Fertimetro as a tool to assess the relative effects of organic matter and earthworms in vineyard soils

Soil fertility is crucial for sustainable agriculture and the health of terrestrial ecosystems. Earthworms and bacteria play key roles in creating fertile soils due to their role on organic matter (OM) dynamics and soil structure. This work focuses on the interaction between earthworms and microbial communities in the soil. Understanding these relationships is essential for deepening knowledge about earthworms and developing soil management strategies to enhance fertility. Experiments were conducted at INRAE Avignon under laboratory and field conditions to examine the contribution of various earthworm species and different types of OM on microbial activity. The analytical tool used was the Fertimetro, patented (WO2012140523A1) by the University of Padova, which quantifies microbial activity and plant nutrients deficiency by measuring the degradation of cotton and silk threads in plain or pre-treated versions with nitrogen, or phosphorus and potassium, which are buried for seven days into the soil. Through their use, we aimed at verifying whether different species of earthworms and OM inputs could confer differences in thread degradation, and to possibly speculate on how this could be interpreted in judging soil fertility as well as the efficiency of its ecosystem services. The results highlighted that in laboratory conditions, the presence of OM and, in some cases, earthworms can vary the fiber-degrading activity of soil microbes. Furthermore, some preferences of the different ecological categories for some OM conditions could be observed. In the field, higher microbial activity was measured over time in both inoculated and control conditions. Variations in microbial activity are hypothesized to be due to earthworm presence in particular conditions. The study showed the effectiveness and the potential of Fertimetro in soil analysis providing valuable insights. Fertimetro can be a valid analytical tool, if based on the study context, for studying earthworms and their interaction with soil and organic matter components, and it can be used to further understand interactions among soil organisms.