Combinations of a biofertilizer with micro-dosed chemical fertilizers increased yield of maize in a high acid saturated soil

Maize yields are usually lower for small-scale farmers relative to commercial farmers due to uncontrolled root diseases, acidic and nutrient deficient soils. Fertilizer micro-dosing is a promising strategy that has been earmarked to complement traditional fertilizer management strategies. However, this strategy is rarely known regarding its performance in maize systems in Southern Africa. The study was conducted over two seasons aiming at developing cost effective strategies on liming and fertilization to increase maize yields for farmers with low affordability and high acid saturated soils. Soil type used in this study had an acid saturation of 54% requiring 4.5 tons ha⁻¹ dolomitic lime to obtain 4 tons ha⁻¹ maize grain yields. Micro-dosing of NPK 2:3:2(34) fertilizer; superphosphate fertilizer and dolomitic lime were exploited to increase maize grain yields in a high acid saturated soil over time to cater for the farmer's affordability. A formulation of Bacillus megaterium was used as a biofertilizer. Micro-dosing of NPK 2:3:2(34) fertilizer increased maize yields by 64.6% (Season 1) and 13.6% (Season 2) when compared to the control treatment (unfertilized control) over the two seasons. Micro-dosing with superphosphate fertilizer alone significantly (P = 0.001) increased maize yield in Season 1 by 50.5% and Season 2 by 37.4% relative to the control. The combination of B. megaterium and micro-dosed NPK 2:3:2(34) fertilizer significantly (P = 0.001) increased maize yield in both seasons by 54.7% and 48.1%, respectively in comparison to the control. Whenever B. megaterium was included in the treatment combinations, there was a further increase in maize grain yield in both seasons. In all micro-dosing combinations where NPK 2:3:2(34) fertilizer and superphosphate were present, fertilizer use efficiency (FUE) were lower than micro-dosing of either NPK 2:3:2(34) fertilizer or superphosphate alone. The combination of precision placement of micro-dosed fertilizers and lime with B. megaterium may be a solution for small-scale farmers who have soils with high acid saturation.