Seed location mapping using RTK GPS

The potential use of a real-time kinematics (RTK) GPS receiver for seed mapping with a high level of accuracy was investigated. High-accuracy seed mapping can potentially be used in weed control and plant-specific crop management. A four-row Salvo 650 vacuum planter was retrofitted with an RTK GPS receiver. Four seed detector sensors (one per planting unit) were mounted directly above the planter shoes. These sensors detected the seeds as they fell through seed tubes. Two low-cost single-board computers were used to acquire data in real time and display it in the tractor cab. The first computer was interfaced to the RTK GPS unit to determine seed location and forward speed. The second computer was interfaced to a display unit mounted in the cab. The first computer obtained the GPS time and UTM coordinates every second and stored them with a reference time (time tag). This computer also monitored the seed detector sensors, time-tagged the seeds from each unit, and stored the information in memory. The second computer monitored the first computer and reported the planter’s performance through the display unit mounted in the tractor cab. Field tests were conducted to check the performance of this planter over two growing seasons. The first year test results indicated a need to control the sensitivity of the seed detector sensors used for seed detection. The second year tests showed that the improved system performed very well. The differences between the actual plant and the seed map generated by the RTK GPS based planter were in the range of 30 to 38 mm.