UNVEILING THE NATURE OF CARBON DECOMPOSITION ON DIFFERENT ORGANIC MANURE SOURCES: THE IMPACT OF TEMPERATURE REGIMES IN A SUBTROPICAL CLIMATE

Abstract

Organic sources are vital for crop nutrient management, but nutrient release from organic manure depends on temperature and other factors. We conducted a laboratory incubation study to investigate how temperature (15, 25, 35°C) affects the decomposition of common organic manure, which has not yet been explored in Bangladesh. The organic manures used in this study are poultry manure (PM), vermicompost (VC), bio-slurry (BS), cow dung (CD), water hyacinth compost (WHC) and rice straw compost (RSC), which were compared with a control treatment (only soil). Carbon mineralisation and CO2 emission from microbial respiration varied among organic manures and temperature regimes. The RSC- and WHC-treated soils had a higher C mineralisation than the other manures at 35°C. The mineralisation of C among the organic manures followed the order: RSC > WHC > CD > VC > BS > PM > control. Among the temperature regimes, C mineralisation followed the order 35°C > 25°C > 15°C. Manure mineralisation was associated with mineralisable C pools (carbon availability factor, Caf), and 16.4–36.5% organic C was released. Irrespective of temperature regimes, the highest easily mineralisable Caf was recorded in PM-amended soil, followed by VC-amended soil. RSC had the lowest Caf under all temperature regimes. The Caf values of all incubated manures were higher under a 35°C temperature regime. Compost preparation from organic manure and its utilisation as an integrated nutrient management component can play essential roles in mitigating climate change, reducing environmental degradation, and building more sustainable and resilient agrifood systems.