可见-近红外作物氮素光电测量仪开发

为了解决当前作物氮素含量无损检测手段欠缺问题，利用氮元素在可见-近红外波段的光谱特性，通过对两路入射光和两路反射光的测量，采用最小二乘估计法进行自动标定，开发了一种非接触测量植株氮素的光电测量仪，通过信号的调理解决了光电信号弱和太阳角影响问题。该仪器测得的双波段光谱数值与地物光谱仪相比具有很好的相关性，决定系数分别是0.994和0.985，而且能够方便地测定用于作物氮素营养评价的优化植被指数值。对小麦试验结果表明，该仪器可以用于植株氮素营养快速无损监测评价，具有操作简便、功耗低、灵敏度高、响应时间快的特点，测量的作物氮素可以用来指导变量施肥。

Development of a visible-infrared photoelectric instrument for measuring crop nitrogen

For solving the problem of non-destructive testing method for crop nutrition, a non-contact photoelectric instrument was designed. The instrument could measure the crop nitrogen according to the visible-near infrared spectral characteristics of the nitrogen. Through measuring the two-way incident light and the reflected light, the instrument could measure the vegetation index accurately according to the automatic calibration techniques based on the least squares estimation. By using the signal processing method, the problem caused by the weak signal and the sun angle was solved. This instrument measured the vegetation index conveniently, and the results had a very good correlation with the values measured by spectrometer, and the coefficients of determination were 0.994 and 0.985, respectively. The wheat experiments indicated that instrument could be used for non-destructive measuring the crop nitrogen. The instrument had the characters of low power consumption, high sensitivity and rapid response time. The crop nutrient measured by the instrument could be used for variable rate fertilization.