AN ESSAY KEY FOR THE PHOTO IDENTIFICATION OF FARM CROPS AT SEVERAL INTERVALS DURING THE GROWING SEASON IN NORTHERN ILLINOIS. PART 3. PHOTO APPEARANCE OF HAY FIELDS
Abstract
An analysis was made of 23 hay fields scattered throughout a 13 1/2- sq mi area. The samples included hay in all possible associations with types of landforms, soils, and variations in farm practices. The fields may be identified easily and with accuracy. Hay fields have 2 characteristics in common with other crops in the research area. They are of the same size and form as fields of other crops, and the photo appearance of hay fields is not affected by variations in landforms and soils, and only slightly by variations in farm practices. The fields possess 5 characteristics which distinguish them from other crops on aerial photographs. The 2 cycles of growth through which hay passes are recorded on aerial photographs by a cyclic progression of tonal values. At each stage of growth, there are unique field markings (texture), tonal values, and objects associated with hay fields. The fields outnumber all other kinds of cultivated crops. Tones of hay fields during their early, middle, and late stages of growth register more darkly than any other group. There are no periodic limitations to the aerial photo identification of hay crops as there are to the identification of other crops in the research area.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1953
- Accession Number
- AD0015690
Entities
People
- Clyde F. Kohn
Organizations
- Northwestern University