| WATER
BUDGET METHOD OF IRRIGATING TREES AND SHRUBS
Developing
a water budget to schedule irrigations for trees and shrubs is often
useful. Here's how to set one up:
- Determine
the water-holding capacity of your soil. As discussed earlier,
most High Desert soils are either sandy loam or loamy sand by
definition. Both hold between 1 to 2 inches of water per foot
of soil. For setting up your water budget, use the low end:
Each foot of soil
holds 1 inch of water
- Consider
the ultimate rooting depth of shrubs and trees:
Allow 1 1/2 feet
of water per shrub and 3 feet per tree
- To
determine the total water budget per tree, multiply 1 inch of
water-holding-capacity per each foot of soil depth:
1 inch of water/foot
x 3 feet =
3
inches of water
- To
determine the total water budget per shrub, multiply 1 inch of
water-holding-capacity per each foot of soil depth:
1 inch of water/foot
x 1.5 feet =
1.5
inches of water
- Time
irrigations accordingly. First, irrigate to fill the entire soil
depth (3' for trees, 1-1/2' for shrubs)
- Schedule
future irrigations based on "feel tests." Place some
soil in your hand from the lower depth. If it forms a ball and
does not ooze water, it is time to irrigate again.
If
the soil does not form a ball, it may be too dry. If it forms
a ball and oozes lots of water, check it again in a day or two
before you irrigate.
- Each
irrigation should fill the plant's root area completely.
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