Squeezing More Crop Out of Each Drop of Water
By Don Comis
October 8, 2009
Studies in China and Colorado by
Agricultural Research Service (ARS)
scientists and cooperators have revealed some interesting tactics on how to
irrigate with limited water, based on a crops critical growth stages.
Ahuja, research leader at the
Agricultural Systems Research Unit in Fort Collins, Colo., and colleagues
conducted the studies.
As one example, with wheat in China, they found it best to use 80 percent of
the water for wheats two critical growth stages. In Colorado, it was best
to use 80 percent of the water for corns critical flowering and grain
Other tactics for putting limited water to best use are to irrigate only
part of a field, skip the pre-plant irrigation for corn, delay irrigating until
up to half of the soil water is depleted, and wet soil to no more than 70
percent of field capacity.
Ahuja and his colleagues came up with the findings in China by combining the
ARS Root Zone Water
Quality Model with the Decision Support System for Agrotechnology Transfer
crop growth modules.
While the combination of models has been used in other experiments to test
alternative water and nitrogen management practices, this is the first time
these models have been used to evaluate crop responses to lack of water across
critical crop growth stages, and the first to use long-term weather data.
In Colorado, they used the models for simulations, relying on local weather
records dating back to 1912. In China, the simulations used records from 1961
The scientists also found that farmers irrigating in China could cut back
their nitrogen fertilizer use by a third, reducing nitrate leaching by 60
percent without affecting crop yields.
The experiments demonstrated that crop simulation models enable fast and
cheap transfer of technology from research labs and experimental stations to
farmers fields. Coupled with local field experiments, they proved to be
an excellent tool for making the best use of limited water.
more about this research in the October 2009 issue of Agricultural
ARS is the principal intramural scientific research agency in the
U.S. Department of Agriculture.