837 
PORTION (ONLY) OF PROBABILISTIC KEY VALID 
FOR A SPECIFIC GROWING REGION 
1200 Degree-Day Image 
Inclusive Positive Photographic Density Range 
0.375 
0.474 
0.475 
0.574 
0.575 
0.674 
0.675 
0.774 
0.875 
0.975 
1.075 
1.175 
1.275 
1.375 
0.974 
1.074 
1.175 
1.274 
1.374 
1.474 
Spring Wheat 
0.286 
0.095 
0.181 
0.332 
0.655 
0.744 
Oats 
0.011 
0.002 
0.003 
0.017 
0.026 
0.027 
Barley 
0.027 
0.013 
0.018 
0.029 
0.039 
0.039 
Sod 
0.054 
0.029 
0.045 
0.117 
0.182 
0.170 
Summer Fallow 
0.622 
0.861 
0.753 
0.505 
0.098 
0.020 
Spring Wheat 
0.675 
0.377 
0.552 
0.717 
0.882 
0.910 
Oats 
0.004 
0.002 
0.002 
0.006 
0.006 
0.005 
Barley 
0.063 
0.050 
0.054 
0.061 
0.052 
0.047 
Sod 
0.021 
0.018 
0.022 
0.041 
0.040 
0.034 
Summer Fallow 
0.237 
0.553 
0.371 
0.176 
0.021 
0.004 
Spring Wheat 
0.762 
0.548 
0.693 
0.786 
0.882 
0.901 
Oats 
0.010 
0.005 
0.004 
0.014 
0.013 
0.012 
Barley 
0.112 
0.115 
0.106 
0.105 
0.081 
0.073 
Sod 
0.009 
0.011 
0.011 
0.018 
0.016 
0.013 
Summer Fallow 
0.107 
0.321 
0.186 
0.077 
0.008 
0.002 
Spring Wheat 
0.383 
0.154 
0.275 
0.437 
0.706 
0.762 
Oats 
0.064 
0.017 
0.022 
0.098 
0.126 
0.124 
Barley 
0.084 
0.048 
0.063 
0.087 
0.097 
0.092 
Sod 
0.004 
0.003 
0.004 
0.009 
0.012 
0.011 
Summer Fallow 
0.464 
0.778 
0.636 
0.369 
0.059 
0.011 
FIGURE 8. Section of a working probabilistic key, provided 
to illustrate one possible style for a two-date key based 
on photographic densities. The complete key from which this 
example was taken is approximately four times larger.