Leaf Litter Decomposition and Nutrient Release in a Rubber Plantation in Southwest Nigeria
Adedeji, Oludare H.
Department of Geography and Regional Planning, Olabisi Onabanjo University, PMB 2002, Ago Iwoye, Nigeria.
Email: hakeemdare1222@yahoo.co.uk
Accepted on May 02, 2008.
Abstract
Decomposition and nutrient release pattern of tropical agroecosystems such as those of rubber (Hevea brasiliensis) are rarely studied compared to those of the temperate regions. This study describes the weight loss and nutrient release pattern from decomposing litter of a rubber plantation of different age stands (40-, 15-, and 5-year-old). Decomposition rates of 15-year-old leaf litter were fastest followed closely by the 40-yearold. In the 15-year-old plot, a significant reduction in mass (c. 70%) was observed within the first six months (p<0.05). Weight loss (95%) was completed by the by the 9th month in the 15-year-old stand while it was 10th and 11th month respectively in the 40-year-old and 5-year-old plots respectively. The pattern of weight loss exhibited an initial rapid decay phase (especially in the rainy season) followed by slow decay rate. Pattern of change in the concentration of N, P, and K was approximately linear to mass loss. The largest decay coefficients were observed in the 15-year-old rubber plot (0.338). The mineralization of P was similar for the three stands, but 15-year-old litter released large amounts of K. Levels of exchangeable K were significantly increased in 15-year-old litter. It can be concluded that 15-year-old litter is easily decomposable. There is therefore the need to be felled and replant old rubber plots and supplement nutrient in the 5-year-old plot with external inputs in order to improve nutrient cycling and promote sustainable production