Abstract:
Food insecurity and declining soil fertility across much of sub-Saharan Africa in recent decades have led to pursuit of alternative nutrient management strategies for both improving crop yields and the restoration of degraded soils. In this respect, a 3-year field based studies involving two sites (Ayuom and Kwadaso) of contrasting soils (Suko and Nzima series) in the semi-deciduous forest zone of Ghana was initiated in year 2003. The treatments involved 5 organic resources of different qualities (in terms of N, lignin and polyphenol) with and without inorganic N application. The organic resources were applied at two application rates; 1.2 t C ha−l year.−l and 4 t C ha−l year.−l in the major season and the residual effect evaluated in the ensuing minor season. Cumulative maize grain yield (3 years) at Ayuom on the Suko series for the major season showed that 1.2 t C ha−lL. leucocephala+120 kg N ha−l proved to be the most effective treatment with yield of almost 18,000 kg ha−l. At Kwadaso on the Nzima series however, 4 t C ha−l Cattle manure+120 kg N ha−l for the minor season was the most effective. At both sites, major season grain yields were generally higher than minor season. Furthermore, between cropping seasons, maize yields were superior on the Suko series than the Nzima series. To improve food security in the semi-deciduous forest zone of Ghana, soil nutrient management to restore soil fertility should take into consideration: soil type, cropping season, organic resource quality and quantity as well as their interaction with inorganic N.