Litter Decomposition, Carbon and Nitrogen cycling under different Land Use systems

Abstract

Changes of forests to agricultural lands are one of the most concerns in environmental degradation and world climate change. Transformation of one land use system into another and different management practices can affect soil structure, soil organic carbon and nitrogen. The study aims to elucidate on the effects of litter decomposition and land use at five depths in Alfisol of Southwest Nigeria. Investigations were carried out on soil physicochemical, biochemical and microbial properties. The experiment was conducted using 5 x 5 factorial with five land use (secondary forest (SSF), Tectona grandis (SST), Elaeis guineensis (SSA), cultivated land (SSC) and grassland (SSG)) and five depths (0-5, 5-15, 15-30, 30-60 and 60-100 cm). The experimental design was randomized complete block design (RCBD) with three replicates, making seventy five (75) treatments combinations. The land use systems generally influenced bulk density (1.31 g/cm3), moisture content (3.31 %), and total porosity (54.58 %) with the highest values recorded in SSA, SSF and SST respectively. Likewise, highest values for pH (6.87), organic carbon (0.51 %), cation exchange capacity (28.15 cmolc/kg) were recorded at SSC but carbon forms differ significantly while nitrogen forms were not significant across land use. Enzymatic activities recorded highest at the surface layer of the land use systems. Microbial population for fungi (6.03 sfu/g x 104), actinomycetes (6.03 cfu/g x 104) and nematode (11.48/100 g soil) recorded highest value at SSA while bacteria (6.31 cfu/g x 104) was at SSF. β-glucosidase correlates significantly with other biochemical properties while pH shows no significant correlation at P>0.05. The study was able to identify that secondary forest holds more carbon content and promote activities of microbes better than other land use system. Also, fungi were found to be the most active in the decomposition of litter in oil palm plantation. This reveals the influence of litter decomposition as a resource pool within the soil ecosystem and its importance in maintaining soil functions