Burton C. English, University of Tennessee
Daniel F. Mooney, University of Wisconsin
James A. Larson, University of Tennessee
Don Tyler, University of Tennessee
Dustin K. Toliver, Huvepharma, Inc
Today’s economy is primarily based on the use of fossil fuel, but the potential of renewable alternatives, such as bioenergy, is being evaluated. The rationale for this interest centers on climate change, national security and rural development. The United States has increased its production capacity of ethanol, a bioenergy alternative to gasoline, from 1.7 billion gallons in 2000 to 15.5 billion gallons at the beginning of 2017 [70]. Current legislation requires production to increase into the future, and this ethanol will mostly be produced from cellulose [67]. Thus, the use of crop residues for bioenergy and the use of dedicated bioenergy crops are likely to play an important role in the management of conservation tillage systems in the Southeast.
An analysis by English et al. [19] found that 100 million acres of dedicated energy crops would be needed to replace 25 percent of the nation’s energy by 2025. While production is projected to occur throughout the United States, the mid-southern states (Kentucky, Tennessee, Alabama, Mississippi, Georgia and the Carolinas) would produce the bulk of these feedstocks. While dedicated energy crops are one source of cellulose, crop residues may play a role as an energy feedstock as well. In a joint study by the USDA and Department of Energy (DOE) on potential biomass feedstocks, annual production of 75 million dry tons of corn stover and 11 million dry tons of wheat straw were identified as a possible bioenergy feedstock [53].
This chapter examines the potential role of harvesting crop residues and producing dedicated bioenergy crops in conservation tillage systems. When crop residues such as corn stover are left on the soil surface, they provide a number of benefits such as reduced erosion, increased soil organic carbon, improved soil tilth, improved water retention and the recycling of nutrients back to the soil [32]. The benefits of conservation tillage systems are in part based on residues on the soil surface, and removal of the residues would reduce these benefits. Harvesting crop residues could provide another income stream for farmers, but it must be done sustainably and should be weighed against any loss in soil conservation benefits. The other option, planting a dedicated bioenergy crop, may enhance conservation tillage systems. Switchgrass, a perennial bioenergy crop, is well-suited from an agronomic and economic perspective to being planted on marginal cropland. Switchgrass can help reduce erosion, increase soil organic carbon, reduce nutrient leaching and restore soil health. When evaluating switchgrass as a bioenergy feedstock, consider the costs and constraints it may impose on the current cropping system. The remainder of this chapter provides insight on the removal of crop residues and conservation concerns, and includes an in-depth discussion of growing switchgrass as a dedicated bioenergy crop.
Download the tables from Chapter 16.
Table of Contents
- Author and Contributor List
- Foreword
- Chapter 1: Introduction to Conservation Tillage Systems
- Chapter 2: Conservation Tillage Systems: History, the Future and Benefits
- Chapter 3: Benefits of Increasing Soil Organic Matter
- Chapter 4: The Calendar: Management Tasks by Season
- Chapter 5: Cover Crop Management
- Chapter 6: In-Row Subsoiling to Disrupt Soil Compaction
- Chapter 7: Cash Crop Selection and Rotation
- Chapter 8: Sod, Grazing and Row-Crop Rotation: Enhancing Conservation Tillage
- Chapter 9: Planting in Cover Crop Residue
- Chapter 10: Soil Fertility Management
- Chapter 11: Weed Management and Herbicide Resistance
- Chapter 12: Plant-Parasitic Nematode Management
- Chapter 13: Insect Pest Management
- Chapter 14: Water Management
- Chapter 15: Conservation Economics: Budgeting, Cover Crops and Government Programs
- Chapter 16: Biofuel Feedstock Production: Crop Residues and Dedicated Bioenergy Crops
- Chapter 17: Tennessee Valley and Sandstone Plateau Region Case Studies
- Chapter 18: Southern Coastal Plain and Atlantic Coast Flatwoods Case Studies
- Cash Crop Selection and Crop Rotations
- Specific Management Considerations
- Case Study Farms
- Producer Experiences
- Transition to No-Till
- Changes in Natural Resources
- Changes in Agricultural Production
- Specialty Crops
- Why Change to No-Till?
- Supporting Technologies and Practices
- The Future
- Research Case Study
- Summary
- Chapter 19: Alabama and Mississippi Blackland Prairie Case Studies
- Chapter 20: Southern Piedmont Case Studies
- Appendix
- Glossary
- References