近红外光谱技术实时测定土壤中总氮及磷含量的初步研究

及时、准确探测土壤中的氮、磷含量,有利于精准施肥决策,提高肥料利用率。研究表明近红外技术能够探测土壤的物理和养分状况。针对不同土地利用类型,在北京大兴地区采集85份土壤样品,测定土壤氮、磷养分及其近红外漫反射光谱,并利用傅里叶变换光谱技术和偏最小二乘回归法建立了土壤总氮(N)和总磷(P)的近红外光谱校正模型。所建模型的交叉检验决定系数(R2CV)分别为0.8626(N),0.6685(P)。用未参与建模的10个样品对模型进行外部检验,总N、总P的预测相关系数(r)分别为0.9698,0.8307,预测标准误差(RMSEP)分别为0.0095%(N),0.0086%(P),RPD值(检验集样品化学测定值标准差/预测标准误差)分别为3.78(N),1.69(P)。结果表明,采用适当的光谱分析方法可以实现用近红外技术对土壤总N的精确探测及对土壤总P的粗略估测。

Real-Time Analysis of Soil N and P with Near Infrared Diffuse Reflectance Spectroscopy

Improving the efficiency of fertilization is an effective method of enhancing income for farmers,but it depends on measuring the soil nutrients accurately and rapidly.Near infrared reflectance spectroscopy(NIRS) is a fast method to detect the soil nutrients.In order to evaluate the feasibility of using NIRS to determine the soil N and P contents,the soil samples were collected from different LULC(land use and land cover) types in Daxing district,Beijing,and their biochemical parameters were determined by traditional chemical method.Then,the near infrared reflectance spectra of the samples were acquired,and NIRS models were built using partial least square regression(PLS) and Fourier transform technology for the total N and total P.The determination coefficients of cross validation for the total N and total P were 0.862 6 and 0.668 5 respectively.Ten samples were used to test the performance of the models.The coefficients of correlation between the chemically determined value and the NIRS predicted one were 0.969 8(N) and 0.830 7(P) respectively.The root mean standard error of prediction for N and P were 0.009 5(%) and 0.008 6(%),respectively.The ratios of RMSEP to SD(RPD) were 3.78(N) and 1.69(P).The results showed that the NIRS could be used to evaluate the soil N accurately and the soil P roughly.