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Agronomy 2013, 3(2), 294-312; doi:10.3390/agronomy3020294

Characterization and Mineralization Rates of Low Temperature Peanut Hull and Pine Chip Biochars

1,* , 1
1 The University of Georgia, Department of Crop and Soil Sciences, Miller Plant Sciences, Athens, GA 30602, USA 2 The University of Georgia, Department of Biological and Agricultural Engineering, Driftmier Engineering Center, Athens, GA 30602, USA
* Author to whom correspondence should be addressed.
Received: 30 November 2012 / Revised: 23 January 2013 / Accepted: 7 April 2013 / Published: 16 April 2013
(This article belongs to the Special Issue Biochar as Option for Sustainable Resource Management)
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Biochar can potentially increase soil fertility and sequester carbon by incorporating nutrients and stable black carbon into the soil; however its effect on soil nitrogen (N) and carbon (C) processes is not well understood. A defined methodology to characterize biochar is necessary to predict how specific biochars will affect C and N mineralization. We amended a Tifton soil (Fine-loamy, siliceous, thermic Plinthic Kandiudults) with peanut hull (Arachis hypogaea; PH; 2.1% N) and pine chip (Pinus taeda; PC: 0.4% N) biochar at application rates of 1% and 2% (w/w) and performed a 136-day mineralization study. A companion 24-day mineralization study amended Tifton soil with PH and PC biochar at 2% and their respective feedstocks at equal C rates. Soil C mineralization rates were monitored periodically throughout each study and total N mineralization rates were also measured. In addition, we characterized each biochar using thermogravimetric analysis with mass spectrometer (TGA-MS), proximate analysis, Fourier transform infrared spectroscopy (FTIR), and total mineral analysis to identify biochar characteristics that might correlate with mineralization properties. Limited C (<2%) mineralized from both biochars, but mineralization rates of soil amended with PH biochar were higher than PC biochar. Carbon mineralization correlated well with estimated aliphatic content determined by TGA-MS but not with volatile content indicated by proximate analysis. Nitrogen was not mineralized from either biochar, indicating that plant-based biochar should not be considered a source of N for plant growth. The N in biochar may be contained in the stable aromatic structure of the biochar, as indicated by TGA-MS, and not available to soil microbes.
Keywords: biochar; soil; mineralization; characterization; carbon; nitrogen biochar; soil; mineralization; characterization; carbon; nitrogen
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Harris, K.; Gaskin, J.; Cabrera, M.; Miller, W.; Das, K. Characterization and Mineralization Rates of Low Temperature Peanut Hull and Pine Chip Biochars. Agronomy 2013, 3, 294-312.

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