Chapter 1. Introduction

Ghana is located on the southern coast of West Africa, between latitudes 4° 44’ N and 11° 11’N and longitudes 3° 11’ W and 1° 11’ E.

The country is divided into ten administrative regions. These regions are shown in Table 1.

According to the World Bank, in 2003 the country had a population of 20.4 million people with a population growth rate of 1.7 percent per annum. Agriculture accounted for 35 percent of the GDP.

The total and rural populations of the different regions in 1999 are given in Table 2.

TABLE 1
The regions of Ghana and their capitals

TABLE 2
Population

TABLE 3
Land use

* Others: Forest reserves and savanna woodlands.
Source: MOFA, 2003.

Land use

The land areas according to their utilization are given in Table 3 and Figure 1.

Agro-ecological zones

The country is divided into six agro-ecological zones on the basis of their climate. The natural vegetation is determined by the different climatic conditions and influenced by different soil types. These agro-ecological zones from north to south are: Sudan Savannah Zone, Guinea Savannah Zone, Transition Zone, Semi-deciduous Forest zone, Rain Forest Zone and the Coastal Savannah Zone (Figure 2).

Climate

The climatic conditions of the different agro-ecological zones are shown in Table 4. The wet and dry seasons are determined by rainfall and temperature. The Tropical Eastern Coastal Belt is warm and comparatively dry, the southwest is hot and humid and the north is relatively hot and dry, compared with the other parts of the country. The mean annual rainfall ranges from 800 mm in the Coastal Savannah to 2 200 mm in the Rain Forest. The rainfall pattern is uni-modal in the Sudan and Guinea Savannah Zones and bi-modal in all the other zones (Table 4).

Soils

The soils of Ghana are highly weathered with predominantly light textured surface horizons in which sandy loams and loams are the common textural classes. The lower soil horizons have relatively heavier textures varying from coarse sandy clay loams/sandy loams to clays. Heavier textured soils are normally abundant in the valley bottoms, which are ideal for rice cultivation. The B-horizons - subsurface horizons showing features of accumulation or significant alterations - may contain abundant coarse material either as gravel or stone/concretionary materials. The coarse nature of the soils has an adverse impact on their physical properties, particularly their water holding capacity. Thus crop water stress is not uncommon during the growing season. The soil map of Ghana based on the FAO Legend is given in Figure 3.

TABLE 4
Climates of the agro-ecological zones

Source: Adapted from data from the Meteorological Department, Legon, Accra, Ghana.

The average fertility status of soils of the different regions is presented in Table 5. The levels of organic carbon, nitrogen and available phosphorus are generally very low. Figures are not given for potassium since it is mostly abundant in the soils of Ghana.

TABLE 5
Average soil fertility status of some regions

Source: Soil Research Institute (SRI) CSIR - Kumasi.