%0 Journal Article
%T A Review of Biochar and Soil Nitrogen Dynamics
%A Tim J. Clough
%A Leo M. Condron
%A Claudia Kammann
%A Christoph M¨¹ller
%J Agronomy
%D 2013
%I MDPI AG
%R 10.3390/agronomy3020275
%X Interest in biochar stems from its potential agronomic benefits and carbon sequestration ability. Biochar application alters soil nitrogen (N) dynamics. This review establishes emerging trends and gaps in biochar-N research. Biochar adsorption of NO 3 £¿, up to 0.6 mg g £¿1 biochar, occurs at pyrolysis temperatures >600 ¡ãC with amounts adsorbed dependent on feedstock and NO 3 £¿ concentration. Biochar NH 4 + adsorption depends on feedstock, but no pyrolysis temperature trend is apparent. Long-term practical effectiveness of inorganic-N adsorption, as a NO 3 £¿ leaching mitigation option, requires further study. Biochar adsorption of ammonia (NH 3) decreases NH 3 and NO 3 £¿ losses during composting and after manure applications, and offers a mechanism for developing slow release fertilisers. Reductions in NH 3 loss vary with N source and biochar characteristics. Manure derived biochars have a role as N fertilizers. Increasing pyrolysis temperatures, during biochar manufacture from manures and biosolids, results in biochars with decreasing hydrolysable organic N and increasing aromatic and heterocyclic structures. The short- and long-term implications of biochar on N immobilisation and mineralization are specific to individual soil-biochar combinations and further systematic studies are required to predict agronomic and N cycling responses. Most nitrous oxide (N 2O) studies measuring nitrous oxide (N 2O) were short-term in nature and found emission reductions, but long-term studies are lacking, as is mechanistic understanding of reductions. Stable N isotopes have a role in elucidating biochar-N-soil dynamics. There remains a dearth of information regarding effects of biochar and soil biota on N cycling. Biochar has potential within agroecosystems to be an N input, and a mitigation agent for environmentally detrimental N losses. Future research needs to systematically understand biochar-N interactions over the long term.
%K biochar
%K immobilization
%K mineralization
%K nitrate leaching
%K nitrogen
%K nitrous oxide
%K ammonia volatilisation
%U http://www.mdpi.com/2073-4395/3/2/275