光谱法土壤肥力参数实时测量在农田精细施肥中发挥着重要的作用，但土壤粒度的差异给测量结果带来了较大误差。基于傅里叶变换近红外光谱检测技术，利用PLS回归分析法研究了不同粒度土壤的反射光谱与土壤全氮含量预测结果的相关性。结果表明：相同系列全氮含量土壤样品在不同粒度（分别过20、40、60、80和100目筛）所建立的预测模型差异明显，RMSEP分别达到3.99×10-4、3.04×10-4、1.78×10-4、2.23×10-4和1.73×10-4 g/kg，显示粒度小的预测精度较高，证明了土壤粒度对近红外光谱养分检测的影响，且这种影响存在规律性。这为进一步研究消除土壤粒度影响的校正方法提供了依据。%Spectroscopic real-time measurement plays an important role on fine fertilizer in soil, but the difference of soil particle size has brought great influences on the results of the measurement. It is studied the correlation between the reflectance spectrum of different particle sizes of soil and the prediction results of total nitrogen contents of soil by means of partial least squares, which is based on Fourier transform near infrared reflectance spectroscopy detection technology. Results show that the prediction models, established by the soil samples of same total nitrogen contents with different particle sizes(20, 40, 60, 80, 100 mesh), exist significant differences, withRMSEP up to 3.99×10-4, 3.04×10-4, 1.78×10-4, 2.23×10-4 and 1.73×10-4g/kg, respectively. It is indicated that the smaller the particle size was, the higher the prediction precision was. And it is verified that the particle size has an obvious influence on soil nutrient detection with near infrared reflectance spectroscopy, which has practical values for further study on correction to particle size.
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