Fertility Capability Classification of Some Soils with Aquic Moisture Regime in Delta State, Nigeria

Abstract

Fertility Capability Classification (FCC) of some soils with aquic moisture regime in Delta State, Nigeria was investigated. Three mapping units namely: Mangrove swamps, river flood plain, and inland valley located at Burutu, Ossissa and Okwagbe were used for the study. Soil samples were collected from 0--25 and 25—60 cm depth from each of the mapping units and analyzed for some of their physico - chemical properties. The fertility capability classification system in which Types, Substrate Types and Modifers were used in classifying the soils based on the results of the physico- chemical properties evaluated. The results of the study showed that the texture of the soils ranged from clayey in the mangrove swamps to loamy and sandy loam in the river flood plain and inland valleys soils respectively. The soils were strongly to slightly acidic (4.6 – 6.3) in water and KCL solution. The values of organic carbon ranged from 5.58 – 7.65 gkg^-1 in the mangrove swamp soils and 2.20 – 3.18 gkg^-1 in the river flood plain and inland valley soils. Available phosphorus were low (3.20 – 7.50 mgkg^-1). The values of total nitrogen were low (0.95 – 2.24 gkg^-1). The exchangeable bases particularly sodium ion was high in the mangrove swamp soils 5.01 – 5.65 Cmolkg-1 but low in the river flood plain and inland valley soils (0.17 – 0.18 Cmolkg^-1). The percent Base saturation were moderate to high in the river flood plain and mangrove swamp soils (17.3 – 58.8%) and low in inland valley (12.9 – 14.0%). In the application of the FCC system, the soils are characterized by the following fertility indicators: C,O,X,h, g,w, s and for mangrove swamp, soils and L, h, e, k and i for the river flood plain and inland valley soils respectively. The common limiting factors include excessive wetness (w), high acidity (h), low P. content (i), salinity (s) especially with mangrove swamps, and low potassium reserves (k).

Keywords: Fertility capability classification, and aquic moisture regime