Environmental Implications of Increased Bioenergy Production on Midwest Soil Landscapes

Authors: Kitchen, Newell; Sudduth, Kenneth - Ken; Sadler, Edward; Kremer, Robert; Baffaut, Claire; MYERS, DAVID - University Of Florida

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2009
Publication Date: 6/25/2009
Citation: Kitchen, N.R., Sudduth, K.A., Sadler, E.J., Kremer, R.J., Baffaut, C., Myers, D.B. 2009. Environmental Implications of Increased Bioenergy Production on Midwest Soil Landscapes. In: Proceedings of the University of Missouri Energy Summit, April 22-23, 2009, Columbia, Missouri. p. 180-185.

Interpretive Summary: Prairie soil landscapes encompass much of the U.S. Midwest now in row crop production. Some soils within this region have been especially negatively impacted by the cultivation practices of the past 200 years, resulting in lost productivity, degraded soil, and water quality impairment. Degraded claypan or “claypan-like” soils present a scenario where land use changes in response to developing bioenergy markets could have either additional negative or positive environmental implications. The objective of this research was to explore those implications. Farmland precisely set aside from grain cropping into some other land use (such as pasture or hay), is at high risk of being put into grain crops as grain prices rise. In order to understand the relative productivity of marginal soils, we combined millions of yield map data ports collected by farmers with soil information and examined yield-soil relationships. Using this information, we were able to see that some soils were clearly much less suited for grain production and represent greater economic risk if converted from non-cultivated land to grain crops. We also found that using sensors to measure topsoil depth provides an important indicator of soil quality and also shows what portions of fields have historically lost topsoil and contributed most to water quality impairment. These areas should be high-priority areas for targeting conservation practices and should be low-priority land for grain crops. Perennial grass yields are likely to be less variable than grain yields, both year-to-year and within fields, primarily because of greater resistance to drought. Grass production systems also provide ecosystem services not obtained from annual grain crops. These ecosystem services are reduced erosion (because of the year-long ground cover protecting the soil), greater storage of soil carbon, and reduced fertilizer and herbicide inputs which in turn reduce non-point source pollution. From this, we propose that reliable maps of productivity and environmental risk are needed for these soils to help farmers weigh implications of current and future management. This will lead to more long-term investments in sustainable practices and conservation on the farm that will benefit farmers and the general public.

Technical Abstract: Prairie soil landscapes encompass over 16 million acres in Missouri and surrounding states. Much of this area has been degraded by erosion but is still used for grain production. Erosion has caused variable topsoil depth within fields which in turn has resulted in greater within-field variability of crop yield, magnified the drought-prone nature of these soils, and lowered the overall soil productivity and ecosystem function. In recent years, pressure on these sensitive soils has risen due to higher demand for grain production, in part for ethanol and biodiesel. In some areas, highly erodible fields which were historically managed as CRP and pasture are being turned into grain crop acres. Thus as new and fluctuating feed and bioenergy markets develop, land management practices will also shift, resulting in changes in soil and water quality of watersheds. This presentation will explore the likely environmental implications of different types of bioenergy production on the soil resource. Further, the positive benefits of potential changes in land use will be in explored. For example, one alternative for sensitive soils is production of perennial grass as a feedstock for coal co-burning plants and for potential future use in cellulosic ethanol production. Perennial grass yields are likely to be less variable than grain yields, both year-to-year and within fields, primarily because of greater resistance to drought. Grass production systems also provide environmental services not obtained from annual grain crops. We will also discuss our work on developing ways to target the most appropriate places in the landscape for grain or perennial production so as to enhance ecosystem services and improve soil and water quality.