This year, 2009, will be remembered for many events, but for Kansas State (K-State) University scientist Freddie Lamm, it also signaled 20 years of research in subsurface drip irrigation (SDI) for crops grown in western Kansas. Lamm, a research irrigation engineer with K-State Research and Extension, has worked with K-State colleagues around the state to study the pros and cons of irrigating crops by burying pipe several inches below the surface of the soil and releasing water that goes more directly to roots than alternative irrigation methods allow.

“Since we began in 1989, our SDI research and Extension efforts have had three primary purposes,” says Lamm, who is based in semi-arid northwest Kansas, where the average annual rainfall is 17 in. “Those purposes are to enhance water conservation, protect water quality and develop appropriate technologies for Great Plains conditions.”

Other K-State scientists currently active in the SDI research and Extension efforts are irrigation engineers Dan Rogers, Mahbub Alam and Abdo Shehata; agricultural economists Dan O’Brien and Troy Dumler; and soil physicist Loyd Stone.

One of the first studies, conducted at Colby and Garden City from 1989 through 1991 examined the water requirement of SDI corn.

“Careful management of SDI systems reduced net irrigation needs by nearly 25%, and still maintained top yields of about 200 bu./acre,” says Lamm. “That 25% reduction in irrigation needs potentially translated into 35-55% savings when compared to sprinkler and furrow irrigation systems, which typically operate at 85% and 65% application efficiency.”

SDI uses water more efficiently than other methods, primarily because there is less deep drainage during the crop season, less soil water evaporation and no irrigation runoff as is found in other irrigation techniques. An added benefit, he says, is that drier surface soils allow for greater infiltration of those occasional intense rains that occur in the Great Plains.

Over the years, K-State scientists have studied the use of different irrigation amounts, frequency of irrigation, drip-line spacing and depth and different plant densities. Most of the work has been with corn, because it is the primary irrigated crop in the central Great Plains. Most of the research has been conducted on deep, well-drained silt loam soils which are common in western Kansas.

“Because properly designed SDI systems have a high degree of uniformity and can apply small, frequent irrigation amounts, there are excellent opportunities to better manage nitrogen (N) fertilizer with these systems,” says Rogers. “Injecting small amounts of N solution into the irrigation water can spoon-feed the crop, while minimizing the pool of N in the soil that could be available for leaching into the groundwater.”

To read more about the potential benefits from SPI for corn on the Great Plains, click here. More information about SDI research, including detailed reports about various studies conducted by K-State over the last 20 years, is available at SDI in the Great Plains.