Impact of Biochar on Nitrogen Cycling: Impact of Oxidation and Application to Filter Strips

Biochar has been shown to have the ability to affect nitrogen cycling in soils. In this study, we investigated the impact of adding biochar to filter strip plots to understand the impact on nitrogen leaching, particularly in the form of nitrate. In addition, we examined additions of biochar to soil columns to determine the mechanism for reductions in leaching and to assess the impacts to nitrous oxide emissions.  

What did we do?

Figure 1: Filter strip plots with vegetation receiving silage runoff with collection of surface and subsurface water samples

We conducted three studies to investigate the impact of biochar to nitrogen cycling. First, we developed filter strip plots where we added biochar to the soil matrix in three of six plots. We then applied bunker silage storage runoff ( containing nitrogen) to the plots and determined the forms and quantities of nitrogen leaching through the soil profile. Second, we oxidized biochar and completed sorption studies to determine if oxidation of biochar plays a role in nitrate sorption. Third, we conducted soil column experiments to determine if biochar impacted mineralization rates, nitrification and/or denitrification in soil systems when synthetic wastewater containing nitrogen was applied.

What have we learned?

We have found that biochar does impact nitrogen leaching. When added to filter strip plots, it reduced total nitrogen and nitrate leaching. In addition, oxidation of biochar was found to have an impact to nitrate sorption. Finally, when biochar is applied to soil columns it not only reduces nitrate leaching but also reduces nitrous oxide emissions.

Future plans

We plan to further investigate biochar applications to reduce nitrogen losses to the environment.


Rebecca A. Larson, Associate Professor, Biological Systems Engineering, University of Wisconsin-Madison,

Joseph Sanford, Biological Systems Engineering, University of Wisconsin-Madison


This material is based on work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2015-67019-23573 and 2017-67003-26055.



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