**5. Conclusions**

The study used postharvest soil samples taken from fields following maize crop five months after biochar application to compare the effect of FN and NBC on soil NO3 −–N, NH4 +–N, SOC, and TSN. It was hypothesized that greater recovery of inorganic N and SOC would be observed under NBC compared to NF following harvest of maize. Generally, results averaged over sites and years showed some advantages of applying NBC as opposed to FN where NO3 −–N, NH4 +–N, SOC, and TSN increased under the combination by 4%, 20%, 9%, and 5%, respectively. Positive impact of the combination was realized with 10 and 15 t ha−<sup>1</sup> of biochar. The SOC, NO3 −–N, and NH4 +–N increased with increase in fertilizer rates. Whereas biochar improved SOC at both sites, significant response of NO3 −–N and NH4 +–N availability to biochar application were only observed at LCB site with sandy loam soil but not at Efaw with silty clay loam. Thus, the application of biochar in combination with fertilizer-N improves N availability with the potential to increase crop N uptake on coarse textured soils compared to soils with fine texture. Therefore, given the pivotal role of C and N in soil quality, this study shows that application of a combination of biochar and inorganic N could be important in the future management of soils which are inherently poor with texture-related limitations. Since the current study did not specifically evaluate the retentive capacity of biochar, future study could estimate the actual adsorption capacity by analyzing the CEC, AEC, and base saturation of soils treated with biochar.

**Author Contributions:** Conceptualization, P.O.; methodology, P.O.; formal analysis, P.O. and L.A.; investigation, P.O.; resources, D.B.A.; writing—original draft preparation, P.O.; writing—review and editing, L.A., F.O., A.O., J.L.B.S. and D.B.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors would like to acknowledge and sincerely thank Tyler Lynch and Robert Lemings for their assistance with field work.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

