The population of Ghana is increasing at a rate of 1.7 percent per annum with almost two-thirds living in rural areas. Agriculture accounts for about a third of the gross domestic product (GDP), although this proportion is tending to decline. Ghana has extensive areas of land suitable for agriculture but the soils are infertile and only productive with proper management. The coarse nature of the soils has an impact on their physical properties and water stress is common during the growing season. Traditional, soil mining cultivation practices are still used extensively.
Cocoa is the main export crop but its production has been irregular. The crop has received little fertilizer. However, production increased in 2002/03 and, with improved practices including fertilization, there are good prospects for improving crop production. The production and exports of higher value crops, fruit and vegetables, are tending to increase. All fertilizers used in Ghana are imported. The most important group of fertilizers is that of compound fertilizers. The consumption of fertilizers fell substantially between the early 1980s and 2000 mostly because of adverse economic conditions but in 2002 it recovered to the former level. Maize accounts for about 40 percent of fertilizer use on food crops. The retail price of fertilizers increased several-fold between the 1980s and the 2000s largely owing to the depreciation of the Cedi. Subsidies on fertilizers were removed progressively from 1987 onwards. The correct use of fertilizers is particularly profitable on flooded rice and cassava but was profitable on most crops under 2002 economic conditions. Several crops respond positively to organic manures. Maize, for example, responds well to applications of NPK, to a lesser extent to application of manure, but in on-farm trials manure plus NPK gave a seven-fold increase over plots with no treatment. A special grade of fertilizer has been developed for use on cocoa. In on-farm trials, compared with unfertilized plots, a yield increase of 62 percent was obtained in the first year rising to 107 percent in the fourth year of application.
Among the important constraints to increased fertilizer use are inadequate and expensive credit, unsatisfactory marketing arrangements for the produce, the relatively small area under irrigation, insufficient funding of agricultural projects and inefficient use of fertilizers by farmers. Only 0.2 percent of the cultivated land is irrigated whereas several large irrigation schemes are underutilized.