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通过连续2年小区氮肥试验,在棉花不同生育期采集冠层高光谱数据并同步测定土壤氮含量,分析棉花冠层高光谱参数与土壤氮含量间的关系,建立基于植株冠层光谱的土壤氮含量估算模型。结果表明:土壤全氮含量随着施氮水平的增加而增加,且差异显著;基于棉花不同时期冠层光谱构建的14种光谱参量与土壤氮含量间的相关性有显著差异。其中,利用冠层光谱参数P_Area1100、Depth980、Area672、PPR(550,540)建立的土壤氮含量监测模型分别在蕾期、花期、铃期、吐絮期4个关键生育期对土壤氮含量的预测均达到了较高的精度,能够很好地反映棉花土壤氮素营养状况。利用植株冠层光谱参数可以很好地监测土壤氮素营养,说明利用植株冠层光谱方法监测土壤氮含量是可行的。
Through continuous 2-year plot nitrogen fertilizer experiment, the canopy hyperspectral data were acquired at different growth stages of cotton and the soil nitrogen contents were determined synchronously. The relationship between cotton canopy hyperspectral parameters and soil nitrogen content was analyzed, and the soil nitrogen Content estimation model. The results showed that soil total nitrogen content increased with the increase of nitrogen application rate, and the difference was significant. There were significant differences in the correlation between 14 kinds of spectral parameters and soil nitrogen content based on canopy spectra at different periods of cotton. Among them, the soil nitrogen content monitoring model established by canopy spectral parameters P_Area1100, Depth980, Area672 and PPR (550,540) predicted the soil nitrogen content at the four key growth stages of budding stage, flowering stage, boll stage and boll opening stage respectively High precision, can well reflect the cotton soil nitrogen nutrition. Plant canopy spectral parameters can be used to monitor soil nitrogen nutrition, which shows that it is feasible to monitor soil nitrogen content by plant canopy spectroscopy.