Agricultural Research Service scientists are exploring the use of canopy cover measurements to determine how much water plants have used and how much they'll need at the next irrigation.

Knowing plants' precise water needs helps reduce over-irrigation, which can lead to leaching of fertilizer and other potential pollutants into underground water supplies.

According to agricultural engineer Thomas Trout, leader of the ARS Water Management Research Unit in Fort Collins, Colo., computres could analyze satellite imagery of farmers' fields to estimate crop canopy cover.

Growers could visit a Web site to get those measurements for their fields.

The figure, along with a few other pieces of information—such as locally relevant weather—could then be added to a standard equation to calculate the amount of water used and the amount now needed for each field.

The calculation could indicate, for example, that bell pepper plants in a field that has a canopy cover of 40 percent may have used 1 inch of water in one week, the amount the grower may choose to replenish at the next irrigation.

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