Micronutrients, particularly boron (B), iron (Fe), manganese (Mn), and zinc (Zn), are pivotal for cotton (Gossypium spp.) growth, reproductive success, and fiber quality. However, their critical roles are often overlooked in fertility programs focused primarily on macronutrients. This review synthesizes recent advances in the physiological, molecular, and agronomic understanding of B, Fe, Mn, and Zn in cotton production. The overarching goal is to elucidate their impact on cotton nutrient use efficiency (NUE). Drawing from the peer-reviewed literature, we highlight how these micronutrients regulate essential processes, including photosynthesis, cell wall integrity, hormone signaling, and stress remediation. These processes directly influence root development, boll retention, and fiber quality. As a result, deficiencies in these micronutrients contribute to significant yield gaps even when macronutrients are sufficiently supplied. Key genes, including Boron Transporter 1 (BOR1), Iron-Regulated Transporter 1 (IRT1), Natural Resistance-Associated Macrophage Protein 1 (NRAMP1), Zinc-Regulated Transporter/Iron-Regulated Transporter-like Protein (ZIP), and Gossypium hirsutum Zinc/Iron-regulated transporter-like Protein 3 (GhZIP3), are crucial for mediating micronutrient uptake and homeostasis. These genes can be leveraged in breeding for high-yielding, nutrient-efficient cotton varieties. In addition to molecular hacks, advanced phenotyping technologies, such as unmanned aerial vehicles (UAVs) and single-cell RNA sequencing (scRNA-seq; a technology that measures gene expression at single-cell level, enabling the high-resolution analysis of cellular diversity and the identification of rare cell types), provide novel avenues for identifying nutrient-efficient genotypes and elucidating regulatory networks. Future research directions should include leveraging microRNAs, CRISPR-based gene editing, and precision nutrient management to enhance the use efficiency of B, Fe, Mn, and Zn. These approaches are essential for addressing environmental challenges and closing persistent yield gaps within sustainable cotton production systems.

Kamuli District offers an opportunity to understand pedology and cropping decisions in an area that has been underdocumented. Broad, flat summits and narrow convex shoulders are composed of residuum formed from Precambrian granite. Valleys mirror the summits, that is, broad flats composed of alluvium that are rimmed by narrow concave toeslopes. The alluvial landscape is a mix of Holocene terraces and modern floodplains. Gentle, linear backslopes gently merge into footslopes connecting the summits and valleys. These positions are composed of residuum‐derived colluvium. These geologic and geomorphic differences create a systematic soil landscape pattern with Oxisols predominating on summits and shoulders, Ultisols predominating on the backslopes and footslopes, and Alfisols predominating across the valleys. The backslopes are more intensively cultivated compared to the summits and valleys. A comparison between cultivated and uncultivated areas revealed a dynamic relationship dependent on landscape position and human impacts. Critical human impacts include upland erosion, declining soil organic matter content, available phosphorus, total nitrogen, and exchangeable bases. Each of these appears to be gradually diminishing soil function, which has dire implications for future food security in Kamuli District.

Based on 5 years of integrated pedological work in Kamuli District, this study examines how farmers in three villages understand and classify soils. The farmers' knowledge was documented through a participatory approach that included discussions, soil mapping, subsequent field reconnaissance, and 23 pedon descriptions. Based on comparable needs and landscapes, farmers across three villages classified the soils into four groups: Lirugavu, Lubalebale, Mukyanga , and Mutaala . These corresponded to six USDA Soil Taxonomy suborders, Aqualfs, Aquolls, Ustalfs, Ustults, Ustox, and Ustipsamments. Farmers demonstrated spatial awareness through the soil mapping exercise, in which soils were associated with specific landscape positions. A farmer-based ranking in terms of soil productivity aligned with Corn Suitability Rating (CSR2) values, with Lirugavu and Lubalebale as the most and least productive, respectively. The farmer-based soil groupings/ classification distinguished soils by depth of mollic colors, clay content, organic matter (SOM), total nitrogen (N), and cation exchange capacity (CEC). The ability of the soil groupings to discern vertical variation, that is, significant differences from 0–15 cm to 15–30 cm depth layers, was captured only for SOM and N in Lirugavu . Soil Taxonomy suborders captured a wider range of chemical properties and more consistent vertical differentiation. These findings highlight the differences in epistemology but with potential for complementarity between farmer-based and scientific classification systems, leading to integrated approaches to soil assessment and management.

