Design and experiment of a soil organic matter sensor-based variable-rate seeding control system for maize

Variable-rate seeding technology is a precision agricultural technique that adjusts crop seeding rates according to the spatial heterogeneity of environmental factors such as soil, light, and moisture. This technology offers substantial advantages for maximizing soil yield potential, improving crop productivity, and enhancing resource utilization efficiency. Sensor-based variable-rate seeding simultaneously measures soil fertility indicators, makes seeding decisions, and adjusts rates, thereby shortening the operation cycle and increasing efficiency. Research on sensor-based variable-rate seeding remains limited. Therefore, this study used soil organic matter (SOM) as the fertility evaluation index and developed a variable-rate seeding control system based on SOM. The control system measures SOM in real-time, determines the appropriate seeding rate based on decision rules, and achieves variable-rate seeding by converting the rate into motor speed. Based on the relatively stable distribution of SOM in local areas, a fixed-distance sampling control strategy was proposed. Whenever the seeder reaches a sampling distance, it performs SOM detection, makes seeding rate decisions, and adjusts the rate, ensuring operational efficiency and quality. The control system's performance was evaluated through bench tests and field experiments. Bench tests showed that operating speed and seeding rate significantly affect the accuracy of seeding rate adjustment (SA) and the coefficient of variation in seeding rate (SCV). The control system's SA was greater than 99 %, and its SCV was lower than 0.4 %. Field test results showed that with the sensor activated, the control system's average SA was 92.03 %, its average SCV was 6.21 %, and the average lag distance was 1.13 m. The results of this study indicate that the control system can perform variable-rate seeding based on SOM.