Effect of mulch types on nutrient composition, maize (Zea mays L.) yield and soil properties of a tropical Alfisol in Southwestern Nigeria

Field investigations were carried out to evaluate the influence of shrub and herbaceous mulch types on soil properties and nutrient composition of maize (Zea mays L.) at the Teaching and Research Farm of the Federal University of Technology, Akure in the rainforest zone of southwestern Nigeria in 2013 and 2014 respectively. The shrub mulch; Gliricidia sepium and Tithonia diversifolia, herbaceous mulch; Calopogonium mucunoides and Moringa oleifera were applied at the rate of 5 t ha-1. Application of NPK (20:10:10) fertilizer at the rate of 200 kg ha-1 was included as the standard treatment for the experiments. The treatments were laid out in randomized complete block design (RCBD) with three replication. The growth, agronomic parameters and nutritional quality of maize (Zea mays L.) were monitored and determined in both experiments. Results indicated that herbaceous mulch types and NPK fertilizer significantly (P<0.05) increased the number of leaves, plant height and leaf area when compared with the control in both years. Significant increases in yield parameters over the control were obtained for the NPK fertilizer treatment. In 2013 and 2014 cropping season NPK 20-10-10 treatment significantly produced the highest cob yield but was not significantly higher than the yield from Gliricidia sepium treatment in 2014. Soil organic carbon, total nitrogen (N), potassium (K), and exchangeable cations were positively stimulated by herbaceous mulches while residual phosphorus (P) was increased by NPK fertilizer treatment. Mulched treatments significantly increased crude protein, carbohydrate, nitrogen, phosphorus and ash content of maize grain in both years of cropping season thereby improving nutritional content of maize grain. Therefore, shrub and herbaceous mulch treatments applied at 5t/ha-1 could be applied alternatively in lieu of scarce and expensive inorganic fertilizer for improved maize yield, soil properties and nutrient composition.