Microbial aggregates and functional materials for mitigating soil nitrogen loss: a review

Abstract

Nitrogen (N) plays a critical role in crop growth, development, and yield. In global agriculture, however, about 40 to 60 percent of nitrogen applied to soil is lost through nitrous oxide (N2O) emissions, nitrate (NO3−) leaching, and ammonia (NH3) volatilization, resulting in significantly reduced crop yields and environmental issues, such as water body eutrophication, soil degradation, and increased greenhouse gas emissions. While a range of mitigation strategies have been explored, effective and scalable solutions that simultaneously enhance N retention in soil and promote crop uptake remain limited. In this context, integrated approaches that combine microbial aggregates with functional materials represent a promising yet underexplored pathway. This review examines the structural functions of microbial aggregates and the properties of common functional materials, emphasizing their mechanisms of action in reducing soil nitrogen loss and their potential contributions to mitigating environmental pollution. Additionally, the physical, chemical, and biological interactions during the synergistic application of these technologies were investigated, resulting in a 14–26% increase in soil nitrogen retention and a 15–35% increase in crop yields through improved inter-root nitrogen supply. This review aims to provide practical strategies for reducing agricultural nitrogen loss and its associated environmental hazards while promoting sustainable agricultural practices.