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Description
Determination of soil properties: All soil samples underwent air-drying, and soil water content (SWC) was assessed through weight measurements. Soil pH and EC were ascertained using a pH meter (SevenExcellence-S470, Mettler-Toledo, Columbus, OH) following extraction at soil-to-deionized water ratios of 1:2.5 and 1:5 w/v, respectively. Total soil salts were quantified utilizing the weight method (Bado et al., 2016). Soil total organic carbon (SOC) content was determined via dichromate oxidation and titration with ferrous ammonium sulfate (Gul et al., 2015). The total N (TN) content was measured by a semi-micro Kjeldahl digestion procedure, soil available phosphorus (AP) and available potassium (AK) contents were determined by digestion with H2SO4 and HClO4 followed by extraction with 0.5 mol L-1 NaHCO3 (Bi et al., 2020). AK and AP were assessed using inductively coupled plasma-optical emission spectrometry (ICP-OES, Optima 5300DV, Perkin Elmer, Waltham, MA). Major cations (Na+, K+, Mg2+, and Ca2+) and anions (Cl-and SO42-) were identified through ion chromatography (IC, 886 Basic Plus, Metrohm AG, Herisau, Switzerland) with a detection limit of 0.02 mg L-1. Soil DNA extraction and sequencing: Total genomic DNA was extracted utilizing the Omega Soil DNA Kit (M5636-02, Omega Bio-Tek, Norcross, GA) following the manufacturer’s protocol. The quantity and quality of the extracted DNA were evaluated using a NanoDrop NC2000 spectrophotometer (Thermo Fisher Scientific, Waltham, MA) and agarose gel electrophoresis, respectively. The ITS1 region of the fungal rRNA gene was amplified employing the forward primer ITS5F (5ʹ-GGAAGTAAAAGTCGTAACAAGG-3ʹ) and the reverse primer ITS2R (5ʹ-GCTGCGTTCTTCATCGATGC-3ʹ). To facilitate multiplex sequencing, sample-specific 7-bp barcodes were incorporated into the primers. Following amplification, PCR products underwent purification using Vazyme VAHTSTM DNA Clean Beads (Vazyme, Nanjing, China) and quantified with the Quant-iTPicoGreen dsDNA Assay Kit (Invitrogen, Carlsbad, CA). Post-individual quantification, the amplicons were evenly pooled, and pair-end 2 × 250-bp sequencing was executed on the Illumina NovaSeq platform utilizing the NovaSeq 6000 SP Reagent Kit (500 cycles, Illumina, San Diego, CA) at Shanghai Personal Biotechnology Co., Ltd., Shanghai, China.