This Thesis does make mention of the potential for biochar as a denitrifier tool in NZ. You can download the full document as a PDF from the linked title..
THE INFLUENCE OF SOIL PARAMETERS AND DENITRIFIERS ON N2O EMISSIONS IN NEW ZEALAND DAIRY-GRAZED PASTURE SOILS
A thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Massey University Palmerston North New Zealand
Page 75: “One of the possible strategies to mitigate denitrification in soil could be the application of biochar. It has been observed that biochar application facilitates the reduction of N2O to N2 by both its liming effect and by enhancing the electron availability to denitrifiers, which helps completing the denitrification process to emit N2 as the end product (Cayuela et al., 2013). With biochar application, decreases in N2O emission by 10% to 90% have been observed in 14 different agricultural soils.
A set of management practices is needed that could either lower the N2O emission from soil or increase the N2O reduction to N2 . Management practices such as the application of crop residue, liming, increasing Cu availability, high SWC, biochar application, may enhance N2O reduction to N2. Higher N2O production from some soils may be due to its poor capacity of reduce N2O to N2.”
Page 230: “In this current study, Dicyandiamide (DCD), one of the most commonly used nitrification inhibitor, was tested for its impact on denitrification. Future work could look into changes in denitrifier community abundance, total denitrification, and, more importantly, into N 2 O and N 2 productions (employing direct gas measurement technique) in New Zealand pasture soils using other mitigation methods such as the addition of organic matter, liming, Cu addition, and biochar application.”
Page 237: References
Case, S.D.C., Whitaker, J., McNamara, N.P., Reay, D.S., 2007. The effect of biochar addition on N2O and CO2 emissions from a sandy loam soil – The role of soil aeration. Soil Biology and Biochemistry 51, 125-134.
Cayuela, M.L., Sánchez-Monedero, M.A., Roig, A., Hanley, K., Enders, A., Lehmann, J., 2013. Biochar and denitrification in soils: when, how much and why does biochar reduce N 2 O emissions? Scientific Reports 3, Article No. 1732.