长为660 nm;显色剂的最佳浓度为3.5 g/L、最佳用量为10 m L;当Cl-浓度≤0.45 mg/L(相当于土壤中Cl-为0.45 mg/kg)时对该体系产生的误差≤1.4%,而土壤中的氯离子含量均值为0.1 mg/kg,因此,满足绝大多数土壤的检测。该法与烘干法相比,检测结果绝对误差可控制在3%以内,基本不受土壤类型和化学成分等因素的影响。该法作为一种快速、便捷检测土壤含水量的方法可行,具有推广价值和普及应用优势。

The paper aims to build a rapid test method of soil moisture content, which would be suitable forapplication in the field and the laboratory. The soil moisture content was detected by spectrophotometry, thedetection process was simple and could be controlled in 5 min for one sample. The results showed that themaximum absorption wavelength of the solution was 660 nm, the concentration and volume of chromogenicagent were 3.5 g/L and 10 mL. The error of the testing result would be 1.4% or less when the concentration of Cl^-- was 0.45 mg/L or less（the equivalent of Cl^-was 0.45 mg/kg in the soil）. Therefore, the test method of soilmoisture content was suitable for most agrotypes, because the average concentration of Cl^-- was 0.1 mg/kg. Theabsolute error of the rapid detection result was 3% or less comparing with the oven drying method, and it washardly affected by agrotype and chemical compositions. It was a rapid and convenient test method which hadpromotion value and application advantages.