Quantifying biochar content in biochar amended roadway soil using a two-temperature loss on ignition method
Date
2017
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Publisher
University of Delaware
Abstract
While the use of biochar in stormwater management and as a soil amendment is gaining popularity, quantification of biochar in soil is still challenging. The objective of this work was to develop a simple and inexpensive method to quantify biochar content in field soil – the two-temperature loss on ignition (LOI) method. In this approach, a biochar/soil sample is heated sequentially to three temperatures (110oC, LT and HT) and the mass loss recorded at each temperature. Using these LOI data and similar LOI measurements of biochar and soil alone, the mass fraction of biochar in a biochar/soil sample is computed. The method does not require uniform soil organic matter. This new method was tested using a biochar produced from wood pyrolyzed at high temperature (550oC) amended to a roadway filter strip. Based on LOI profiles of the soil and biochar, the two temperatures selected for this application were LT=200oC and HT=550oC. Within measurement error, estimates of biochar content from the method matched independent measurements for soils with low (0%) and high (4%, w/w) biochar mass fraction. The method also indicated significant vertical segregation of biochar at this field site. The two-temperature LOI method is applicable to conditions where the soil and biochar have significantly different LOI profiles and where the LOI profile of the biochar is temporally invariant over the duration of measurements. ☐ Keywords: Biochar, Loss on ignition, Measurement, Stormwater treatment