INFLUENCE OF ORGANIC AMENDMENT AND MYCORRHIZA ASSOCIATION ON COWPEA

Abstract

Organic amendment has a great potential to increasingly replace the use of mineral fertilizer and pesticide for sustainable crop production. A screen house experiment was conducted to evaluate the effects of organic amendments on the growth of two cowpea varieties with and without mycorrhiza inoculation. The experiment was a completely randomized design and a factorial combination of two cowpea varieties (IT99K573-1-1 and Oloyin), two levels of inoculation with mycorrhiza (with and without) and five levels of organic amendments (formulated from palm kernel cake, oil palm empty fruit bunch ash, plantain peels and Tithonia). Each treatment combination had six replicates. Organic amendments were incorporated two weeks before planting of cowpea seeds and inoculation of mycorrhiza to the soil. Data were collected on cowpea growth attributes such as the number of leaves, number of branches, plant height, stem girth and leaf area. Data were subjected to analysis of variance using the GenStat Discovery Edition 4 and treatment means were separated using the Duncan’s Multiple Range Test at α0.05. Organic amendment 5 (control) was best in terms of mean values for number of leaves, number of branches and plant height. Cowpea plants inoculated with mycorrhiza were best for all growth attributes. In the residual experiment, Oloyin variety with organic amendment 3, previously inoculated with mycorrhiza and had the highest mean number of leaves and oloyin variety with organic amendment 4 not previously inoculated with mycorrhiza and had the highest mean plant height. Therefore, we need to transform and use some of the agricultural waste that are rich in nutrient particularly in phosphorus as a source of organic fertilizer for cowpea cultivation.