**5. Overall Perspective: Found and Missing Pieces of the Proposed Conservation Strategy Puzzle**

The use of plant-based amendments with high C/N ratios as a conservation strategy in cultivated peatland is still in its infancy. This field study over one lettuce growth cycle examined the effects of such amendments in a real farming situation to evaluate the potential use of this conservation practice for sustainable vegetable crop production on cultivated peatlands. Although the pieces of the puzzle are starting to fit into place [11,12,19,20], this first field study revealed that some important information is still missing. Using PRS® probes under field conditions, this study confirmed that the main impact on crop growth resulting from the incorporation of miscanthus straw and willow chips is linked to N availability, with a consequent reduction in fresh lettuce yield. The plant N uptake index indicated how miscanthus and willow amendments can impact N uptake by the lettuce crop, pointing toward the need for fertilization adjustments under this conservation strategy.

As for the missing pieces, a number of unanswered questions remain with regard to optimizing the application of such amendments, such as the optimal time (fall versus spring) of application, the effects of combining this strategy with other conservation strategies such as cover crops (for example, a fall application of the amendment together with a cover crop), the effects of composting miscanthus straw and willow chips before incorporating them in the soil, and also the possibility of using these plant-based amendments as a mulch for the first year before incorporating them into the soil. Additional work is also needed to investigate the effects of consecutive years of soil amendment on different vegetable crops and in different types of cultivated peatlands to confirm and generalize the findings of the present study. Future field studies should also explore the long-term carbon dynamics in peatland amended with plant-based, high-C/N-ratio amendments under real field conditions to determine if this strategy could offset annual C losses and ensure muck soil conservation for generations to come.

**Author Contributions:** Conceptualization: J.D.-R.; methodology, J.D.-R. and A.G.; formal analysis, J.D.-R. and A.G.; investigation, A.G.; resources, J.D.-R. and J.C.; data curation, J.D.-R. and A.G.; writing—original draft preparation, J.D.-R. and A.G.; writing—review and editing, J.D.-R., A.G. and J.C.; visualization, J.D.-R.; supervision, J.D.-R. and J.C.; project administration, J.D.-R. and J.C.; funding acquisition, J.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** We would like to acknowledge the financial support of the *Natural Sciences and Engineering Research Council of Canada (NSERC)* through a *Collaborative Research and Development Grant* in partnership with *Productions Horticoles Van Winden Inc.*, *Les Fermes Hotte et Van Winden Inc.*, *Maraîchers J.P.L. Guérin et fils Inc.*, *Delfland inc.*, *Vert Nature Inc.*, *Isabelle Inc.*, *La Production Barry Inc.*, *Le Potager Montréalais ltée.*, *Les Jardins A. Guérin et fils INC.*, *Les Fermes du Soleil Inc.*, *Les Fermes R.R. et fils inc.*, *Productions Maraîchères Breizh Inc.*, and *R. Pinsonneault et fils ltée*.

**Institutional Review Board Statement:** Not applicable.

**Acknowledgments:** We would like to acknowledge Moranne Béliveau, Charles Gauthier-Marcil, Simon Corbeil and Nicolas Shooner, who helped with the field study, particularly the cleaning of the resin probes.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Sample Availability:** Samples of the compounds are not available from the authors.
