Posted in | Green Farming | Biomaterials

Biomass Production from Perennial Grasslands Increases Economic Benefits of CRP Land

The Conservation Reserve Program (CRP) was established 30 years ago by the USDA’s Farm Service Agency as part of an initiative to boost habitat for sensitive wildlife species, minimize soil erosion, and enhance the quality of water. Farmers receive rent from the program in exchange for land to be removed from crop production and planted with species that enhance the quality of the environment. The land, as well as its cover crop, would be left untouched for a period of 10 to 15 years.

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A research team, led by the University of Illinois, have started to examine the economic benefits and possible biomass yield of using CRP land to fulfill the government mandates for ethanol production.

In 2008, we started long term research at the field scale. We wanted to estimate CRP biomass yield and best management practices, including nitrogen application rates and harvest timing, to maximize yield.

D.K Lee, Agronomist, University of Illinois

Lee worked with other collaborators located at CRP study sites in Oklahoma, North Dakota, Missouri, Kansas, Georgia, and Montana. All of the research sites measured 20 acres, and nitrogen fertilizer was used on one acre plots, at 0, 50, and 100 lbs per acre. Plot harvesting was done twice: at the end of the cultivating season, after a deadly frost, and/or at the summit of biomass production, which varied based on the variety of species planted at all the locations.

For cool and warm season mixtures of grass, the maximum yield reached was 6.4 and 3.5 metric tons per hectare (2.5 acres) respectively, based on the harvest timing, fertilizer application rate, and location.

Nitrogen application increased biomass yield, and we don’t have to worry as much about nitrogen runoff for perennial CRP crops like we do with row crops. Even if excess nitrogen were applied, it would be held in the system. That’s the beauty of perennials.

D.K Lee, Agronomist, University of Illinois

Even though the study systems displayed a positive outcome of the nitrogen fertilizer, economic analyzes pointed out that the increase in yield did not substantiate the costs involved in purchasing fertilizers and their application. The addition of fertilizers increased the overall functioning costs of biomass harvest up to 225%, based on location and application rate.

We also learned that precipitation during the growing season was a critical factor, since the study period included the severe drought of 2012. That result provided evidence that we need long-term studies like this one to really understand yield dynamics.

D.K Lee, Agronomist, University of Illinois

At present, farmers are not permitted to harvest biomass from CRP grassland, but despite this restriction the researchers believe that a stable production of bioenergy feedstock could help to meet the specific goals of the CRP program, especially if there is an increase in the prices of commodities.

Right now, commodity prices are low, but we know they will go up again. When that happens, people could make more money by converting CRP land back to row crops. But CRP is highly erodible land and could cause significant water quality issues if converted. Alternatively, the government may have to increase rental payments if commodity prices go up, to keep farmers from converting their CRP land.

D.K Lee, Agronomist, University of Illinois

The researchers provided a solution with a rental reduction of 25% in years when biomass from CRP land was harvested by farmers, and a compensation for harvesting one third of the acreage each year. Implementation of this could reduce the total cost undertaken by the government to operate CRP in the six CRP study sites. The total cost could be brought down by $31 million per annum.

Although this scenario would generate only one third of the potential biomass for the developing cellulosic bioenergy industry, it would allow for the utilization of otherwise unharvested lands and likely provide economic benefits for land owners, biomass processors, and the U.S. government, while preserving soil resources.

D.K Lee, Agronomist, University of Illinois

The article, “Impacts of management practices on bioenergy feedstock yield an economic feasibility on Conservation Reserve Program (CRP) grasslands” was featured in the December 2015 issue of the online journal, GCB Bioenergy. Lead author Eric Anderson, economist Madhu Khanna, and principal investigator D.K. Lee are from the University of Illinois. The paper was co-authored by contributors from six other institutions. Funding was obtained from the North Central Regional Sun Grant Center at South Dakota State University through a grant offered by the U.S. Department of Energy Office of Biomass Programs.


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