Kansas State University researchers are studying the feasibility of using land that had been enrolled in the U.S. Department of Agriculture’s Conservation Reserve Program to grow plants for the biomass market.

K-State range scientist Keith Harmoney points out that when the project started in 2008, Kansas had about 3 million acres in CRP land, but by the end of 2011 about 50% of those CRP contracts will expire.

Harmoney, based at KSU’s Agricultural Research Center in Hays, is studying different ways to manage former CRP land that could produce biomass while retaining water quality, wildlife habitat and soil conservation benefits.

“We're looking to see if there are other ways that producers can utilize the CRP lands without putting them back into row crops,” he said of the 5-year study that began in 2008 and is scheduled to end with the harvest in 2012.

Kansas is one of six states involved in the study, and the 18-acre CRP site near Hays is the only site in Kansas. Other states in the study are Montana, North Dakota, Oklahoma, Missouri and Georgia.

The research, sponsored by the U.S. Department of Energy and Sun Grant Initiative, examines different management strategies, including using no nitrogen fertilizer, applying 50 pounds of N per acre and applying 100 pounds of N per acre.

The dominant grasses on the acreage are sideoats grama, indiangrass, little bluestem, switchgrass and big bluestem. A significant amount of yellow sweetclover is also present. 

“The harvest management we’re studying is close to peak standing crop, shortly after the mid-point of summer, after July 15, and the other is at the end of the season after the first frost,” Harmoney said. The July 15 date is important because it marks the end of the Kansas grassland bird-nesting season, so harvesting after that date, in late July or early August, avoids disturbing any nesting birds.

“This research project is a little bit different than your typical plot research experiments,” the range scientist said. “It’s much larger scale. Each of the plots is one acre in size, which means we’ve been able to use typical field scale equipment to harvest the plots -- just like the swathers and balers that producers would use.”

The stand was cut to a height of 6 inches, leaving a 6-inch stubble to maintain soil and water erosion.

The research so far shows that while fertilizing with 50 or 100 pounds of nitrogen per acre statistically increased yield over the non-fertilized treatment, the overall increase was not as efficient as expected, Harmoney said.

“Nitrogen fertilization has increased productivity,” he said. “We’ve been able to increase production by about 600 pounds per acre from having 50 pounds of nitrogen fertilizer, and just a little over 1,000 pounds an acre from utilizing 100 pounds of nitrogen per acre,” but noted that with current rates of production and returns, harvesting biomass from CRP land without adding N fertilizer is more profitable.

As part of the study, the researchers are tracking plant populations and plant composition to see how they’ve changed over time due to harvest management and nitrogen treatments.

“We’ve also collected soil samples so we’ll be able to track how soil nutrient status has changed over time, as well as some of the other soil properties,” Harmoney said.

After the 10-year contract expires on CRP program acres, producers have often had the option to re-enroll in CRP or to plant back to row crops, he said. Since the study began, thousands of Kansas CRP acres have been planted back to grain crops, but thousands of CRP acres have also been re- enrolled with new contracts. 

“This project is important because Kansas currently has about 2.5 million acres of CRP lands, much of which will soon be coming out of the program, so any research that involves CRP has the potential to have a big impact and affect a large acreage of Kansas lands,” the researcher said.