Mycorrhiza : Restoration of soil functions with the help of arbuscular mycorrhiza

Arbuscular mycorrhizal fungi (AMF) are a widespread group of soil fungi forming symbiotic associations with many plants, including crops. AMF can provide several soil ecosystem services. Recent studies indicate that soil management intensification reduces AMF diversity. Pot experiments showed that these reductions can impair plant productivity and ecosystem functioning, but field evidence is lacking. It is still unclear whether the functioning of arable soils with impoverished AMF communities can be increased or restored by re-introducing specific AMF species that complement the resident community.

The aim of the project was to monitor AMF communities in Swiss arable soils and to identify factors affecting their abundance and community composition. The team also intended to investigate whether the introduction of AMF into impoverished AMF communities can restore specific soil functions and whether AMF diversity can enhance ecosystem sustainability. In close collaboration with two other NRP 68 projects (“Nematodes” and “Soil bacteria”), the researchers tested whether different groups of beneficial soil organisms can complement each other and improve plant health and performance.

The team developed a sequencing-based method to assess AMF community composition at the species level in the field. It was shown that some AMF taxa can act as bioindicators for organic farming practices. The method also made it possible to trace inoculated AMF species. AMF inoculation into field soil enhanced clover biomass, but its effect on maize and wheat yield was generally weak.

The new sequencing method greatly increases our understanding of AMF biogeography and communities in field situations. The field and greenhouse experiments provide important information on the potential and factors determining the success of introducing AMF to arable soils and the effects of AMF diversity on plant productivity and ecosystem services.

The project offers new insights into the beneficial role of AMF. This is described in a leaflet. Tools for improving sustainable agriculture by means of appropriate soil management and stimulation of soil biota and soil biodiversity are presented.

Recruitment limitation in soil? Restoring soil ecosystem functioning and sustainability by introducing below ground mutualists