|Karlen, Douglas - Doug|
Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2010
Publication Date: 9/24/2010
Citation: Laird, D.A., Fleming, P.D., Davis, D.D., Horton, R., Wang, B., Karlen, D.L. 2010a. Impact of Biochar Amendments on the Quality of a Typical Midwestern Agricultural Soil. Soil Science Society of America Journal. 158:443-449. Interpretive Summary: Charcoal (a.k.a., biochar) is a bi-product of the pyrolysis platform for producing bioenergy from crop and forestry residues. We determined that biochar applications on a typical Midwestern agricultural soil can increase the amount of organic carbon and nitrogen in the soil, the ability of soil to hold both water and plant nutrients, act as a liming agent, and reduce soil compaction. These improvements in soil quality suggest that biochar amendments may help compensate for some of the adverse effects on soils of harvesting biomass for bioenergy production. This study will help scientists better understand the effects of biochar on soils and will provide information for policy makers and action agencies on the effects of soil biochar applications.
Technical Abstract: Biochar, a co-product of thermochemical conversion of lignocellulosic materials into advanced biofuels, may be used as a soil amendment to enhance the sustainability of harvesting biomass. We investigated the impact of biochar amendments (0, 5, 10, and 20 g-biochar kg-1 soil) on the quality of a Clarion soil (Mesic Typic Hapludolls), collected (0-15 cm) in Boone County, Iowa. Repacked soil columns were incubated for 500 days at 25°C and 80% relative humidity. On week 12, 5 g of dried and ground swine manure were incorporated into the upper 3 cm of soil for half of the columns. Once each week, all columns were leached with 200 mL of 0.001 M CaCl2. Soil bulk density increased with time for all columns but was significantly lower for biochar amended soils relative to the un-amended soils. The biochar amended soils retained more water at gravity drained equilibrium (up to 15%), had greater water retention at -1 and -5 bars soil water matric potential, (13 and 10% greater, respectively), larger specific surface areas (up to 18%), higher cation exchange capacities (up to 20%), and pH values (up to 1 pH unit) relative to the un-amended controls. No effect of biochar on saturated hydraulic conductivity was detected. The biochar amendments significantly increased total N (up to 7%), organic C (up to 69%), and Mehlich III extractable P, K, Mg and Ca but had no effect on Mehlich III extractable S, Cu, and Zn. The results indicate that biochar amendments have the potential to substantially improve the quality and fertility status of Midwestern agricultural soils.