Determination of nitrogen in soil using near infrared sensor
Answers
Near-infrared sensors have been widely used in soil nitrogen detection, and relevant scholars have studied the characteristic bands, modeling methods and other aspects. However, in practice, the nitrogen content detection accuracy is not high when the soil is not pretreated well because of the soil water content [15], soil particle size and soil surface roughness [16]. Hernandez, et al. investigated the effect of soil particle size and soil moisture content on soil spectral properties. It was found that if the soil particle size is too large or too small it would affect the accuracy of near-infrared sensors to predict soil organic nitrogen, and the NIR prediction results were not ideal when the soil water content was heavy [17]. Wang studied the soil moisture by detecting the effect of soil organic matter with different water contents using a near infrared sensor. The results showed that the water would mask the characteristic wavelength bands of the soil organic matter and could interfere with the detection of soil organic matter [18]. Zeng et al. studied the effect of water on the content of organic matter detection in purple soil by near infrared spectroscopy. The genetic algorithm, two polynomial fittings and PLS were used to process the spectral data. The results showed that the proposed method could effectively eliminate the influence of purple soil moisture on the prediction of the organic matter content [19]. Zhu used PLS to study the effects of soil moisture and soil particle size on total soil nitrogen detection. The experimental results showed that the smaller the soil water content was and the smaller the soil particles was and the better the accuracy and effectiveness of the detection were [20,21]. However, there are relatively few studies on the strict pretreatment of soil. Soil pretreatment can not only improve the accuracy in detecting soil nitrogen content by near infrared reflectance sensor, but also has a good scientific and practical value.
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