Variation in Soil Chemical and Microbiological Properties as a Result of Yearly Amendment with Organic Fertilizer

Millions of organic fertilizers are produced annually all over the world. Substantial quantities of these were crop residues and the remaining being animal waste based. Meanwhile maintaining and improving soil fertility in the tropic is essential for increasing food production for rapidly expanding the population. This project work, therefore, investigated the variation in soil chemical and microbiological properties as a result of yearly amendment with compost. The experimental site was the Organic Agricultural Farm located within the Federal University of Agriculture, Abeokuta. Soil samples were collected between 0 – 15 cm depth using soil auger and the samples were analyzed for the following soil parameters; total viable counts, total fungal counts, microbial biomass carbon, microbial biomass nitrogen, percentage organic carbon, microarthropod counts and earthworm counts. The experiment was a split-plot design using 2 varieties of tomato x 3 levels of compost and two durations of application. The variations include one improved variety (UCB 8) and a local variety (Beske), rate of compost – (0, 10, and 20) kg/ha and years of application (one and two years). Results generally showed that: duration has a significant effect on viable counts, microarthropod counts, microbial biomass P, microbial biomass C and percentage organic carbon but has no significant effect on fungal counts, microbial biomass nitrogen, and earthworm counts. The results indicate that application of compost manure is the preferred option to enhance SOM accumulation, improve soil fertility and quality, and increase tomato yield.