|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., Karlen, D.L., Wang, B., Horton, R. 2010b. Biochar Impact on Nutrient Leaching from a Midwestern Agricultural Soil. Geoderma. 158:436-442. Interpretive Summary: Charcoal (a.k.a., biochar) is a bi-product of the pyrolysis platform for producing bioenergy from crop and forestry residues. Application of biochar to tropical soils has been shown to enhance soil quality and decrease leaching of nutrients. We determined that biochar applications on a typical Midwestern agricultural soil substantially reduced the leaching of several nutrients following the application of swine manure to the soil. Nitrogen leaching was reduced by 11% and phosphorous leaching was reduced by up to 69%. The soil biochar applications also reduced leaching of calcium, magnesium, sodium, potassium, and silicon. By helping to keep these nutrients in the soil, biochar helps to improve both nutrient-use efficiency and reduces the risk that the nutrients will contaminate surface and ground water. This study will help scientists to 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: Application of biochar to highly weathered tropical soils has been shown to enhance soil quality and decrease leaching of nutrients. Little, however, is known about the effects of biochar applications on temperate region soils. Our objective was to quantify the impact of biochar on leaching of plant nutrients following application of swine manure to a typical Midwestern agricultural soil in a laboratory experiment. Repacked soil columns containing 0, 5, 10, and 20 g-biochar kg-1-soil, with and without 5 g kg-1 of dried swine manure were leached weekly for 45 weeks. Measurements showed a significant decrease in the amount of N, P, Mg, and Si that leached from the manure amended columns as biochar rates increased, even though the biochar itself added substantial amounts of these nutrients to the columns. With the manure amendment, total N and total dissolved P leaching were reduced by 11% and 69%, respectively, with 20 g kg-1 biochar. By-pass-flow, indicated by spikes in nutrient leaching, occurred during the first leaching event after manure application in the control treatment, but was not observed for any of the biochar amended columns. These laboratory results indicate that addition of biochar to a Midwestern agricultural soil can substantially reduce nutrient leaching by increasing the soils’ capacity to adsorb both inorganic nutrients and those associated with soluble organic compounds.