The study was conducted to investigate fertility status under four different land use types (oil palm plantation, pineapple orchard, cassava cultivated land and fallow land use system) in Umuekem, Ohaji/Egbema of Imo State, Nigeria. Composite samples were collected from various depths (10-15cm, 15-30cm, 30-45cm) across these land use patterns and analyzed in the laboratory using the standard procedure. Data generated were subjected to statistical analysis. Results obtained showed significant differences (p ≥ 0.05) in silt-clay ratio, bulk density, total porosity, water holding capacity, soil pH, organic carbon, available phosphorus, TN and ECEC across the four land use types studied. The soils were predominantly loamy sand surface and sandy clay loam in the subsoil exception of pineapple orchard with sandy loam topsoil over sandy clay loam subsoil. The silt clay ratio (SCR) showed ranges of 0.10-0.30, 0.10-0.36, 0.07 – 0.30, and 0.06- 0.20 in land use types of oil palm plantation, pineapple orchard, cassava cultivated land and fallow land respectively. The bulk density ranged of (1.61 – 1.77 g/cm3) for oil palm, (1.34 – 1.58 g/cm3) for pineapple (1.42 – 1.49 g/cm3) cassava and (1.45 – 1.48 g/cm3) in forest land use system. The soils of the four land use types were generally acidic. The mean values of soil pH (H20) were oil palm plantation (5.11), pineapple orchard (5.03), cassava cultivated land (5.35) and fallow land (5.40). The soil pH recorded low variation in all the land use types. The organic carbon and total nitrogen recorded high variation (>52.57% < 85.67%, >79.19 < 95.77) in all the different land use types. Calcium-magnesium ratio (Ca: Mg) recorded high variation (37.36%) in forest land use system, low variation (18.77%) in pineapple orchard and moderate in cassava (27.51%) and oil palm plantation (28.23). The low Ca: Mg ratio inhibits uptake and causes Ca deficiency thereby resulting in low fertility status of the soil. C: P recorded high variation (≥ 53.77% ≤ 77.73%) in all the studied land use types. O.C correlated positively and highly significant with available phosphorus, ECEC and T.N. The findings also indicated that bulk density correlated positively with ECEC and percentage base saturation. It is recommended that land use approach should be adopted for effective and sustainable management of the soil fertility.
Keywords: Fertility status, Soils, Land use types
REGULATORY SUPPORT FOR ENVIRONMENTAL MONITORING IN THE LAND USE SYSTEM