The Impact and Regulatory Mechanisms of Nitrogen Fertilizer on Soil Carbon Cycling

Abstract

Modern agriculture must increase production to meet the growing global demand for food. However, excessive use of nitrogen fertilizer has led to a series of environmental issues. The impact of nitrogen fertilizer on soil carbon cycling is of particular concern, as agriculture is a major global carbon reservoir, and soil carbon cycling is crucial for maintaining ecosystem functionality. Previous research indicates that nitrogen fertilizer not only affects soil carbon storage but also alters the structure and function of soil microbial communities, thereby influencing carbon decomposition rates. Nevertheless, the specific mechanisms underlying the effects of nitrogen fertilizer on soil carbon cycling remain elusive. This study aims to comprehensively and systematically analyze the impact of nitrogen fertilizer on soil carbon cycling and elucidate its regulatory mechanisms. Nitrogen fertilizer exerts complex effects on soil, potentially promoting organic carbon accumulation, yet under certain conditions, it may also lead to carbon losses, closely intertwined with its impact on soil microbial communities. Regional and seasonal variations in the response to nitrogen fertilizer highlight the intricate dynamics of soil carbon storage, emphasizing the need for a thorough spatiotemporal investigation. Nitrogen fertilizer also influences soil microbial diversity, resulting in the excessive enrichment of certain microbial populations, disrupting the balance of microbial diversity in the soil. Moderate use of nitrogen fertilizer stimulates soil microbial metabolic activity, whereas excessive use may lead to a decline in metabolic activity. The regulation of soil carbon decomposition rates involves soil enzyme activity and organic matter decomposition pathways, with moderate nitrogen fertilizer application promoting soil carbon cycling, while high concentrations may impede carbon decomposition pathways. In conclusion, nitrogen fertilizer management should be guided by scientific principles to avoid excessive use. Establishing a systematic monitoring system that considers soil nutrients, microbial communities, and other factors is essential for achieving sustainable nitrogen fertilizer use. This approach aims to promote sustainable agriculture, reduce the burden on ecosystems, and enhance soil health and carbon storage.