WSU researchers to study double-cropping trends in western U.S.

Sep. 9—Washington State University researchers have received a $100,000 grant from NASA to comb through years of satellite imagery to study a farming practice in the American West that has implications on water availability in the region.

WSU associate professor Michael Brady, who will help lead the project, said they're looking to see whether the practice of double-cropping — planting two crops in a single season rather than one — is increasing in the state as the growing season becomes longer as a result of climate change.

Researchers will analyze photos taken by NASA's Landsat program every two weeks or so since the late 1990s to see whether double-cropping practices are increasing. He said the major advantage is the ability to look at long-term trends for every field in Washington.

"That's kind of the most complete data source, the most detailed over long time periods, where we can look at the trend," Brady said. "Previous projects were kind of indirectly trying to look at it. This is a chance to just really directly try to see how much double-cropping there is."

While it would lead to a rise in food production for the region, Brady said irrigating two crops in one season takes significantly more water. He said some farmers will have the rights to divert more water and would likely do so to increase production and profit, but that would mean less for other irrigators that depend on the same water system.

The big question facing western states generally, he said, is how to meet a growing demand for water as the supply diminishes.

If their study does show an increase in double-cropping, it may help agencies like the Washington Department of Ecology to factor that into their investments in water storage, and policies surrounding management and allocation.

However, Brady said just because the season is getting longer doesn't mean growers will be able to produce another crop. He said double-cropping is already practiced in some parts of the country, including Washington, but those regions tend to be located closer to the coast where they are protected from high summer temperatures.

"With Eastern Washington ... we're likely to have a longer growing season. It's already gotten quite a bit longer in the last four or five decades," He said. "A longer growing season does seem to lead to more double-cropping, but (an) increase in those peak summer temperatures seems to reduce it, and so there's a lot of questions about what will happen in the future."

Brady said the NASA grant allows him and fellow researcher Kirti Rajagopalan with WSU's Department of Biological Systems Engineering to analyze how much double-cropping has grown. However, he said more work will have to be done to better understand the long-term implications of the practice and what can be done to manage them.

"It's not like it's a good thing or a bad thing. Obviously, if you have the diversion rights, (and) if you have a longer growing season, you're going to do it because it increases profit," Brady said. "But because of the nature of irrigation, where you rely on surface water, it's just more complicated because if one farm or groups of farms do it, it can affect other irrigators throughout the whole system."

Jackson can be reached by email to sjackson@dnews.com.