Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (FOC), remains a major constraint to global banana (Musa spp.) production, especially in tropical regions. Although soil conditions are known to modulate disease expression, the specific physicochemical drivers of FOC prevalence under field conditions are not well understood. This study investigated the relationships between soil properties and the Fusarium wilt incidence across 47 banana farms on Hainan Island, China, a tropical region dominated by highly weathered tropical soil (latosols). The disease incidence (%PDI) and FOC abundance were quantified, alongside key soil parameters, including the pH, organic carbon, cation exchange capacity, and macro- and micronutrient availability. The soils were predominantly acidic (mean pH 4.93), with low levels of organic carbon and exchangeable calcium (Ca) and elevated levels of available phosphorus (P), potassium (K), and magnesium (Mg). The Fusarium wilt incidence ranged from 1% to 78%, with significantly higher levels observed in younger plantations (<5 years old). Statistical analyses revealed strong negative correlations between the PDI and the soil pH, exchangeable Ca and Mg, and available K. Principal component analysis further confirmed the suppressive role of the pH and base cations in the disease dynamics. Farms older than five years exhibited better soil fertility indices and lower disease pressure, suggesting a temporal improvement in soil-mediated disease suppression. These findings underscore the critical role of soil acidification and nutrient imbalances, particularly Ca, Mg, and K deficiencies, in promoting FOC pathogenicity. Enhancing soil health offers a promising and sustainable strategy for managing Fusarium wilt in tropical banana production systems.

Reducing fertilizer doses under sustainable agricultural management is possible by increasing nutrient utilization efficiency, which will decrease crop production costs and boost economic return. Soil amendments known as water retention agents (WRAs) are added to the soil to enhance crop growth conditions. We hypothesize that the addition of WRAs may support the soil-retaining nutrients given through fertilization and prevent them from leaching into tropical soils characterized by severe rainfall due to WRAs’ exceptional capacities to absorb and store water. Mango trees (Mangifera indica L. cv Tainong No. 1) aged 18 years were fertilized with 100% or 80% of the recommended doses of nitrogen (N), phosphorus (P), and potassium (K). The experimental design included three treatments, i.e., complete recommended doses of N, P, and K (CRF), 80% of the complete recommended doses (RRF), and water-retaining agent (40 kg ha⁻¹) + 80% of the complete recommended doses (WRARRF). Reducing the fertilization doses by 20% for mango trees in the studied tropical soil significantly (p < 0.05) minimized the nutrient availability in the soil compared to the complete fertilization doses. WRARRF compensated for the nutrient reduction by increasing the availability of N, P, and K. The addition of WRARR increased N, P, and K in mango leaf by 11%, 4%, and 7% in the first year and by 11%, 6%, and 7% in the second year, respectively, compared to CRF. The addition of WRARR increased the partial fertilizer productivity (PFP) value by 36% and 41% in the first and second years, respectively. The highest mango fruit output was achieved by the addition of WRARRF, which resulted in increases in mango fruit yield of 11.9% and 16.5% in the first and second years, respectively, compared to RRF. Fruit quality traits showed the descending order: WRARRF > RRF > CRF. WRARRF produced the maximum economic benefit (USD 7372 per hectare) compared to CRF and RRF. The polyacrylamide/attapulgite water-retaining agent exhibited remarkable improvement in mango fruit yield and economic profit by regulating the release of nutrients in tropical soils. Water-retaining agents are an effective strategy for overcoming the extensive fertilization used in mango orchards, which has resulted in numerous environmental contaminations and the inefficient use of fertilizers.