Flash ea1112 analyzer

The plots were sampled in October 2014, 6 months after amendments were applied, as the turf was re-greening and undergoing active growth. Topsoil cores from the upper 0–15 cm depth were collected randomly with a 2.5 cm diameter probe at three points within each replicate plot, then composited. The samples were preserved in polythene bags and brought to the laboratory within a half hour after sampling. Root debris was removed. For physicochemical analysis the air-dried soil was ground to pass a 2 mm sieve before analysis and were stored and room temperature. For microbial analyses, fresh soil samples were kept at -80°C until DNA and PLFA extractions were performed. Gravimetric soil water content (SWC) was determined by the procedures of Gardner et al. [31 ]. In brief, soil samples were weighed, oven-dried (105°C), cooled (25°C) and then reweighed. The soil pH was analyzed in soil:water (1:5) suspension [32 ]. The soil total carbon (TC) and nitrogen (TN) contents of the biochar samples were determined using CNS on a Flash EA1112 analyzer (Thermo Scientific).

For each tree, at least 10 leaves were composited for analysis, avoiding leaves with evidence of disease, herbivory or damage from buckshot. Leaves were oven-dried at 60 °C to constant mass and ground in a Wiley mill to pass a 40-mesh screen. Carbon and N concentrations were determined through combustion in a CN elemental analyzer (FlashEA 1112 analyzer, Thermo Scientific). Concentrations of P, Ca, Mg, and K were determined by dry ashing ∼0.25 g of ground sample at 470 °C in a muffle furnace and digesting on a hot plate with 5 or 10 mL of 6N HNO₃ (Siccama et al., 1994 (link)). The digests were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES; Optima 5300 DV, Perkin-Elmer). One blank, two replicates of standard reference material (NIST 1515 or arginine), and one duplicate sample were processed with each group of 30–40 samples. An in-house quality control followed by a blank was run after every 10 samples, and the machine was recalibrated if >5% drift was observed in the in-house standards. Errors were generally <5% (Hong et al., 2021 (link)).

X-ray diffraction (XRD) analysis was carried out using a D8 Advanced Bruker anode X-ray diffractometer (Bruker, Billerica, MA, USA) with Cu Kα (λ = 1.5406 Å) radiation. The morphology of the synthesized samples was characterized by scanning electron microscopy (SEM) (JSM-600F, JEOL, Tokyo, Japan). Transmission electron microscopy (TEM) images were obtained using a JEM-2100F (JEOL, Tokyo, Japan). Infrared (IR) spectra of the samples were recorded using an IR Prestige-21 spectrophotometer (Shimadzu, Tokyo, Japan). The TGA was carried out on a SETRAM LABSYS TG system under air flow with a heating rate of 10 °C·min⁻¹. X-ray photoelectron spectroscopy (XPS) was conducted by a Theta Probe AR-XPS system (Thermo Fisher Scientific, Waltham, MA, USA). Elemental analysis (EA) was determined with a Flash EA 1112 analyzer (Thermo Fisher Scientific, Waltham, MA, USA).