## 2 Materials and Methods
### Fatty Acid Methyl Ester (EL-FAME) Analysis  
Microbial community structure was determined using the ester-linked fatty acid methyl ester (EL-FAME) analysis method by [PERSON] and [PERSON] [38]. The EL-FAME method was performed following four steps: (1) saponification and methylation of ester-linked fatty acids by incubation of 3 g of soil in 15 mL of 0.2 M KOH in methanol at 37 \({}^{\circ}\)C for 1h, during which time the samples were vortexed every 10 min, and at the end of the incubation, 3 mLs of 1.0 M acetic acid was added to the mixture to neutralize the pH; (2) the FAMEs were partition into an organic phase by adding 10 mL of hexane followed by centrifugation at 480\(\times\)\(g\) for 10 min; (3) the hexane layer was transferred to a clean glass test tube, and the hexane evaporated under a stream of N\({}_{2}\); and (4) the FAMEs were dissolved in 300 \(\upmu\)L of 1:1 hexane:methyl-tert butyl ether containing a 19: 0 internal standard (methyl nonadecanoate acid) and transferred to a gas chromatography (GC) vial for analysis. Using this protocol, the extracted FAMEs were analyzed in a Agilent 7890B GC Series (Wilmington, DE, USA) equipped with a flame ionization detector and a fused silica capillary column (25 m \(\times\) 0.2 mm) using H\({}_{2}\) (ultra-high purity) as the carrier gas. The temperature program was ramped from 170 \({}^{\circ}\)C to 250 \({}^{\circ}\)C at 5 \({}^{\circ}\)C min\({}^{-1}\) as previously done by [PERSON] et al. [20]. Fatty acids were identified and quantified by comparison of retention times and peak areas to components of standards. FAME concentrations (nmol g\({}^{-1}\) soil) were calculated by comparing peak areas to an analytical standard (19:0, Sigma Chemical Co., St. Louis, MO, USA) calibration curve, which was used to calculate molar percent (mol %). The FAMEs are described by the number of C atoms, followed by a colon, the number of double bonds, and the position of the first double bond from the methyl (\(\upomega\)) end of the molecule. Cis isomers are indicated by c, and branched fatty acids are indicatedby the prefixes i and a for iso and anteiso, respectively. Other notations are Me for methyl, OH for hydroxyl, and cy for cyclopropane. Twenty-six fatty acids (FAME) consistently present in the samples were used for the data analysis, with fourteen of the twenty-six FAMEs representing different bacterial and fungal biomarkers [39; 40; 41; 42]. FAMEs with a carbon chain length of 14 and higher were used to calculate total FAME (nmol g\({}^{-1}\) soil), which is used to estimate microbial biomass and community structure in agricultural soils. Different FAME profile indicators were used to represent saprophytic fungi (SaproFung), (i18:0, 18:1\(\omega\)5c, 18:1\(\omega\)6c, 18:1\(\omega\)7c, 18:1\(\omega\)9c, 18:2\(\omega\)6c, 18:3\(\omega\)6c), arbuscular mycorrhizal fungi (AMF), (16:1\(\omega\)5c), gram-positive bacteria (GP), (i14:0, a14:0, i15:0, a15:0, i16:0, a16:0, i17:0, a17:0, a19:0, a19:0), gram-negative bacteria (GN), (cy17:0\(\omega\)6c, cy19:0\(\omega\)7c), and actinobacteria (10 Me16:0, 10 Me17:0, 10 Me17:1\(\omega\)7c, 10 Me18:0, 10 Me18:1\(\omega\)7c, 10 Me19:1\(\omega\)7c). Total bacteria was calculated based on the summation of the abundance of gram-positive, gram-negative, and actinomycetes biomarkers. The fungal sum was calculated based on the total sum of saprophytic fungi (SaproFung) and AMF biomarkers. The fungal/bacterial (F:B) ratio was calculated by dividing the fungal sum by the bacterial sum. Microbial stress indicators, including FAME ratios of cyclo 17:0 to its precursor 16:1\(\omega\)7 (cy:pre), SaproFung to total bacteria (SF:TB), and AMF to bacteria (AMF:TB), were calculated as previously done to evaluate conservative management by [43]. The [PERSON]'s diversity index [37] was calculated as follows:  
\[\mathrm{H}^{\prime}=-\ \sum_{i=1}^{26}pi*(\ln pi)\]