PREDICTING THE DECOMPOSITION RATE, MASS LOSS, AND NUTRIENT RELEASE OF SINGLE AND MIXED LEAF LITTER TYPES USING DECOMPOSITION MODELS IN THE NORTHERN GUINEA SAVANNAH OF NIGERIA

Background: This study presented a non-linear model to biologically describe the decomposition pattern, mass loss and nutrient release of four leaf litter species: Khaya senegalensis (African mahogany), Mangifera indica (Mango), Gmelina arborea (Beechwood), Eucalyptus camaldulensis (River red gum) and a mixture of the leaf litters using the standard litter bag technique. Objective: To explore different mathematical decomposition decay models in evaluating the decomposition rate and the relationship between mass loss and chemical parameters of some selected trees in Nigeria's northern Guinea savannah.  Methodology: The experiment was a Completely Randomized Design with three replications. Fifteen litter bags were randomly placed in the field and retrieved at intervals of 0, 14, 28, 42, 56, 84, and 112 days (16 weeks).  Three non-linear models were used to estimate the decomposition rate of the litter. Pearson correlation analysis was used to determine the relationship between mass loss and chemical composition. Results: Decomposition pattern gradually increased from 7 % up to 78.5 % by week 0 to 16 weeks. The leaf litter of Mangifera indica had the highest mass loss (62.9 %), followed by the litter mixture (44.0 %), Eucalyptus camaldulensis (43.6 %), Gmelina arborea (40.5 %) and Khaya senegalensis (39.3 %). Single exponential model (Adj R2=93.25-98.59%), double exponential model (Adj R2=87.93-98.98%), and three parameters asymptotic negative exponential model (Adj R2=93.82-98.84%), described the decomposition process efficiently. Correlation analysis of mass loss and chemical composition was highly significant (p ≤ 0.05), among all the leaf litter chemical properties, organic carbon, phosphorus, and nitrogen were the restraining factors. Implication: The mass loss was closely linked to the chemical properties of all the litter types. Among these properties, organic carbon and phosphorus were the limiting factors. Conclusion: We conclude that the single-leaf litter of Mangifera indica and Khaya senegalensis were superior in chemical composition, and decomposition than the mixed-leaf litter therefore they have the potential to enhancing soil fertility in the study area.