Vertical colour infrared air photo (Prairie Agi Photo)
Flight height: 7,200 fee a.s.l.; lens focal length: 50 mm
Scale: 1:9,800 (approx.)
Date: July 27, 1979
Location: Section 7, Township 5, Range 7WI
Map sheets: 1:250,000 62G Brandon
This colour infrared photo shows one whole section of land (section 7, township 5, range 7WI) at the foot of
For ease of identification letters are used to designate fields.
a), b), and c) these fields have been left fallow; dark green areas are low-lying and wetter, whereas light tones indicate higher, drier areas.
d), e), f), g), h), and i) are all similar in appearance: a patchy crop is growing on all of them. The light pink northeast/southwest streaks in field f) 9 are areas missed by crop treatment, possibly addition of fertilizer. Such misses used to occur in 1979 when the photo was taken, but would not happen now with modern GPS systems in place.
j), k), and l) exhibit rows of a cut crop; the circular red patches in l) 10 are probably weeds.
m) this large field is in pasture, an interpretation supported by the existence of dugouts (black) in the northwest 11 and centre 12.
n) the dark red indicates a healthy crop, probably a cereal, with a poor patch in the south 13.
o) the field exhibits the characteristic pattern of a field that has been cut.
p) is similar in general appearance to n), with some light pink streaks 14, missed during spraying. There is a distinct variation in this field; the western two-thirds has a much lower and less healthy plant population. This is often due to scleratina wilt that may occur with too tight a crop rotation.[i]
q) the light pink of this field is characteristic of sunflowers. The crop is tall, indicated by the shadow thrown along the western edge of the cut area 15.
r) a field in which some large areas 16 that are light pink have been missed during spraying. This is a remarkable example of sprayer miss. The plants giving the pink appearance are wild mustard. Properly used, a GPS guidance system would eliminate this problem.[ii]
s), t), and u) the three fields may be supporting the same crop but with different levels of success because of treatment. One field, t, seems to be the best, but even it has variations between north/south rows 17. This variation is more marked in u 18 and even more so in s 19 where there may have been some malfunction in seeding.
v) This large field shows one distinct line of stronger growth 20, probably a result of stronger soil fertility.[iii]
The ability of the interpreter to identify and explain the variations discussed enables the farmer to better plan sowing and treatment procedures and to plan for and cope with soil and drainage variations in fields.