Effects of biochar produced from different feedstocks and organic fertilizers on soil properties and maize (Zea mays L.) production in the northern part of Rwanda

Abstract This study applied biochar derived from different local feedstocks and organic fertilizers (OF) on contrasting acidic soils, Andosol and Nitisol, in order to investigate their effects on selected soil properties and maize growth and yield parameters. A split plot design was employed, with treatments being factorial combinations of OF (control without OF (OF0), cow manure (OF1), chicken manure (OF2), and compost (OF3)) as a main plot factor and biochar (no biochar applied (B0), maize straw biochar (B1), eucalyptus biochar (B2), pinus biochar (B3)) as a sub-plot factor. An amelioration in soil properties was observed in treated plots compared to the control, with a general increase in soil pH, organic carbon, total N, available P, K + , Ca 2+ , cation exchange capacity and porosity, and a decrease in Na + , Al 3+ and H + , and bulk density. With both soils, biochar - OF combination resulted in better increase of the growth and yields of maize compared to the isolate use of biochar and OF. The highest maize yield (17.14% and 60.17% increase on Andosol and Nitisol, respectively) and above ground biomass (AGB) were achieved with OF2 + B2 treatment. Interactive effects of biochar and OF were significant with both soils, for K + , stem girth, AGB and maize grain yield, emphasising a synergistic effect in the integrated use of biochar and OF. Thus, using biochar-OF combination, especially OF2 + B2, could be a good practice to be recommended for farmers in order to amend the Andosol and Nitisol and enhance maize production in the northern Rwanda.