Carbon sequestration and soil responses to soil amendments - A review

The recent increase in climate change that results in varying weather conditions and climate change scenarios has necessitated an urgent need to address the situation using a nature-based solution approach. Soil is a major source and sink of carbon, and any approach that could enhance its carbon sequestration potential could aid in climate change control through reducing carbon emissions. One of these nature-based solutions is the use of organic amendments. Most organic amendments serve as a source of beneficial microbes, nutrients, and carbon for replenishing soil carbon stock and enhancing soil biological and biochemical processes. Thus, they are essential in maintaining soil biodiversity, promoting crop yield, and contributing to soil carbon sequestration. Harnessing organic amendments in soil carbon sequestration has led to using various organic materials such as biochar, animal manure, plant litter, coal gangue, and straw to enrich soil carbon stock. However, there are limitations regarding their consistency and efficacy under field and laboratory conditions. In this review, we explore soil organic carbon sources and compositions, soil amendments, priming and carbon sequestration, soil amendments in microbial selection and carbon sequestration, soil amendments in driving below-and-aboveground soil carbon sequestration processes, and the limitations of soil amendments to carbon sequestration. We further discuss the research gaps that will enhance our understanding of carbon sequestration and soil responses by leveraging a nature-based approach for controlling soil carbon emissions and improving soil carbon sinks.