Optical reflectance sensor for detecting plants

The reflectance ratio meter, an optical device for detecting weeds by measuring the ratio of reflected red and near-infrared light, is described. Experiments were conducted to evaluate the accuracy of the sensor in detecting weeds in the inter-row of growing soybeans and to characterize its sensitivity. Several methods for interpreting the signal were evaluated. The reflectance ratio meter is shown to have potential for estimating local weed populations.