IMPROVING SOILS AND THEIR MANAGEMENT FOR MORE EFFICIENT WATER USE IN ENVIRONMENTALLY SUSTAINABLE AGRICULTURE
Location: Coastal Plain Soil, Water and Plant Conservation Research
Title: Selection and use of designer biochars to improve characteristics of southeastern USA Coastal Plain degraded soils
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 13, 2011
Publication Date: September 12, 2012
Citation: Novak, J.M., Busscher, W.J. 2012. Selection and use of designer biochars to improve characteristics of southeastern USA Coastal Plain degraded soils. In: Lee, J.W., editor. Advanced Biofuels and Bioproducts. New York:NY: Springer. p. 69-96.
Interpretive Summary: Sandy soils of the southeastern USA Coastal Plains have a long history of agricultural production. They were initially cultivated by Paleo-Americans and then by early European settlers who, in time, intensively farmed the soils which eventually led to soil degradation. Because soils are sandy, degraded, and highly weathered, they require intensive management to be productive. They have low fertility, poor water storage, and poorly-aggregated, hard subsurface layers that limit root growth. The result of all this is that, even though rainfall is not poor, more often than not, crops experience yield-reducing drought. To remedy the poor growing conditions, soils are annually deep tilled to shatter the hard layer and promote root growth; but soil loosening is temporary and soils re-compact. Soils can be improved more permanently by amending them with organic matter, the most likely of which would be crop residues. However, residues do not last long in the hot wet environment. An amendment that is more resistant to change is biochar. It has lasted for hundreds of years in tropical areas and has the potential to improve soil fertility and water holding capacities. However, not just any biochar can positively amend the soil; some have properties that can be detrimental. Biochar properties depend on how they were developed, such as the original material that was charred and the temperature of the charring process. Biochars can be designed that have properties complimentary to soil problems. This chapter discusses coastal soil problems and how we can produce biochars for them that will sequester carbon, enhance fertility, and increase water holding capacities for improved crop growth and productivity.
Sandy soils in the southeastern Coastal Plain Region have a long history of agricultural production; the soils were initially cultivated by Paleo-Americans and more recently by European settlers with row crops (corn, cotton, wheat, etc.). Because these soils are sandy, they have poor tilth. Soils were derived from marine sediments deposited approximately 0.5 to 5 million years ago and are extensively weathered as a result of their age, climate, sandy textures, and poor ability to retain nutrients. Moreover, these soils have poor water storage and limited root penetration due to a poorly-aggregated, subsurface hard layer that limits root growth and leads to crop moisture stress. Annual deep tillage is used to shatter the hard layer after which natural and traffic-induced re-cementation occurs. When organic carbon in crop residues is returned to soil, it can improve fertility and physical characteristics; however, the warm and wet climate of the Coastal Plain promotes its rapid oxidation and loss. Amendments of biochar should help overcome these soil tilth challenges. When organic by-products are pyrolyzed to produce bio-oil, biochar is a by-product. Biochar may be a more appropriate soil amendment than crop residues because it is more recalcitrant and stimulates biotic and abiotic soil reactions. Research indicates that one biochar-type will not serve as a universal supplement to all soils; therefore, it may be prudent to design a biochar with physico-chemical properties that can ameliorate specific problems. There are only a few reports on designing biochars to ameliorate specific soil issues; moreover, guidelines for their selection and use are unavailable. The objectives of this study are to describe the need for remediation of physical and chemical characteristics of sandy Coastal Plain soils and to develop guidelines for the selection and use of designer biochars that can improve soil deficiencies and reduce greenhouse gas emissions.