COLOR INFRARED AERIAL PHOTOGRAPHY TO IDENTIFY FORAGE LEGUMES IN HAY FIELDS
In September 1977 and 1978, color infrared (CIR) aerial photographs of mixed agricultural areas (approx. 132.7 km2) near Vernon and Carp, Ontario, and of forage legume test plots at Ottawa were taken at a scale of 1:6000. Extensive ground surveys were conducted within 2 wk after the photographic flights to verify CIR images of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), trefoil (Lotus corniculatus L.), vetch (Vicia spp.) grasses and their mixtures in the original transparencies. A number of photographic image characteristics of legumes and grasses have been illustrated by which a reliable identification and subsequent quantification of legume components were made, particularly in fields that showed decline of a crop or when the individual components grew as separate patches in the same field. Photo-interpretation difficulties existed in distinguishing the components in a very uniformly mixed crop and recently cut fields.