LAUSR

Abstract Various responses of plant growth attributes to the combined application of biochar and mineral fertilizers were reported according to trial conditions. Thus we studied the effects of biochar combined with nitrogen and phosphorous fertilizers on crop growth and yield and NUE of maize crop under alkali clay soil. Field trial during two successive seasons (2018 and 2019) was conducted to investigate the possibility of biochar addition (0, 6 and 12 Mg ha−1), as well as, P (0 and 37 kg P2O5 ha−1) and N (95, 190 and 285 kg N ha−1) fertilizations on maize and some nitrogen use efficiencies attributes. The results revealed that, biochar addition at 6 or 12 Mg ha−1 resulted in a significant reduction in plant height, stem diameter and ear length compared with the control treatment. In contrast, biochar applied recorded significant increase in both leaves area per plant, grain yield and yield attributes, as well as, grain protein content, NUE, grain-NUtE, as well as, total-NUpE compared by control treatment. Applying 190 kg N ha−1 caused significant increase in each of growth and grain yield attributes, as well as, grain-NUtE. Biochar addition by 6 or 12 Mg ha−1 combined with P (37 kg P2O5 ha−1) and N (190 or 285 kg N ha−1) application had the greater effect on increasing stem diameter, ear length, almost yield attributes, NUE, as well as, grain-NUtE. However, NUE and total-NUpE showed negative response to biochar added with N fertilizer.