Spatial variability and classification of soils on a Legon hill catena in the Accra Plains, Ghana

Abstract

Properties of five soils developed on different positions of a Legon hill catena in the Accra Plains, Ghana, were studied. Nyigbenya, Toje, Adenta, Haatso and Alajo series were located on the higher upperslope, lower upperslope, middle slope, lower slope and bottom slope positions, respectively. All the soils had bulk density between 1.00 and 1.40 Mg m -3 and pH (KCl) > 5.1. Alajo series showed relatively higher pH (H 2 O) (6.6 to 7.6), than all the other soils. Clay fraction increased from 263 g kg -1 at the upper to 721 g kg -1 at the bottom slope. All the soils except Alajo series showed very low levels of exchangeable bases and cation exchange capacity (CEC). Alajo series contained close to 10-fold levels of exchangeable bases and CEC compared to those of the other soils. Phosphorus retention was low (< 35%) in all the soils except the last horizon of Alajo series which showed a very high amount (96.2%) and had stronger correlation with clay content of the upper 30 cm of the soils. Alajo series showed the highest levels of organic C (1.8 to 9.5 g kg -1). This study shows that: (1) The properties of Nyigbenya, Toje, Adenta and Haatso series suggest that they were formed from stratified parent materials; (2) The within and across pedon textural differences along the catena were caused by sedimentary differentiation, illuviation and pedogenic formation of clay in the subsoil; (3) The levels of phosphate retention, CEC and exchangeable bases in the soils could be attributed mainly to the type and amount of clay they contained. Nyigbenya and Toje series were classified as Rhodic Kandiustalf according to Soil Taxonomy. Adenta series was classified as Typic Kandiustalf and Haatso series as Kandic Haplustalf. Alajo series, on the other hand was classified as Typic Natraquert. According the WRB classification system, Nyigbenya and Toje series were Nitisols whereas Adenta and Haatso series were Lixisols. Alajo series was classified as Natric Vertisol.

Variations in Soil Chemical Properties, Bacteria and Fungi Populations Along Slope Positions and Profile Depths in Terraced and Non-terraced Lands of Rwanda highlands

“…Naturally, plant and animal residues are concentrated in surface layers of soil. A similar trend was reported by Eze (2015) and Lawal et al(2014).…”

“…These may vary due to higher contents of organic matter in top slopes and surface soils. A similar trend was reported by Eze (2015) and Lawal et al (2014).…”

Charge Properties and Fingerprints of Some Urban and Peri-Urban Garden Soils in Accra, Ghana

“…These are most preferred by farmers (Ericksen and Ardón 2003) and gardeners because they provide good soil tilth when the SOM content is substantial. Similar textural classes were encountered in the Accra plains (Eze 2015), and are essential for water relations as shown in the WHC (Table 1). For effective irrigation, the textures are suitable and could be improved under improved irrigation systems that account for evapotranspiration rates of the area and crop water requirements.…”

“…This is essential since "thermal and moisture regimes of soils" are factors that limit soil productivity in the tropics (Mueller et al 2010). Further, the bulk densities (Table 1), some of which were found by Eze (2015), were too high to be acceptable for a garden except that of the KB Ferric Acrisol, but were lower than those of Owoade et al (2021). Soil texture and SOM contents seemed to have in uenced the bulk density although no clear correlations were found.…”

Charge properties and fingerprints of some urban and peri-urban garden soils in Accra, Ghana

“…These are the reasons for which a bulk density of 1.2 Mg/m 3 is assigned a soil quality indicator rating of 80% whereas a bulk density of 1.4 Mg/m 3 has almost a rating of 40%(Weil and Brady 2017).The pH water > 5.5 of the soils suggests less risks of phosphate retention as well as Al and micronutrients toxicities since exchangeable Al is precipitated at pH < 5.2(Pansu and Gautheyrou 2007). The pH values corroborates those ofEze(2015) for the same soil types located in other parts of the Accra plains, but were below those found in Ferric Acrisols of the CS zone(Owoade et al 2021). Such pH values are rated high in during soil quality assessment…”