Effects of vermicompost preparation and application on waste recycling, NH3, and N2O emissions: A systematic review on vermicomposting
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Abstract
Improper waste management and increasing environmental pollution from contaminated water and gaseous emissions are important challenges associated with rapid industrialization and the growing population. These issues pose threats to climatic change, agricultural ecosystems, human health, and the environment. Vermicomposting offers a sustainable solution for recycling organic waste, with nitrous oxide (N2O) being a crucial greenhouse gas emitted during the preparation and application of vermicompost, contributing to nitrogen (N) loss. However, the extent of N2O emissions under different environmental conditions remains uncertain. This study aims to review the literature and evaluate the relationship between N2O emissions during two phases of vermicomposting and various substrate properties, including substance type, substrate C: N ratios, pH, and soil moisture content. The purpose of this review is to evaluate the significance of vermicompost in the reduction of environmental loads within the preparation and application processes of vermicomposting. Vermicomposting can also be utilized together with conventional composting process to enhance nutrient cycling rate and mitigate ammonia emissions. The findings from the literature showed that N2O emissions were higher during the preparation phase, as compared to the application phase of vermicomposting. In addition, the N2O emissions were dependent on the C: N ratio of the substrates, which in turn influences the nitrification and denitrification processes. The earthworms facilitate nitrogen removal via various mechanisms occurring within their digestive tracts, including denitrification. Overall, vermicomposting is an eco-friendly technology to lessen environmental loads, particularly NH3 and N2O emissions during its preparatory and application phases, i.e. providing the optimal C: N ratio of the substrates required for plant growth and ensuring soil health.