Nutrient release dynamics of an accelerated compost: A case study in an Alfisol and Ultisol

Abstract

Acceleration of composting process could influence fertilizer-efficiency of the accelerated composts. This study therefore evaluated the nutrient release dynamics of different rates of a commercial accelerated compost ( OBD-plus ) in two soils described as Alfisol and Ultisol, under laboratory incubation study, in order to generate information for simulation under field conditions. Accelerated compost (AC) at the rates of 30, 60, 90, 120, 150 kg N ha -1 , mineral fertilizer (NPK 15-15-15) and conventional compost (CC) at 60 kg N ha -1 , were each mixed with 2 mm sieved soil (Alfisol and Ultisol) in cups, and arranged in a completely randomised design with three replications. Soils without amendment served as control. The treated soils were retrieved at 2, 4, 6, 8, 10 and 12 weeks of incubation (WOI), air dried and analysed for pH, organic C, N, P and K, and data analysed using regression test. The results revealed that the 60 kg N ha -1 AC improved the pH, OC, N. P, K by -2%, 11%, 3%, 141% and 4% respectively, across the WOI, on the average of performance in the two soils, comparable with mineral fertilizer (-5%, 8%, -1%, 76%, 4% respectively) and CC (11%, 40%, 3%, 773%, 10% respectively). The 60 kg N ha -1 AC significantly correlated (p<0.05) with time of incubation only with respect to P (0.934) and gave a similar nutrient release pattern compared with mineral fertilizer and CC, in terms of C, N, P and K in both soils. It therefore showed that the accelerated compost evaluated could mineralize in a way similar to conventional compost and mineral fertilizers, despite its shorter composting duration to maturity.