Improving maize yield is an objective of utmost importance for food security in Uganda. In the evaluation of soil microorganisms in crop production, it is important to assess the composition and diversity of the arbuscular mycorrhizal fungi (AMF) species in different agroecosystems. AMF play an important role in improving crop growth and yield. We present a study of the morphological diversity of native AMF species associated with the rhizosphere of maize in two locations in eastern Uganda (the Amuria and Serere districts). The effects of soil chemical properties on this diversity are also assessed. AMF diversity is assessed by the morphological identification of the spores extracted from soils samples by the wet sieving method. Spores abundance, species richness, and diversity are determined. A total of 19 AMF morphotypes distributed in 7 genera (Gigaspora, Scutellospora, Glomus, Acaulospora, Archaeospora, Entrophospora, and Paraglomus) are observed. Glomus species are abundant in all sites. Spore densities are higher in Amuria than in Serere. Soil pH, CEC, and phosphorus content influence AMF distribution. Finding the species in various agroecological environments indicates that they are adapted to the environments. Maize grown in eastern Uganda is associated with a diversity of AMF that could be selected as bio-fertilizers to improve crop production.

Maize (Zea mays L.) is a critical crop for food security and economic well-being in Uganda, yet yields remain below the threshold among smallholder farmers (2–3 t/ha). This is attributed to nutrient-depleted ferralsols, as well as planting methods and land use types. Organic amendments, either alone or in combination with biochar, offer a sustainable alternative to conventional NPK fertilizers. This study compared eight treatments (Control, NPK, organic inputs alone, and organic + biochar combinations) to evaluate impacts on maize yield, soil chemical and biological properties, and economic viability for smallholder farmers. A randomized complete block design with three replications was used to measure yield, soil pH, organic matter, N, P, and K. Root colonization by arbuscular mycorrhizal fungi and soil enzyme activities (dehydrogenase, phosphatase). A cost-benefit analysis was carried out, including input costs, labor, revenue, profitability, and Benefit-Cost Ratio (BCR). The results indicate that treatments combining organic inputs with biochar (Bokashi + Biochar, Vermicompost + Biochar) and NPK delivered the highest yields (9.3–9.5 t/ha), outperforming the control (4.0 t/ha). These treatments significantly increased soil fertility indicators (organic matter, N, P, K) and microbial health. BCRs were favorable: NPK (5.7), Bokashi (1.9), Vermicompost (1.8), and combinations (≥ 1.4). Organic amendments combined with biochar achieved yields comparable to NPK under the conditions of this study, while improving soil chemical and biological properties. To support adoption by smallholders, local production of organic amendments and technical capacity must be strengthened. Graphical Abstract The alternative text for this image may have been generated using AI.