WSPC01494

• File Number: 8064.100
• Description: Ute Tribes
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 12/1/1986
• Author: Boyle Engineering
• Title: Southern Ute and Ute Mountain - Ute Indian Reservations - Agronomy Study - Sections 1-5
• Water Supply Pro - Doc Type: Report/Study

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1885
Precipitation is important for crop production, but if rain falls
during certain growth periods, severe crop damage can occur. For

example, rainfall during the harvest period of cereal grains or corn

can cause lodging which usually makes harvest difficult and
increases harvest losses. Dryland crops rely on precipitation to
provide their water requirement and crop yield is directly related to
the amount of precipitation that occurs both annually and during the
growing season. Precipitation during the growing season (generally
April through September) is considered the most important; however/
precipitation that occurs during the winter also contributes to crop
growth by increasing the amount of moisture stored in the soil which

is available for future crop uptake. This stored soil moisture is

available to the plant for use during the growing season.

Guidelines which specifically relate the amount of annual or
seasonal precipitation to crop suitability or yield are lacking.
There are several site specific variables that must be evaluated in
order to determine the suitability of a particular area to dryland
crop production. Not all rainfall is effective in satisfying the
crop consumptive use requirement. Water losses occur as a result of
evaporation, runoff, and deep percolation. Short, light intensity
rainfall does not provide significant effective precipitation since

much of this water is lost through evaporation. Conversely, an

intense rain is often lost as a result of runoff or deep percolation.

Soil conditions also affect the amount of rainfall effective in
satisfying crop consumptive use. Soils with low infiltration rates

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