Making Decisions Before Drought Strikes

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Making Decisions Before Drought Strikes
The Drought Decision Calculator
Gale Dunn, USDA-ARS, Agricultural Systems
Research Unit, Fort Collins, CO
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Environmental Factors that Affect Forage Growth
This Seasons Precipitation
Other Factors Soil type Solar rad. Previous
season
Temperature
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Precipitation and Forage Growth
Long-Term Average Monthly Precipitation
Average Annual Growth Curve
Jan Feb Mar Apr May Jun Jul Aug Sep
Oct Nov Dec
Cheyenne, WY Average Precipitation 15.1 inches
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Precipitation and Forage Growth
Peak Standing Crop
Wettest Month
Jan Feb Mar Apr May Jun Jul Aug Sep
Oct Nov Dec
Cheyenne, WY Average Precipitation 15.1 inches
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Precipitation and Forage Growth
Peak Standing Crop
Peak Precipitation
Jan Feb Mar Apr May Jun Jul Aug Sep
Oct Nov Dec
Cheyenne, WY Average Precipitation 15.1 inches
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Precipitation and Forage Growth
30 of annual variation in forage production is
explained by May precipitation
Peak Standing Crop
Peak Precipitation
So What?
Jan Feb Mar Apr May Jun Jul Aug Sep
Oct Nov Dec
Cheyenne, WY Average Precipitation 15.1 inches
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Precipitation and Forage Growth
What does a knowledge of May precipitation really
Mean?
Does a reduction in May precipitation by 50 mean
a 50 reduction in peak standing crop? What if
both May and June have 50 of average
precipitation? Does that mean there is no forage
growth?
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Cheyenne
100 of Potential
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Cheyenne
19 Reduction
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Cheyenne
34 Reduction
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Drought Decision Calculator will be available
soon for the following states
North Dakota South Dakota Nebraska Montana Wyoming
Colorado Utah New Mexico Nevada