Precision Agriculture and Implement Systems
Core concepts
Know GPS/GNSS guidance, RTK correction, auto-steer, section control, variable-rate application, and ISOBUS communication between tractor and implement. Understand yield monitoring, prescription maps, and telematics. Implement systems include seeding rate control, sprayer rate control (flow-based and PWM), and baler monitoring. Know sensor calibration and the difference between GPS position accuracy and repeatability.
Traps
Questions often confuse RTK accuracy with standard GPS or assume auto-steer corrects implement drift without a separate implement guidance system. Another trap is mixing rate control methods: flow-based adjusts valve, PWM pulses nozzles. Calibration errors in wheel slip or flow meters skew application rates. ISOBUS compatibility is not universal.
Rule of thumb
Application rate = flow / (speed x swath width), with consistent units. Verify speed source (radar, GPS, wheel) and flow calibration before trusting the rate. For RTK, repeatability matters more than absolute accuracy for pass-to-pass guidance.
Worked example
A sprayer targets 100 L/ha at 10 km/h with a 24 m boom. Required flow = 100 L/ha x 10,000 m²/ha conversion: flow = rate x speed x width / 600 = 100 x 10 x 24 / 600 = 40 L/min. If the flow meter reads 36 L/min, recalibrate or check for nozzle wear before adjusting the controller.