deletions | additions       diff --git a/From_lab_to_field_Although__.md b/From_lab_to_field_Although__.md  index 05ff435..99b3be1 100644  --- a/From_lab_to_field_Although__.md  +++ b/From_lab_to_field_Although__.md 
...
  Due to the slow kinetics of soil mineral weathering, and the complex soil matrix, a direct estimation of the contribution of mycorrhizal fungi on the weathering process is challenging.  Three different approaches have been adopted to address the impact of mycorrhizal weathering: 1) historical weathering markers, 2) stable isotopes to trace the source of tree nutrients and 3) quantifying incubated minerals in contrasting soils.  Tunnels, as described in \cite{Jongmans_1997} are the only quantifiable fungal markers of weathering that remain visible over geological time. Unfortunately, fungal tunneling either reflects only a small portion of the total effect of fungi on the weathering process, or the fungal impact is negligible, as tunneling contributes less than 0.5% tot total mineral weathering\cite{Smits_2005}.   Stable isotopes of especially Ca and Sr have been used extensively to source the origin of Ca in drainage water .   Applied to plant tissues, it could potentially traceback the source of plant nutrients back to the soil.