Reduced input of herbicides by use of optoelectronic sensors

Chemical weed control is, and will continue to be, of major importance in high-yield agriculture. However, both economical and ecological considerations dictate that further reductions in herbicide use will be necessary in the future. One method to achieve this is to localize herbicide application to the weeds. Detection of weeds against a soil or plant residue background is possible using optoelectronic sensors and such a system is described in this paper. The system distinguishes between the very different light reflecting properties of green plants and soil. Initial tests were performed under constant and reproducible simulated conditions of ambient light, soil and green plants. Under certain circumstances, such as between the rows of wide seeded crops, on fallow sites and before the emergence of crops, all green plants on a field are weeds. Thus, the first field trials were carried out on fallow sites, between rows of maize, and on conservationally tilled fields. The amount of herbicides saved was between 30 and 70%, with an efficiency of weed control of 100%. (C) 1998 Silsoe Research Institute.