EVALUATION OF RESIDUAL EFFECTS OF LAND CLEARING AND SOIL AMENDMENT TECHNIQUES ON SOIL PROPERTIES AND TOMATO PRODUCTIVITY IN OZORO, DELTA STATE, NIGERIA

Abstract

The long-term effects of land clearing and soil amendments on soil fertility and crop productivity remain underexplored in Nigeria. This study evaluated the residual influence of five land clearing methods (slash-and-burn, slash-and-mulch, mechanical ploughing, herbicide application, and manual residue packing) and five soil amendments (cattle dung, egusi-melon cover crop, NPK fertilizer, grass clippings, and sugarcane peels) on soil properties and tomato yield in Ozoro, Delta State. A split-plot randomized complete block design was carried out in 2023 and 2024, with residual effects assessed in 2025. Results showed that slash-and-mulch maintained the highest soil infiltration (82.13 mm hr⁻¹), lower bulk density (1.47 g cm⁻³), and maximum tomato fruit weight (583.73 g plant⁻¹). Slash-and-burn had negative residual impacts, with higher bulk density (1.62 g cm⁻³) and reduced yield (481.20 g plant⁻¹). Among soil amendments, sugarcane peels and cattle dung significantly improved organic matter (4.07% and 3.98%) and microbial biomass, translating into higher tomato yields (598.47 g plant⁻¹ and 583.87 g plant⁻¹). Correlation analysis confirmed positive associations between yield and soil organic matter, infiltration, potassium, microbial biomass, and ECEC. The study concludes that slash-and-mulch combined with organic amendments leaves beneficial residual effects on soil fertility and tomato yield, while slash-and-burn and sole mineral fertilizer application degrade soil quality. Adoption of residue management and organic amendments is recommended for sustainable tomato production in Nigeria.