Apparent electrical conductivity as a tool for earthworm parameters evaluation in a commercial orchard

Non-invasive geophysical methods, such as EMI (Electromagnetic Induction), are innovative tools to study soil biological parameters. This work was carried out to assess correlations between soil earthworm abundance and biomass and soil apparent electrical conductivity (ECa) measured by means of a Profiler GSSI EMP-400. The trial was performed in a 1-hectare commercial peach orchard characterized by a clay loam soil. Mustard method combined with hand-sorting technique were used to sample earthworms in areas (1 x 1 m) falling in cover cropped (CC) and chemically weeded (CW) strips. Statistically significant linear relationships were found between ECa, measured at 13 kHz, and earthworm biomasses in both CC and CW strips (R2 >0.72). Instead, abundance earthworm showed relations only in CW strips (R2 >0.50). EMI technique seems to be a very efficient tool to locate representative soil sampling areas and spatialize earthworm parameters at field level.