A new irrigation system in the works from USDA scientists is based on a very simple idea: Give each plant precisely the amounts of water and nutrients it needs.

The new system is part of an emerging high-tech science called “precision agriculture.” That means providing water and fertilizer to plants based on their particular needs in small areas, instead treating the whole field uniformly.

Scientists with USDA’s Agricultural Research Service started with a commercial center pivot irrigation system, which pivots in a giant circle, sprinkling plants underneath. The amount of water delivered to each plant depends on how quickly the irrigation pipe moves around the circle.

In two years of field tests, the scientists modified the sprinkler system by dividing its length into several sections. Then they gave each section three manifolds that allow the water to be sprayed from nozzles at eight different rates.

On a 15-acre field, researchers can precisely apply water and nutrients on up to 500 separate segments, each about the size of a two-car garage. The long-term goal: precise irrigation of each part of a field, based on the type of soil and crop present in that segment. This will help farmers make sure plants get enough water in sandy areas, while avoiding flooding and runoff in others with different slopes, clay content or soil compaction.

Researchers are working cooperatively with Valmont Industries, Inc., of Valley, Neb., a large manufacturer of commercial irrigation systems, to further refine the system.

Scientific contact: Carl R. Camp and E. John Sadler, Coastal Plain Soil, Water and Plant Research, Florence, SC, telephone (803) 669-5203