Abstract

Impacts of landuses [old home garden (HG), oilpalm plantation (OP), fallow arable field (FA), grass lawn (GL)] on physico-chemical properties of an ultisol on a flat in the Coastal plains sand of Imo State, Nigeria were evaluated. Landuse significantly (at 5%) influenced the properties sand, organic matter (OM) content, soil reaction (pH), exchangeable cations Ca, Mg, K, exchangeable acidity (Al+H), effective cation exchange capacity (ECEC), base saturation (BS); while available phosphorous (av.P), Ca, Mg, K, Al+H, varied most within and among the management units. Properties varied least in HG, but most in FA and GL. Strong soil acidity and associated problems of nutrient (e.g. Ca, Mg, K) deficiencies, nutrient imbalance, low ECEC were the main limiting factors. The ratio Ca+Mg/Al+H, among other indices OM, Ca+Mg, Al+H, ESP, captured the soils’ degradation best. On its basis, the soils’ qualities were in the order, HG > OP > FA > GL. Management should aim at meeting the conditions of HG and that should include liming to correct nutrient imbalance as it had not been mitigated by long fallow. Indices identified should be considered in developing quantitative models for estimating soil quality in the location of study. Soil property variability as influenced by land fragmentation in the area needs further investigation using geostatistical technique.

Key words: Management, Coastal plains sand, indices of soil quality, soil degradation, soil productivity.