California Agriculture

This project explored the effectiveness of an autoguidance system based on a real-time kinematic global positioning system (RTK GPS) accurate to the centimeter (about halfinch) in agricultural production. Our objectives were to determine the effect of spacing between cultivator disks or knives and forward tractor speed on plant damage, and of deep tillage operations on drip-tape damage. Two sets of split-plot field experiments were conducted (with processing tomato transplants and direct-seeded tomatoes) in a Yolo loam field on the UC Davis campus. No significant plant damage occurred even at 7 miles per hour (mph) forward speed and cultivator disk spacing of 2 inches from the plant line. In an additional split-plot test, there was no significant damage to drip tape when the fertilizer shank was operated 2 inches from the drip tape at 3.5 mph. This system allows for automatic steering of the tractor and implements along a path close to buried drip-tape and/or plants without damaging them, even at high operational ground speeds.