Release of nutrients and biomass loss due to leaching from the leaves of Parkia biglobosa and Gliricidia sepium trees in the transition zone of the Nigerian rainforest ecosystem

Abstract This study evaluated the release of nutrients and biomass loss due to leaching from the leaves of Parkia biglobosa (Parkia) and Gliricidia sepium (Gliricidia) trees in the transition zone of the Nigerian rainforest ecosystem. 50 g of fresh green biomass was pruned from the Forest Nursery, Federal University of Agriculture, Abeokuta, Nigeria. The pruned samples were weighed into a 500 mL beaker and soaked in 250 mL water for different durations: 24, 48, 72, 96, 120, 144, and 168 h (h) and repeated six times. Data were analyzed using One Way Analysis of Variance. Nitrogen (N) and organic carbon (OC), and lignin (L), lignin to nitrogen ratio (L: N), lignin plus polyphenol (PP) to nitrogen ratio (L + PP): N, acid detergent fiber and cellulose had significantly ( p ≤ 0.05) higher and lower values (g/kg) (27.70 and 9.68, 138.34, 2.04, 1.56, 201.23 and 187.84) respectively in Gliricidia; and this cheered its decomposition and nutrients release. N, phosphorus, and potassium had higher values (21.50 g/kg, 88.28 mg/kg, and 10.32 mg/kg) at 24 h in Gliricidia. 56% mass was lost through leaching in Parkia at 144 h, while 28% was lost in Gliricidia at 72 h, 96 h, and 168 h. Gliricidia had higher values (8.04, 3754 μS/cm, 8840 mg/L, 1969 mg/L, and 380 mg/L) in pH, electrical conductivity, volatile solids, total dissolved solids, and total suspended solids at 168 h, 168 h, 144 h, 168 h, and 24 h, respectively. In conclusion, the leaves of Gliricidia and Parkia tend to release nutrients when decomposed; however, the leaching of nutrients must be minimal for effective plant use. Also, the leaves of these tree species can be used as alternate remedy to improve soil fertility for tree and crop production. It is therefore recommended that Parkia green leaves are less prone to leaching than Gliricidia and thereby preserve their nutrient potential.