Miranda M. Hart, Pedro M. Antunes, V. Bala Chaudhary and Lynette K. Abbott
Arbuscular mycorrhizal fungi (AMF) are root dwelling fungi that are marketed as biofertilizers to improve plant growth. Despite the increased use of AMF inocula by growers around the world, there is little evidence that they promote plant or soil health in all situations.
Research shows that inoculant success is mixed: there is evidence for improved plant response in some cases, but in many there is no change or even decreased plant performance. The reasons for this discrepancy aren’t clear, but may be related to the preponderance of studies using artificial growing conditions and the short time scale of most studies. Perhaps more concerning is that there are very few studies which show establishment success of the inoculant. Whether this means that inoculants fail to establish in most cases is not known, because few studies measure the abundance of the inoculated fungus.
If these inoculants do establish successfully in managed systems, there is no evidence that they can be controlled once released into a novel environment. Due to the generalist nature of commercial inoculants, there is good reason to believe that they could establish, and spread, far beyond the zone of intended use. What this means for soil ecosystems is not clear.
In this paper we discuss ecological and operational knowledge gaps, as well as possible negative consequences, surrounding the use of AMF biofertilizers.