Decomposition Rates of Plant Residues and Nutrient Dynamics under Field Conditions in a Humid Tropical Environment

Abstract

In a field incubation experiment to determine the rate of plant residues and nutrient dynamics in a humid tropical environment using litterbags, the decomposition of and nutrient release from Dovewood, Elephant grass, Velvet bean, Guinea grass, Water hyacinth  and wood shavings were monitored for 56 days. Litterbags were buried 10 cm in soil and were retrieved every 14 days and oven-dried at 60°C for 48 h for dry and organic matter determinations. Thereafter, litterbag contents were prepared and stored for the determination of nitrogen (N) and phosphorus (P) contents. Decomposition was highest in bags of water hyacinth (k = 0.4464) and lowest in wood shavings (k = 0.0668). The percentage of soil amendments remaining after 56 days of decomposition were 48% for Dovewood, 38% for Elephant grass, 34% for Velvet bean, 29% for Guinea grass, 0% for water hycinth and 85% in Wood shavings. Decomposition rate did not affects N and P release patterns, however nitrogen release from Dovewood was Highest (k = 0.2570) and wood shavings had the Lowest (k = 0.1170). Guinea grass had the highest P release (K = 0.3751) whereas wood shavings and Velvet grass had the lowest P release (k = 0.1630).The chemical composition of plant residues was responsible for the differences in decomposition rates and nutrient release. The use of Dovewood and Guinea grass therefore were recommended as nitrogen and phosphorus sources respectively.