GROWTH AND YIELD OF MAIZE IN RESPONSE TO GLIRICIDIA SEPIUM AND ACACIA AURICULIFORMIS MULCH OF VARYING QUALITY IN AKURE

Abstract

This study was undertaken to investigate growth and yield of maize in response to Gliricidia sepium (Jacq.) Kunth ex Walp. and Acacia auriculiformis A.Cunn. ex Benth. mulch of varying quality in a cut and carry agroforestry system so as to optimize the N-use efficiency of high and low quality litters. The experiment was laid out in Completely Randomized Design (CRD) with six treatments, each with three replicates. The treatments consisted of leaf mulches of 100g Gliricidia; 50g Gliricidia + 50g Acacia; 100g Acacia; 60g Gliricidia + 40g Acacia, 40g Gliricidia+ 60g Acacia and control. Oba Super 2 maize seeds (two seeds per hole) which is of ninety days maturity were sown on eighteen plots of 3m x 4.5m each with a buffer of 1m x 0.5 m between plots at a spacing of 30cm x 90cm (within and between rows) during the raining season. One week after sowing, the seedlings were thinned to one per stand and the treatment mulch was applied two weeks after sowing. Measurement of treatment effects on growth of maize commenced two weeks after mulch application and was repeated at 4, 6 and 8 weeks. At two and eight weeks after mulch application, surface soils at 1 - 10cm depth were collected around the maize stands for microbial population and diversity assessment. The maize cobs were harvested when they were dried on the field and the grain yield was evaluated. Significantly higher grain yield was observed between control plot and plots with applied mulches, though there was no significant difference when yield from the varied quality mulched plots were compared. At 8WAS and 10WAS, plots treated with 40g Gliricidia + 60g Acacia, 100g Acacia, 60g Gliricidia + 40g Acacia, 50g Gliricidia + 50g Acacia, 100g Gliricidia and control were significantly (P≤0.05) different in height. Also, maize plants mulched with 40g Gliricidia + 60g Acacia, control and 100g Acacia had significantly (P≤0.05) bigger stem diameters while others were not significant at 6WAS. The trend of growth in plant height and stem diameter showed that 40g Gliricidia + 60g Acacia had significantly best effects in terms of height and stem diameter. Plant physiological parameters as influenced in this study shows that 40g Gliricidia + 60g mulch produced higher number of leaves and below ground biomass. The effect of varying quality of mulches on soil temperature in this study shows that the temperature was lower when mulch was applied especially for 40g Gliricidia and 60g Acacia, 50g Gliricidia and 50g Acacia mulches. It was also found in this study that the population of microorganisms was higher at 4WAA than 8WAA. 13 forms of bacteria and 11 forms of fungi were isolated at 4WAA; 3 forms of bacteria and 7 fungi isolated at 8WAA. 3 bacterial and 7 fungi taxonomic groups were identical at 4 WAA and 8 WAA. However, 10 bacteria were exclusively found at 4 WAA and 6 fungi at 8 WAA.