Enhancing infiltration characteristics of compact soil in open-pit dumps through arbuscular mycorrhizal fungi inoculation in Amorpha fruticosa: Mechanisms and effects

Abstract

Soil infiltration performance is a critical factor in the ecological restoration of waste dumps within arid and semi-arid regions. While the significance of arbuscular mycorrhizal (AM) fungi in influencing soil structure has long been acknowledged, the precise mechanism by which these fungi affect the infiltration performance of compacted soil in waste dumps remains elusive. This study, conducted over 4 years in an open-pit dump, examined the impact of artificially inoculated AM fungi on Amorpha fruticosa roots, soil porosity, and soil infiltration performance. We aimed to elucidate this intricate relationship through field infiltration tests and quantitative imaging technology. Our findings revealed that the development of A. fruticosa root significantly enhanced the soil infiltration performance and soil pore structure in the vicinity of the roots. Moreover, inoculation with AM fungi significantly improved root density characteristics, altered root morphology, and increased the average root diameter. The synergistic effect of mycorrhiza and fungi reduced the number of soil pores while increasing their mean volume and altering their geometry. Roots played a pivotal role in soil pore connectivity, with mycorrhiza and fungi significantly increasing the equivalent diameter of connected pores and the complexity of the pore network. Furthermore, inoculation with AM fungi indirectly influenced soil macroscopic pore parameters by altering root morphology. These changes in root morphology, along with alterations in soil macroscopic pore parameters, directly enhanced soil infiltration capacity. In summary, our study demonstrated that the artificial inoculation of AM fungi in open-pit dumps within arid and semi-arid areas promoted plant root growth, enhanced soil pore development, and improved soil infiltration. These findings underscored the significance of AM fungi in ecological restoration efforts.