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United States Department of Agriculture

Agricultural Research Service

Research Project: Management Practices to Mitigate Global Climate Change, Enhance Bio-Energy Production, Increase Soil-C Stocks & Sustain Soil Productivity...

Location: Soil Plant Nutrient Research (SPNR)

Title: Biochar and N fertilizer alters soil N dynamics and greenhouse gas fluxes from two temperate soils

Authors
item Stewart, Catherine
item Zheng, Jiyong -
item Cotrufo, M Francesca -

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 3, 2012
Publication Date: September 17, 2012
Repository URL: http://doi:10.2134/jeq2012.0019
Citation: Stewart, C.E., Zheng, J., Cotrufo, M. 2012. Biochar and N fertilizer alters soil N dynamics and greenhouse gas fluxes from two temperate soils. Journal of Environmental Quality. 41:1361-1370.

Interpretive Summary: Biochar is a high surface-area, variable-charge organic material that may improve nutrient retention and soil C sequestration but its general beneficial properties have yet to be quantified in many soil types. Biochar has the potential to increase soil water-holding capacity, cation exchange capacity (CEC) and surface sorption capacity which decrease the leaching losses of nitrate and ammonium, and reduce the emission of N2O. Despite these properties, the magnitude of soil benefits will depend on the size, quantity, and individual characteristics of both the biochar and the amended soil. We added two sizes (>250 and <250 'm) of C3-derived biochar to two C4-soils (sandy, silty-clay loam) with and without fertilizer addition, and measured over time C and N losses trough respiration and leaching, respectively. At occasional destructive harvests, the contribution of char to soil organic matter fractions, separated by size and density, is quantified, and the potential for biochar to contribute to long term soil C stabilization assessed. Data from this experiment will be reported and results discussed in the context of the potential for biochar to promote soil organic carbon sequestration.

Technical Abstract: Biochar is a high surface-area, variable-charge organic material that may improve nutrient retention and soil C sequestration but its general beneficial properties have yet to be quantified in many soil types. Biochar has the potential to increase soil water-holding capacity, cation exchange capacity (CEC) and surface sorption capacity which decreases the leaching losses of nitrate and ammonium, and reduce the emission of N2O. Despite these properties, the magnitude of soil benefits will depend on the size, quantity, and individual characteristics of both the biochar and the amended soil. In order to determine the relative contribution of biochar to: 1) nutrient retention and 2) soil C stabilization versus losses through soil respiration, we established a relatively long-term (3 years) laboratory experiment. We added two sizes (>250 and <250 'm) of C3-derived biochar to two C4-soils (sandy, silty-clay loam) with and without fertilizer addition, and measured over time C and N losses trough respiration and leaching, respectively. At occasional destructive harvests, the contribution of char to soil organic matter fractions, separated by size and density, is quantified, and the potential for biochar to contribute to long term soil C stabilization assessed. Stable C isotope mixing model is applied to partition SOC versus biochar C in the measured C pools. Data from this experiment will be reported and results discussed in the context of the potential for biochar to promote soil organic carbon sequestration.

Last Modified: 10/24/2014