利用土壤的近红外光谱特征测定土壤含水量

以新疆玛纳斯县不同质地土壤(砂壤土、粉粘壤土和粘土)室内光谱反射率作为研究对象，采用包络线去除法对土壤光谱曲线进行处理，与土壤含水量进行相关分析并建立模型。结果表明：不同质地土壤光谱反射率大小依次为：粘土>粉粘壤土>砂壤土;砂壤土、粉粘壤土和粘土分别以田间持水量20.01%，24.10%和30.43%为临界点，在低于该临界点范围内含水量与反射率呈反比，在高于该临界点范围内含水量与反射率呈正比;在1 390～1 623 nm波段内，土壤含水量与光谱归一化反射率有较好的负相关，并达到显著水平，所建立的土壤含水量预测模型R2值达到0.8以上，模型平均相对误差为10%。结果表明，建立不同质地土壤含水量光谱预测模型可以较准确反映土壤含水量，其快速、无损、准确的优点，为测定土壤含水量提供了一种新方法。

Measuring Soil Water Content by Using Near Infrared Spectral Characteristics of Soil

Different textured soils(sandy loam,silty clay loam and clay) from Manas County,Xinjiang were researched with indoor spectral reflectance,continuum removal was used to process soil spectra curve,and correlation analysis was made about normalized spectral reflectance and water content for modeling.The results show that different textured soils have reflectance in a order that clay>silty clay loam>sandy loam;the critical points of field capacity in sandy loam,silty clay loam and clay were 20.01%,24.10% and 30.43% respectively,and water content was inversely proportional to spectral reflectance below such critical points while proportional above the points.Within 1 390~1 623 nm band,the negative correlation coefficients of soil water content and normalized spectra reflectance show better negative correlation and reaching significant levels,R2 of the model established for soil water content prediction exceeded mostly 0.8,and the average relative error of the model was 10%.The model could accurately reflect the soil moisture content,Its advantages such as accuracy,non-destruction and rapidness provide a new approach to measuring soil water content.