Arbuscular mycorrhizal symbioses (AM symbioses), formed between Arbuscular mycorrhizal fungi (AMFs) and the majority (ca. 80%) of terrestrial plants, play an important part in the regulation of nutrient cycling in plant-soil systems. Owing to their potentially promising role in sustainable agriculture, AM symbioses have attracted increasing interest in the last decade. This review emphasized the functional interrelations among AM symbioses, soil free-living microbes, and the dynamics of carbon (C), nitrogen (N), and phosphorus (P) in plant-soil systems. The contribution of AM symbioses to plant P has become central to our understanding of AM symbiotic function over the past few decades. There is accumulating evidence that plant P uptake is bidirectionally regulated by AM symbioses. More specifically, plant P uptake is enhanced by AMF infection when the soil is P deficient, but when there is excessive soil P, its transfer to the plant is restricted and excessive P accumulates in hyphae, spores, or vessels. The ability of plants to take in P has been correlated with the volume of soil that their roots can explore. However, in the presence of AMF, mycorrhizal P uptake becomes the dominant pathway, even though plant growth or total P uptake may not be enhanced by the interaction. A benefit of AMF infection to plant P uptake is associated with carboxylate exudation produced by hyphae, which promote the mineralization and disaggregation of organic matter through enhancing the activities of phosphate-solubilizing bacteria. Comparatively, the effects of AMFs on N cycling are particularly complex since fungi are likely involved in all N processes. Arbuscular mycorrhizal fungi can take up both inorganic N and low-molecular-weight organic N from soil organic matter, which is primarily used by the fungus, with only a small amount being transferred to the roots. Arbuscular mycorrhizal fungi can also reduce N loss by regulating the trade-off between nitrification and denitrification, through reducing the concentrations of soil mineral N due to AMF uptake, improving rhizosphere aggregate stability, and decreasing the pH of soil subjected to AMF inoculation. Nitrogen loss as N₂O is reduced as well from the soil inoculation with exogenous AMF. The reduction of N₂O emissions is related to the shift of microbial community composition with the decrease of the microbial community responsible for N₂O production and the increase of those microbial groups responsible for N₂O consumption. Other soil microorganisms, including ammonia-oxidizing bacteria, can be suppressed by AMF infection, which also contributes to reduced N₂O production. Arbuscular mycorrhizal fungi can also be associated with other root symbionts such as root nodules. While the exact mechanisms remain unclear, it is generally believed that AMFs deliver nutrients (such as P) for N fixation in nodules or by enhancing the activity of rhizobia. Because of increasing concerns regarding global climate change, AMF contribution to soil C storage has attracted considerable attention in recent years. Whether AMFs facilitate soil C sequestration or induce soil C loss remains under debate. One proposed explanation is that if AMFs promote soil C storage, then this becomes a short-term liability through the stimulation of organic matter decomposition and acceleration of litter degradation, while the long-term benefits include the incorporation of organic matter into soil aggregates and increased litter production due to enhanced plant growth. The flux of nutrient elements in plant-AMF-soil systems are associated with the interactions between AMF and pertinent soil microbes. Arbuscular mycorrhizal fungi generally facilitate the growth of phosphate-solubilizing bacteria, rhizobia, actinomycetes, and ectomycorrhizal fungi (EMF), and the inoculation of actinomycetes also promotes the growth of AMF. However, rhizobia and EMF appear to suppress the colonization and growth of AMF when they arrive before AMF. The interactions between AMF and soil microbes can also be regulated by soil nutrient level, such as the case of low soil nutrient conditions, in which AMFs compete for soil nutrients with free-living soil microbes. Competition can also occur among different AMF taxa. Indeed, the biogeochemical cycles of C, N, and P are interlinked in plant-soil systems, where there is an interaction between free-living soil microorganisms and AMFs, but it is unknown to date how the interactions among soil organisms regulate biogeochemical cycles of soil macro elements. A combined technique that uses both microbiological and stoichiometry methods may be needed to explore this "mystical territory".