Abstract

Low soil fertility is one of the major factors responsible for low crop yields on small-scale farms in Africa. The use of Chromolaena odorata, Crotalaria junceaand Panicum maximum and their combination with NPK for improving soil fertility and maize yield was investigated in the semi-deciduous forest zone of Ghana. Each plant material was applied at two application rates, 1 and 3 t ha^-1. The field design was a randomized complete block with three replications. The plant materials caused an initial immobilization of nutrients which negatively affected maize grain yield in the major season. The plant materials plus N₄₅P₃₀K₆₀however, was able to provide nutrients that were sufficient to increase maize yields by over 85% relative to the control for the two consecutive seasons. N₉₀P₆₀K₆₀ application alone produced the highest grain yield of 4.65 t ha^-1 in the major season but less so in the minor season. Maize grain yield was not influenced by the quantity of plant materials application but was higher during the minor season than in the major season. The results of the study provide soil fertility management options for sustainable food production in the semi-deciduous forest zone of Ghana.

Key words: Fertilizer, maize, organic residues, soil fertility.