Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 8/1/2008
Publication Date: 5/12/2009
Citation: Singer, J.W., Franzluebbers, A.J., Karlen, D.L. 2009. Grass-Based Farming Systems: Soil Conservation and Environmental Quality. In: Wedin, W.F., Fales, S., editors. Grasslands: Quietness and Strength for a New American Agriculture. Madison, WI: ASA. p. 121-136.
Technical Abstract: Continuous production of the same crop often declines in yield for a variety of reasons, even with sufficient nutrient inputs. Consequently, the basis for a productive agricultural system should utilize natural processes to supply and cycle nutrients, control pest populations, and maintain the checks and balances within the agroecosystem. For centuries, farmers relied on crop rotation to maintain or enhance crop yield. Crop selection and sequence can have a profound effect on the environment and farm profitability. Using grasses and legumes in rotation with summer annual or winter annual row crops can supply nutrients to subsequent crops that can decrease the need for purchased inputs. Perennial forage crops protect the soil from wind and water erosion and use nutrients more efficiently than row crops that are usually only growing during a fraction of the growing season. Using perennials to establish permanent grasslands on highly erodible soil can eliminate almost all soil erosion. Crop rotations including perennial forages usually have soils with higher organic matter because continuous root formation, growth, and death by perennial crops contributes new carbon to the soil organic matter pool. Furthermore, land in perennial forages is not tilled, which further decreases soil organic matter. Organic matter inputs help increase the soil water holding capacity that can help to maintain crop growth during periods with below-average rainfall. In spite of these benefits, production of perennial forages declined during the 20th century. Reasons for this decline include the development of pesticides, the expansion of fertilizer manufacturing, and changing rations for ruminants, the primary consumers of forages. External inputs for crop production substitute for the ecological role crop rotation provides by breaking pest cycles and using forages to supply nitrogen to subsequent crops. The environmental effect of this paradigm shift has resulted in policy to regulate, research, and promote environmental stewardship. It remains unclear how emerging and future markets for agricultural products will impact the environment. This chapter reviews the historical role of grasslands in U.S. agriculture and potential future roles.