Automatic GPS-based intra-row weed knife control system for transplanted row crops

Automated, non-chemical, intra-row weed control techniques for commercial crop production systems are an important and challenging task in industrialized countries. This study describes a fully automatic intra-row mechanical weed knife path control system for transplanted row crops. A real-time kinematics (RTK) global positioning system (GPS) was used to automatically detect crop planting geopositions and to control the path of a pair of intra-row weed knives travelling between crop plants along row centerline. RTK-GPS was utilized for autoguidance in seedbed preparation, and with automatic on-the-fly tomato geoposition mapping during transplanting. Trials in a Californian processing tomato field demonstrated that the intra-row weed knives successfully circumvented all 682 tomato plants in the study with no crop fatalities in trials conduced at continuous forward travel speeds of 0.8 and 1.6km/h. Field trial results showed that the GPS-based control system had a mean error of 0.8cm in centering the actual uncultivated close-to-crop zone about the tomato main stems with standard deviations of 1.75 and 3.28cm when travelling at speeds of 0.8 and 1.6km/h, respectively. Maintenance of the size of the operator’s selected close-to-crop zone size was within ±0.5cm of the target size on average with a standard deviation of 0.94cm at 0.8km/h and 1.39cm at 1.6km/h. These results demonstrate the feasibility of using RTK-GPS to automatically control a the path of mechanical weed knives operating in the intra-row zone between crop plants for automatic mechanical intra-row weed control in sustainable row crop production systems.