Land-use changes from natural ecosystems into managed ecosystems resulted in negative effects on soil properties. The main objective of this study was to determine the influence of land-use system and soil depth on some selected soil properties in Akure, Nigeria. The land-use systems studied included oil palm, teak plantation, uncleared forest, cassava land and sugarcane land. Soil samples were collected randomly at four locations in each sample plot at the depths of 0-15 cm, 15-30 cm and 30-75 cm and the soils thoroughly mixed to obtain a composite sample. Soil samples were analyzed for particle size, pH, organic matter (OM), total nitrogen (TN), Available phosphorus (Av. P), Available potassium (Av. K), Sodium (Na), Calcium (Ca), Magnesium (Mg), Cation exchange capacity (CEC) and Exchangeable acidity (Ex. A). ANOVA (analysis of variance) was used to test the significance of the changes. The results of the study indicated that, the pH of the land use areas ranges from 4.8 to 6.5 and the soil was sandy. Cassava and sugarcane land resulted in significant decreases in OM, TN, Av. P, Av. K, Ca, Mg, Na and CEC, while the exchangeable acid was high in cassava land, Whereas, the highest values of the same parameters were found under uncleared forest, oil palm and teak plantation land. The results of the study showed that forest clearing and subsequently cultivation and tillage Practices resulted in the decline of the soil quality in cassava and sugarcane land and these changes affect soil properties. Therefore, there should be integrated land management options for different land-use systems to sustain agricultural productivity.

Field experiment was conducted to study the effects of crop residues in combination with NPK fertilizer (NPKF) on soil chemical properties and growth performance of white seed melon at Ile-Oluji, Ondo State Nigeria. The experiment involved applications of cocoa bean husk (CBH), cocoa pod husk (CPH), cocoa pod waste (CPW), kola pod husk (KPH), Tithonia diversifolia (weed much (WM) in combination with NPK 15:15:15 Fertilizer to produce twelve treatments at 4 t ha-1 CBH + 200 kg ha-1 NPKF, 4 t ha-1 CBH + 100 kg ha-1 NPKF, 4 t ha-1 CPH + 200 kg ha-1 NPKF, 4 t ha-1 CPH + 100 kg ha-1 NPKF, 4 t ha-1 CPW + 200 kg ha-1 NPKF, 4 t ha-1 CPW + 100 kg ha-1 NPKF, 4 t ha-1 KPH + 200 kg ha-1 NPKF, 4 t ha-1 KPH + 100 kg ha-1 NPKF, 2 t ha-1 WM + 200 kg ha-1 NPKF, 2 t ha-1 WM + 100 kg ha-1 NPKF, 300 kg ha-1 NPKF and control, all the amendments tested significantly improved soil chemical properties and growth performance of white seed melon relative to control. Three cocoa plants residues in combination with NPKF at reduced rates 4 t ha CBH + 200 kg ha-1 NPKF, 4 t ha-1 CPW + 200 kg ha-1 NPKF and 4 t ha-1 CPH + 200 kg ha-1 NPKF respectively significantly (p < 0.05) improved soil pH, organic matter (OM), available P, exchangeable k, Ca and Mg, Na, Fe, Al and ECEC among the amendments tested. All treatments increased number of leaf, branches and vine length of white seed melon compared to control. 4 t ha-1 CBH + 200 kg ha-1 NPKF, 4 t ha-1 CPW + 200 kg ha-1 NPKF, 4 t ha-1 CPH + 200 kg ha-1 NPKF, had highest value of crop branches.