Farmers who irrigate their crops could save more than $9 per acre each year if they used readily available methods to schedule their water applications. Engineers with the Agricultural Research Service helped develop the scheduling programs. The engineers used economic data from a recently completed 10-year study on a 4,200-acre farm in south-central Kansas.

Researchers say farmers who use scheduling programs apply about 20 percent less water than their neighbors who water when crops simply "look thirsty." Pumping less water cuts energy use and reduces the risk of flushing fertilizer below crop roots. That saves about $12.50 per acre, while implementing one of the scheduling programs costs about $3.25 per acre.

Five percent of the 190,000 irrigated farms in the 27 leading agricultural states use a commercial scheduling service. Another 2.5 percent use their own computers to generate a schedule. The computer programs calculate crop water needs by incorporating local weather data with complex equations that account for all water used--including that transpired from plant leaves and soil surfaces.

Scheduling programs help growers cut water use and reduce nitrogen leaching three ways: watering to only shallow depths early in the growing season when roots are just developing, irrigating precisely after crops have consumed natural rainfall, and allowing crops to deplete all water in the root zone at the end of the growing season.

This data should help convince reluctant growers to include scheduling as part of their overall management program. Many farmers resist the idea because they are skeptical of cost savings or unwilling to spend the additional time and money required to schedule applications.

Scientific contact: Gerald W. Buchleiter, USDA-ARS Water Management Research Unit, Fort Collins, Colo., phone (970) 491-8213, fax (970) 491-8247, jerry@lily.colostate.edu.