Fig. 2: Mycorrhizal growth response over 3 yr.

MGR varied widely, ranging from −12 to +40%. Plot shows mean values (circle), as well as the confidence interval of MGR for each field (n = 8 independent control and inoculated plots). Significant differences are highlighted by filled circles. High- and low-MGR fields (75th and 25th quantiles) are highlighted by shaded areas and bold x-axis labels. We observed a slight year effect. 2019 was the year with the lowest number of fields with significant positive effects (4 out of 25 fields, 16% of fields) and 2020 was the year with the highest number (5 out of 12 fields, 41% of fields). This could be due to different weather conditions during the 3 yr.