Automatic Control of a Finger Weeder with Respect to the Harrowing Intensity at Varying Soil Structures

Abstract When finger weeders are used for weed control the treatment effect will vary, depending on the state of the soil. In 1995, a pilot project was carried out to examine the possibility of using sensor/control technology to reduce variations in the weed control caused by variations in soil conditions. The object was to verify that weed covering depends on working depth and that reduction of this variation could be achieved by controlling the tine angle on the basis of working depth measurements. A finger weeder was equipped with a sensor for measuring the working depth, and the signal from this sensor was transmitted to a control system. The purpose of the control system was to maintain a fixed working depth by controlling the angle of the harrow tines. Experiments were carried out in experimental plots sown with “weed plants”. The experiments showed a clear relationship between the working depth and the weed covering achieved. Furthermore, the experiments showed that the sensor/control system is able to keep the working depth almost constant and so minimize variations in weed covering by soil.