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Show Irrigate according to soil's "moisture bank" wide use that relates water loss from a standard stan-dard 4 foot diameter evaporation 7 pan to the amount of water lost from a crop area by both evaporation and transpiration. tran-spiration. The National Weather Service daily broadcasts area pan evaporation information in Utah on NOAA (special high frequency) radio. Contact the local county extension agent or the Weather Service for information concerning these broadcasts. Figure that the plants and soil lose moisture about 80 percent as rapidly as the pan. Multiplying the pan evaporation by .80 gives you a fair estimate of the moisture losses from the soil in your garden or field for the week. You can schedule irrigation to replace the moisture lost the "bank withdrawal" whenever . you desire so long as you do it before the moisture has dropped to about 50 percent of field capacity causing the plants to undergo moisture stress. For greatest efficency aim to replace only that moisture lost from the root zone that is sufficient to wet the soil again to field capacity (that which the soil will retain when fully saturated). Adding more water than that will cause the leaching losses mentioned earlier. When irrigating by sprinkler, you can determine how much you are applying by simply placing a few cans to collect water as it falls from the sprinkler. One inch collected in the cans indicates you have applied ap-plied one inch of water. You may find it helpful and of interest to keep a running account of your available soil moisture. Week by week over the summer simply add the moisture input from precipitation and irrigation and subtract 80 percent of the pan evaporation amount. That will tell you how much you have in your soil moisture "bank account." Schedule irrigation for your garden or fields according to your soil moisture "bank account." ac-count." State Department Depart-ment of Agriculture Climatologist E. Arlo Richardson at Utah State University says. "It's a practical; way to save costs of water, fertilizer and energy and meet your plants' needs for water." The bank account method of scheduling helps avoid water stress and having excess water infiltrate below the root zone of the plants. Excess Ex-cess infiltration moves water and leaches soil nutrients below the reach of the plant roots where they are lost to the plants. Consider the water in the soil available to the plants at any time as the current "bank balance." Realize that only the moisture down to the current depth of the plant roots is available to the plants. Also note that soils have different capacities to retain water and make it available to the plants. This ranges from about 2 inches of water per foot of soil for good silt-loam soil down to about 1 inch for sand and the heavy clay that tends to hold onto water strongly. Keep in mind that temperature, sunlight, wind and humidity are the more important weather factors which control a plant's use of water, it's "bank withrawal." In effect, the "bank depository" becomes larger as the plant roots penetrate more deeply into the soil giving an effective mature rooting depth of about 5-6 feet for fruit . trees, grapes and alfalfa; 4 feet for corn and small grain; and 2-3 feet for most mature garden vegetables. Moisture stored in this greater thickness of soil then becomes available to the roots. Irrigation that was required to be more frequent when the root systems were small and shallow can be scheduled less frequently with larger amounts as the plants grow. Plan frequency of deposits to this soil moisture "bank account" through irrigation with soil types and root depth of the particular crop in mind. Relate this to the climatic environment. Richardson said a simple method has been developed and put into |