Chnos elemental analyzer

Leaf litter C and N contents were studied using a CHNOS Elemental Analyzer (Elemental Analyzer, Elementar Analysensysteme GmbH). Leaf litter P and K were studied with an inductively coupled plasma optical emission spectrometer (ICAP 6300 ICP‐OES spectrometer, Thermo Scientific, Thermo Electron Corporation). Leaf litter lignin and cellulose contents were measured according to the acid‐detergent lignin (Wei et al., 2016 (link)). This method yields cellulose and acid‐detergent lignin, which has been referred to as AUR (acid unhydrolyzable residue), by calculating the weight remaining after washing litter with different reagents.

After the RS measurements at the selected sites were concluded, surface soil samples (0–20 cm) were placed in polyethylene boxes and taken to the laboratory. After air-drying at room temperature for at least two weeks, the field-moist soil samples were sieved through a 2-mm nylon sieve to remove the plant roots, coarse debris and sand. The soil bulk density at the soil depth of 0–10 cm was measured using a cutting ring (5 cm in both diameter and depth).
The soil pH was determined in a 1:5 (w/v) soil: water slurry using a pH meter (Sartorius PB-10, Sartorius, Germany). The soluble salt (SS) content was determined by gravimetric method. The microbial biomass carbon (MBC) was determined using the fumigation-extraction method^{62 (link)}. The SOC was analysed by potassium dichromate oxidation titration^{63 (link)}. The total nitrogen (TN) content was measured using an Elemental Analyser (CHNOS Elemental Analyzer, Vario EL, Elementar, Germany). The available phosphorus and available potassium were measured using the Olsen method and flame emission spectrometry, respectively.