Organic amendment of an ultisol: effects on soil properties, growth, and yield of maize in Southern Guinea savanna zone of Nigeria
Background:The Southern Guinea savanna zone of Nigeria is characterized by inherently low soil fertility status and rapid nutrient depletion especially soil organic matter. However, this zone is characterized by abundant agricultural land and is a potential for crop production. Field experiments were conducted in order to evaluate the effects of integrated use of agricultural waste materials and compound mineral fertilizer on soil and plant nutrient status, growth, and yield of maize in ultisol in the Southern Guinea savanna zone of Nigeria. Results:Application of organic waste alone and in combination with mineral fertilizer enhanced root and shoot biomass, leaf area development, and yield and components of maize. Treatment effects were significant on growth characteristics of maize (stem girth, leaf area, plant height and days to 50% tasselling, root and shoot biomass). Sole application of NPK fertilizer (400 kg/ha) was not significant over the combined use of poultry manure and NPK on girth, leaf area, and plant height. Mean values of stem girth, leaf area, and plant height ranged between 2.05 and 3.8 cm, 0.26 and 0.54 m2, and 84.7 and 209.4 cm, respectively. Root and shoot dry weights were highest under sole NPK application compared with plots where either sole wastes or wastes in combination with reduced NPK were application of NPK fertilizer (400 kg/ha) was not significant over combined use of poultry manure and NPK on stem applied. Integrated use of agricultural wastes and NPK also enhanced root and shoot dry weights compared with sole application of wastes as well as seed weight per plant, 100-seed weight, and number of seeds per cob and grain yield. Among the agricultural wastes applied, poultry manure enhanced the growth and seed yield characteristics of maize. This treatment increased the seed weight per plant, number of seeds per cob, 100-seed weight and seed yield by 55.6%, 66.5%, and 55.4%, respectively over Chromolaena and neem seed cake. Chromolaena and neem seed cake produced similar grain weight per plant, 100-seed weight, number of seed per cob, and seed yield. Poultry manure significantly enhanced the growth and seed yield characteristics of maize over Chromolaena and neem seed cake.Conclusions:Integrated use of organic wastes and mineral NPK fertilizer showed promising potential for improving soil fertility, growth, and yield of maize in the Southern Guinea savanna agroecological zone of Nigeria. It is recommended that poultry manure at 7 t/ha plus NPK fertilizer at 200 kg/ha be adopted for maize cultivation in the study area.