This study identifies the parent material (PM) and examines cation exchange capacity (CEC) across the Busoga catena. In 2022 and 2023, we described 32 pedons and collected 147 samples. Laboratory analyses were particle size analysis, organic carbon (OC) content, pH, and CEC. Results indicate that the Busoga catena occurs across a Precambrian granitic residuum plateau that is dissected by Holocene and modern aged nearly level alluvial valleys filled with sediment from the Nile River back flooding and local stream sediment. Connecting the residual plateau uplands with the alluvial valleys are colluvial backslopes. Alfisols and Oxisols dominated the residual and colluvial PM. In contrast, Entisols, Mollisols, Ultisols, and Vertisols dominated the alluvial PM in the lowland landscape positions. Pedotransfer analysis revealed CEC to be a function of OC, clay, and pH. The best‐fit multiple linear relationship was CEC predicted = 1.77 pH + 0.08% clay + 4.76% OC, n = 44, Adj. ( R ² )   = 0.94**. In turn, clay and OC content could be explained using PM and landscape position.

Plinthite is a major pedogenic feature in the Kamuli catena, posing significant challenges for agricultural land use. This study investigates the morphological expression and mineralogical insights into plinthite within the soil-landscape of Kamuli District. Soil characterization involved detailed field morphological descriptions along the Kamuli catena followed by laboratory characterization of major soil properties. Plinthite mineralogy was determined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphology of plinthic soils varied along the catena with summit pedons exhibiting shallow plinthic horizons and backslope pedons showing comparatively deeper occurrences. The lowlands underlain by alluvium of the Holocene lacked plinthite. Mineralogical analysis of ten plinthite samples identified two distinct assemblages. Group 1 (quartz, kaolinite, hematite, goethite, manganite) represents a highly weathered endmember associated with stable summits. Group 2 (muscovite, kaolinite, hematite, goethite, manganite), with elevated K, Mg, Na, and Ca in SEM-EDS, indicating they are recent compared to Group 1. This elemental composition directly reflects the signature of the parent material preserved within Group 2 samples. Plinthite in the Kamuli catena is a relict feature, whose formation is tied to past drainage regimes. Its multi-stage history is recorded in the two mineralogical groups separated by hundreds of thousands of years of landscape evolution. Group 1 represents plinthite from the deeply weathered African Surface. Group 2 is later formed on the substrate exposed by stripping along the Victoria Nile.

The Southern Highland Zone constitutes Tanzania’s principal agricultural belt, accounting for approximately fifty percent of the nation’s food supply. Most of the soil of the region’s agroecozones is strongly acidic, causing poor crop yields and inefficient fertilizer utilization. Phosphorus (P) sorption characteristics were investigated across acidic soils to assess their implications for P availability and soil fertility management. Surface soil samples (0-30) cm sampling depth obtained from the unlimed and limed plots of study sites were analyzed for P-sorption dynamics. The P-sorption data were fitted to the Freundlich isotherms to estimate sorption capacities and heterogeneity of adsorption sites. The results on Freundlich P-adsorption capacity (K _F ) in mg/Kg of soil recorded 1433.0±131.0 and 1396.6±141.7, 971.0±222.4 and 883.3±269.5, 1644.2±26.3 and 1595.7±43.0, 1055.4±62.3 and 1001.9±105.5; standard phosphorus requirement (SPR) in mg/Kg of soil 223.0±5.8 and 205.1±13.2, 122.8±17.7 and 104.7±18.4, 235.4±5.0 and 221.6±3.0, 113.3±19.0 and 97.9±13 for unlimed and limed experimental plots at Mbimba, Kifyulilo, Igeri and Uyole respectively. These results revealed strong P adsorption trends. Liming substantially reduced P-sorption capacities and heterogeneity of adsorption sites in the soil, increased equilibrium P concentration, indicating improved P availability through charge neutralization and reduced activity of iron (Fe) and aluminum (Al) sesquioxides. The SPR computed values indicated that the external addition of phosphorus according to national recommendations provide suboptimal fertilization of phosphorus in the Southern Highlands of Tanzania. These findings highlight that managing soil acidity through liming is essential to minimize P-adsorption and enhance fertilizer use efficiency in low-P tropical soils.