Short-term dynamics of carbon and nitrogen using compost, compost-biochar mixture and organo-mineral biochar

This study aims to examine the effects of different organic treatments including compost (generated from cattle hide waste and plant material), compost mixed with biochar (compost+biochar) and a new formulation of organo-mineral biochar (produced by mixing biochar with clay, minerals and chicken manure) on carbon (C) nitrogen (N) cycling. We used compost at the rate of 20 t ha−1, compost 20 t ha−1 mixed with 10 t ha−1 biochar (compost+biochar) and organo-mineral bio-char which also contained 10 t ha−1 biochar. Control samples received neither of the treatments. Compost and compost+biochar increased NH4+-N concentrations for a short time, mainly due to the release of their NH4+-N content. Compost + biochar did not alter N cycling of the compost significantly but did significantly increase CO2 emission compared to control. Compost significantly increased N2O emission compared to control. Compost+ biochar did not significantly change N supply and also did not decrease CO2 and N2O emissions compared to compost, suggesting probably higher rates of biochar may be required to be added to the compost to significantly affect compost-induced C and N alteration. The organo-mineral biochar had no effect on N cycling and did not stimulate CO2 and N2 O emission compared to the control. However, organo-mineral biochar maintained significantly higher dissolved organic carbon (DOC) than compost and compost+biochar from after day 14 to the end of the incubation. Biochar used in organo-mineral biochar had increased organic C adsorption which may become available eventually. However, increased DOC in organo-mineral bio-char probably originated from both biochar and chicken manure which was not differentiated in this experiment. Hence, in our experiment, compost, compost+biochar and organo-mineral biochar affected C and N cycling differently mainly due to their different content.