deletions | additions       diff --git a/From_lab_to_field_Although__.md b/From_lab_to_field_Although__.md  index 16a9ca7..fcc3d7d 100644  --- a/From_lab_to_field_Although__.md  +++ b/From_lab_to_field_Although__.md 
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Although numerous experiments clearly show that (mycorrhizal) fungi do have an impact on mineral dissolution (see previous section), the significance of mycorrhizal weathering on soil and global scale weathering rates remains controversial. This ongoing controversy is caused by both the challenge to quantify the mycorrhizal contribution in the field, and a series of persisting misconceptions. Modelling is a useful tool to test the scope of mycorrhizal weathering concepts. In this section we will review the available field data and modeling work on mycorrhizal weathering, and discuss the most persistent misconceptions in this research field.    Without doubt does vegetation have a substantial positive effect on soil mineral weathering . \cite{Berner_1992}.  It remains the question though, how much influence the associated mycorrhizal fungi have on this vegetation effect.  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. 
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Apatite is a calcium-phosphate mineral, and as P has no stable isotopes, the uptake dynamics can only be studied via the Ca ion (or potentially the ¹⁸O/¹⁶O in the phosphate group .  As apatite is generally only a minor mineral in the soil mineral matrix, its contribution to the soil solution Ca pool is minor compared to other minerals.  If the Ca isotopes in the plant is more similar to the signature in apatite than in the soil solution, it indicates that the plant takes up Ca directly from the apatite crystal. Which is below the root scale, indicating a selective uptake via mycorrhizal hyphae colonizing apatite grains.   In an influential paper Blum *et al.* \cite{Blum_2002} used applied  this technique to compare technique, but as in their study area,  theplant-Ca source of  different tree species with contrasting mycorrhizal associations.  As mineral sources did have similar Ca isotope ratios, they used the ratio between Ca and Sr instead.