Metabolomic and Lipidomic Analysis of Soil Rewetting

Statistical analysis of metabolomics and lipidomics data was performed using the pmartR package [48 (link)] with R version 4.0.2 [49 ]. Data were log2-transformed and normalized via global median centering. Statistical comparisons were performed for each time point after soil rewetting (10, 20, 30, 90,180 min) back to the dry 0-min soil group using ANOVA with a Dunnett test correction [50 , 51 (link)]. For each lipid and polar metabolite, these adjusted p values and the mean log2 fold changes for each of the above comparisons are reported (Supplementary Tables S2 and S4), along with the number of observations per group. Lipid ontology enrichment [47 (link)] was used to extract biological information from the lipid name, highlighting significant trends in lipid categories, lipid class, sub-class, fatty acyl chain characteristics, total number of fatty acid carbons, and double bonds (Supplementary Table S3). Enrichment analysis was done separately for subsets of lipids that were significantly more abundant in either dry soil or wet soil to uncover significant shifts with change in soil moisture.