Development And Research Of Multi-parameter Combination Sensor For Soil

Soil has become the foundation of agricultural production because it has fertility and can grow plants. The soil moisture content, temperature and electrical conductivity are three important parameters of the soil which impact on crop growth and yield directly. Mostly, existing sensors or instruments which measure the above three parameters are using single measurement. Because of a larger coupling effect between these three parameters, single measurement will cause large deviations. This thesis designs a multi-parameter combination soil sensor, which can measure the soil moisture content, temperature and electrical conductivity simultaneously. Contrast experiments between different sensors conclude that the multi-parameter combination soil sensor’s performance is comparable to general instruments, so this sensor can be applied in precision farming.From the measure principle of soil moisture content, temperature and conductivity on, this thesis introduces the traditional measurements of soil moisture content, temperature and conductivity respectively. Besides, this thesis designs its supporting software and a sensor data collector. Finally, this thesis carries out a series of experiments to test the performance of the combination sensor, including calibration test, dynamic response-time test, stability test, contrastive test. These experiments’results show that the moisture content, temperature and conductivity varies with its corresponding true value in quadratic linear relationship, and the quadratic linear fitting correlation coefficients are greater than 0.9. Accuracy of moisture content measurement of the combination soil sensor, compared to the contrast instrument, is of high accuracy with error within ±2%.In conclusion, the multi-parameter combination soil sensor has good measuring precision, stability, and can measure the soil moisture content, temperature and electrical conductivity. And the combination sensor can provide a reliable and practical sensor for precision agroforestry.