Development Of Rice Side Deep Variable Rate Fertilization Control System Based On Multi-sensor Fusion

Rice was one of main food crops in China,which was the largest rice producer in the world.Fertilization was an important part of the rice production process,which directly affected the yield of rice.The large amount of fertilization and the low fertilizer utilization resulted in the deterioration of soil physical properties,the imbalance of soil nutrient structure and the pollution of groundwater and rivers in traditional artificial fertilization.Reasonable and effective use of fertilizer could increase rice yield and protect environment.Precision agriculture proposed to fertilize according to the amount of fertilizer required by crops,which required more and more intelligent agricultural equipment.At present,the side deep fertilization technology for rice was widely used.It could evenly fertilize to a certain depth on the side of the seedlings according to agronomic requirements.Compared with the traditional fertilization method,it could reduce the amount of fertilizer.But the side deep fertilization technology for rice could only carry out uniform strip fertilization,variable rate fertilization could not be carried out,and the fertilization amount could not be further reduced.In order to further reduce the amount of fertilizer applied and improve the utilization rate of fertilizer,combined with air-blast rice side deep precision fertilization technology,a variable rate fertilization system for rice side deep based on multi-sensor fusion was developed.The system was mainly composed of sensor module,data acquisition module,data processing module,serial communication module,GPS module,fertilization controller,fertilization drive motor,fertilization device,blower and vehicle display terminal.Sensor modules included ultrasonic sensor and soil conductivity sensor.Ultrasonic sensor detected the fertilization depth.Soil conductivity sensor indirectly indicated soil fertility grade.A side deep variable rate fertilization strategy was proposed based on information of fertilization depth and soil fertility grade.The target fertilizer value was sent to the fertilization controller by STM 32 microcontroller,and the controller drove fertilization motor.Under the action of motor and air blower,the fertilizer was discharged through air supply and transportation.In order to verify the performance of the side deep variable rate fertilization system,the sensor performance experiment and the corresponding platform experiment and field experiment were carried out at Beijing Xiaotangshan National Precision Agriculture Research Demonstration Station from July to September 2020.The sensor performance experiment showed that the maximum error of the ultrasonic sensor was 2.14%,and that of soil conductivity sensor was 2.82%.The system fertilization accuracy experiment showed that the maximum fertilization deviation was 5.7%.Compared with the conventional side deep fertilization method,the variable rate fertilizer application amount was effectively reduced,the maximum rate of fertilizer reduction was 16.73%,and the variable rate fertilizer application amount was effectively reduced which provided a new equipment support for precise fertilization of rice.