Soil Macro- and Micronutrient Variability Across Contrasting Land-Use Systems With Differing No-Till Histories in Humid Tropical Ferric Luvisols

Understanding how integrated land management systems influence soil nutrient dynamics is essential for sustaining crop production on degraded humid tropical soils. This study compared soil macro- and micronutrient status across six land-use systems established on Ferric Luvisols at the International Institute of Tropical Agriculture, Ibadan, Nigeria: conventionally managed arable land (CMA), four no-till systems with 2-, 4-, 7-, and 10-year management histories (NT2, NT4, NT7, and NT10), and adjacent natural forest land (NFL). The no-till systems differed from the conventional system not only in tillage history, but also in crop type, organic nutrient inputs, mulching, and irrigation practices. Consequently, the study was designed to evaluate integrated system-level differences rather than isolate the independent effect of no-till duration. Soil samples were collected at 0–5 and 5–10 cm depth from replicated plots and analyzed for pH, electrical conductivity, organic carbon, total nitrogen, available phosphorus, exchangeable bases, and selected micronutrients. Distinct nutrient patterns emerged among land-use systems. Relative to CMA, the longer-established no-till systems, particularly NT7 and NT10, exhibited greater soil organic carbon, cation exchange capacity, exchangeable bases, and concentrations of Zn, Mn, and Cu. These systems also showed lower estimated nutrient leaching potential, suggesting improved nutrient retention. In contrast, CMA exhibited the highest leaching potential and lower concentrations of several organic-bound nutrients. Nutrient levels in NT2 and NT4 were generally intermediate between CMA and the longer-established no-till systems. The observed differences are interpreted as the cumulative outcome of contrasting management histories, including residue retention, organic amendments, reduced soil disturbance, and perennial crop cover, rather than the effect of tillage duration alone. The findings highlight the importance of integrated conservation-oriented management systems for improving nutrient retention and soil quality in highly weathered tropical soils.