ABSTRACT

A detailed soil survey of 1.8ha forest pedosite at Michael Okpara University of Agriculture, Umudike (MOUAU), Umuahia, Abia State, Nigeria, was conducted to evaluate land capability, degradation status and pedodiversity of the site. Rigid grid method of soil survey was adopted at a scale of 1: 10 000. Datas obtained were analyzed using descriptive statistics. The soil samples were carried to the laboratory to analysis its physical and chemical properties. Three profile pits were dug measuring 1m x 2m, its depth ranged 0.40 -1.50 m Results showed that two soil mapping units FPMOUAUI and FPMOUAU II were identified. Mapping unit FPMOUAU I (0.25ha) is well drained, shallow (≤ 50 cm deep), gravelly and is located on an elevation ranging from 103 – 108 m above sea level. Mapping unit FPMOUAU II (1.55ha)is deep (> 100 cm deep), imperfectly drained, and found on a lower landscape (≤ 103 m above sea level) to mapping unit FPMOUAU I. Using silt-clay ratio as an index of degradation, the soils are degraded ranging from 0.17 – 0 5 and 0.12 – 1 8 for mapping units FPMOUAU I and FPMOUAU II, respectively. At the epipedon, the soils are strongly to moderately acid (pH{H₂0}4.9 – 5.8), medium to high in organic matter (2.27 – 5.8 %), low to high in total N (0.07 – 0.34 %), low to high in available P (14 – 29 mg/kg) and medium in exchangeable K (0.24 – 0.33 cmol/ kg). The soils are classified as Lithic Udorthents (USDA); Eutric Loamic Regosols (WRB) for mapping unit FPMOUAU I and Typic Paleudalfs (USDA); Stagnic Loamic Luvisols (WRB) for mapping unit FPMOUAU II. The pedosite is arable land belongs to Land Capability Class II. However, land capability unit for mapping unit FPMOUAU I is Class IIs based on shallowness of the soils and Class IIw for mapping unit FPMOUAU II due to imperfect drainage. The Shannon entropy was 0.65 and evenness was 0.69, while the Simpson’s dominance index was 0.05 indicating that the soils are not homogeneous. I recommend that the need to apply soil conservation measures such as construction of an embankment at the upper part of the forest pedosite to reduce run off into the pedosite causing its degradation beyond expectation. The land capability classification has generated data to assist in the choice of appropriate trees (shallow – rooted and deep - rooted) for afforestation programme. The heterogeneity of the site as further revealed by the pedodiversity is a vital soil information to aid in the management of the forests