Title

The Effects of Biochar Age and Concentration on Soil Retention of Phosphorus and Infiltration Rate

Author(s) Information

Emilie Schneider, California Polytechnic State University, San Luis ObispoFollow

College - Author 1

College of Agriculture, Food and Environmental Sciences

Department - Author 1

Natural Resources Management and Environmental Sciences Department

Degree Name - Author 1

BS in Soil Science

Date

6-2012

Primary Advisor

Ben Burgoa

Abstract/Summary

Changes in land use and land management practices are regarded as one of the main factors in altering the hydrogeological system, causing changes in runoff, surface supply yields, and the quality of receiving water (Tong and Chen, 2002). Phosphorus is a significant contributor to accelerated eutrophication of fresh water and is largely sourced from agricultural runoff (Sharpley et al., 1994). The dominant processes controlling solution composition in agricultural soils are primarily ‘chemical’ for P (i.e. adsorption/desorption and dissolution/precipitation) (Edwards and Withers, 1998). Biochar has chemical characteristics that have the potential to adsorb P or influence precipitation of P insoluble pools (DeLuca et al., 2009). However, there is limited knowledge about changes in this behavior in soil over time. To determine the effects of biochar on P adsorption and percolation rate, soil columns containing a sandy loam were amended with 0, 1, 2, and 5% (wt/wt) biochar and incubated at field capacity for zero and nine months. Columns were leached with four pore volumes of a 5ppm P solution (Burgoa, 2011). Phosphorus concentration in the leachate was determined using an ICP-AES. Aging of biochar for nine months resulted in an insignificant increase of phosphorus retention in the soil columns. The highest increase in P retention was observed in the columns amended with 1% (wt/wt) biochar at time zero. Potential absorption capacity of biochar and other chemical influences that affect P in the soil environment seem to improve with time. Further aging of biochar would likely result in a significant increase in P adsorption capacity in soil, due to abundant transformations of surface chemistry and encouraged bond formations. Percolation rate was found to significantly increase with increased biochar addition and increased aging time had little effect. Increased concentration of Biochar amendment of soil may help mitigate the negative effects of agricultural land use and water quality of the nearby hydrogeological system.

URL: https://digitalcommons.calpoly.edu/nrmsp/22