Nitrogen mineralization dynamics of meat bone meal and cattle manure as affected by the application of softwood chips biochar in soil

Authors

• Priit Tammeorg Department of Agricultural Sciences, University of Helsinki, Latokartanonkaari 5, FIN-00014, Helsinki, Finland
• Tero Brandstaka Department of Agricultural Sciences, University of Helsinki, Latokartanonkaari 5, FIN-00014, Helsinki, Finland
• Asko Simojoki Department of Food and Environmental Sciences, University of Helsinki, Latokartanonkaari 11, FIN-00014, Helsinki, Finland
• Juha Helenius Department of Agricultural Sciences, University of Helsinki, Latokartanonkaari 5, FIN-00014, Helsinki, Finland

DOI: https://doi.org/10.33354/smst.75646

Keywords:

ammonium, biochar, carbon sequestration, nitrate, nitrogen immobilization, organic fertilizers

Abstract

We studied the impact of added biochar on the N mineralization dynamics of two organic fertilizers by incubating sandy loam soil for 133 days in controlled conditions. Biochar made from softwood chips was added to soil at 0, 4.6, 9.1 and 13.6 g kg^-1 soil DM either alone, or in combination with meat bone meal (MBM) and composted cattle manure (CCM) fertilizers. Soil mineral N concentration was determined on days 0, 14, 28, 56, 84 and 133.
Net N mineralization in MBM treatment was much larger than in CCM and unfertilized treatments. Constant soil moisture during the incubation provided suitable aerobic soil conditions for nitrification: after day 14, soil mineral N was dominated by nitrate in all treatments. Biochar additions decreased the mineral N concentrations in all treatments, probably because of immobilization by microbes. In unfertilized soil, the immobilisation by biochar increased steadily with application rate and time, but in MBM and CCM it started to decrease or level off after two months, possibly due to the turnover of microbial biomass.