A Comprehensive Review of the Effects of Organic Amendments on Soil Health and Fertility: Mechanisms, Greenhouse Gas Emissions, and Implications for Sustainable Agriculture

With the escalating application of chemical fertilizers, the potential for environmental pollution has increased significantly. Currently, the degradation of soil quality due to the indiscriminate use of chemical fertilizers poses a more pressing challenge than ever before, threatening both human food production and the environment. The utilization of organic amendments not only enables the efficient recycling of organic waste resources but also reduces the reliance on chemical fertilizers. Meanwhile, organic amendments play a crucial role in soil improvement, helping to stabilize and enhance crop yields. Numerous studies have investigated the impacts of organic amendments on various aspects of crop production, including soil biology, biochemistry, heavy metal accumulation, and greenhouse gas (GHG) emissions. However, these studies have predominantly focused on isolated aspects rather than adopting a comprehensive perspective. Therefore, a comprehensive analysis of the positive and adverse effects of organic amendments is important in optimizing fertilizer use to meet crop nutrient demands and advancing carbon-neutral agriculture. This study mainly explores the intrinsic mechanism of the influence of organic amendments on soil physicochemical properties, enzyme activity and microbial diversity, heavy metal contamination and mobility, and GHG emissions in farmland. Finally, recommendations for the future development of organic amendments are proposed for promoting green and sustainable agricultural practices.