Li Min-Zan, Pan Luan, Zheng Li-Hua, An Xiao-Fei
Key Laboratory of Modern Precision Agriculture System Integration Research of the Ministry of Education, China Agricultural University, Beijing 100083, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2010 Apr;30(4):1146-50.
A portable soil organic matter detector based on near infrared diffuse reflectance was developed. The detector uses a microprocessor 89S52 as the micro controller unit (MCU) and consists of an optical system and a control system. The optical system includes an 850 nm near-infrared LED lamp-house, a lamp-house driving-circuit, a Y type optical fiber, a probe, and a photoelectric sensor. The control system includes an amplifying circuit, an A/D circuit, a display circuit with LCD, and a storage circuit with USB interface. Firstly the single waveband optical signal from the near-infrared LED is transferred to the surface of the target soil via the incidence fibers. Then the reflected optical signal is collected and transferred to the photoelectric sensor, where the optical signal is converted to the electrical signal. Subsequently, the obtained electrical signal is processed by 89S52 MCU. Finally, the calculated soil organic matter content is displayed on the LCD and stored in the USB disk. The calibration experiments using the estimation model of the soil organic matter were conducted. Thirteen kinds of natural soil samples were prepared, each divided into five sub-samples. After measurement, the natural samples were dried under the condition of 105 degrees C for 24 h, and then the same measurements were performed. The analysis of the correlation between the detected SOM content and the measured reflectance was carried out. For the natural soil samples, R2 = 0.907, while R2 reached 0.963 for the dried soil samples. The average reflectance of the five sub-samples from the same kind soil was calculated for each kind of soil. And then the same correlation analysis was conducted, for the natural samples R2 = 0.950, and for the dried samples R2 = 0.982. The results showed that the developed detector is practical. And the soil moisture has an effect on the accuracy of the detector. It is necessary to correct the real time measurement result of the detector based on soil moisture.
研制了一种基于近红外漫反射的便携式土壤有机质检测仪。该检测仪采用微处理器89S52作为微控制单元（MCU），由光学系统和控制系统组成。光学系统包括一个850nm近红外发光二极管灯室、一个灯室驱动电路、一根Y型光纤、一个探头和一个光电传感器。控制系统包括放大电路、A/D电路、带LCD的显示电路和带USB接口的存储电路。首先，来自近红外发光二极管的单波段光信号通过入射光纤传输到目标土壤表面。然后，反射光信号被收集并传输到光电传感器，在那里光信号被转换为电信号。随后，所获得的电信号由89S52 MCU进行处理。最后，计算得到的土壤有机质含量显示在LCD上并存储在U盘里。利用土壤有机质估算模型进行了校准实验。制备了13种天然土壤样品，每种样品分为5个子样品。测量后，天然样品在105℃条件下干燥24小时，然后进行相同的测量。对检测到的土壤有机质含量与测量反射率之间的相关性进行了分析。对于天然土壤样品，R2 = 0.907，而对于干燥土壤样品，R2达到0.963。计算了每种土壤同一种土壤的5个子样品的平均反射率。然后进行相同的相关性分析，天然样品的R2 = 0.950，干燥样品的R2 = 0.982。结果表明，所研制的检测仪具有实用性。而且土壤湿度对检测仪的准确性有影响。有必要根据土壤湿度对检测仪的实时测量结果进行校正。
