Vario el macro cube

Litter bags were collected, and sediment removed, after which the fresh weight of litter (Wi) was measured. A portion of the samples was dried at 65°C to a constant weight, and water content (P) was measured. The mass residual rate of litter was then calculated (Zhang et al., 2019 (link)). The mass residual rate (%)=W_i^*(1-P)/W₀. Here, W₀ denotes the dry weight of the initial litter bag.
An elemental analyzer (vario EL/MACRO cube, Elementar Analysensysteme GmbH, Hanau, Germany) was used to measure total carbon (TC) and total nitrogen (TN) content in litter samples. Before measuring litter pH, litter water (1:20 mass/volume) suspensions were shaken for 30min (Fioretto et al., 2000 (link)). Heavy metal (Cu, Zn, Pb, and Cd) concentrations in the litter were measured using atomic absorption spectrometry (Agilent Technologies 200 Series AA, United States). Additionally, 3,5-Dinitrosalicylic acid colorimetry was used to measure litter sucrose and cellulase content; phenol-sodium hypochlorite colorimetry was used to measure urease content; potassium permanganate titration was used to measure catalase content; and the disodium phenyl phosphate colorimetric method was used to measure phosphatase content (Jia et al., 2019 (link)).

Soil water content (SWC) was determined by means of the drying method. An elemental analyzer (vario EL/MACRO cube; Elementar, Hanau, Germany) was used to measure total carbon and nitrogen content in soil (TC_Soil and TN_Soil) and litter (TC_Litter and TN_Litter). Soil pH was measured by potentiometric method. Shaking in a soil-water (1:2.5 w/v) suspension for 30 min and then rest. Soil particle size (PS) was measured by using Mastersizer 3,000 laser diffraction particle size analysis instrument (Malvern Co. Ltd., Malvern, UK). Soil heavy metals, which include As, Cd, Cu, Pb and Zn, were measured by Inductively Coupled Plasma-Atomic Emission Spectrometry (iCAP 6000; Thermo Fisher Scientific, Loughborough, UK). Potassium permanganate titration was used to measure catalase. 3,5-Dinitrosalicylic acid colorimetry was used to measure sucrase and cellulase, while phenol-sodium hypochlorite colorimetry was used to measure urease. Finally, iodimetry was used to measure polyphenol oxidase (Guan, 1986 ).

We collect the fresh litters on the surface at the end of plant growth seasons. Following this, fresh litter weight was measured. Portions of samples were dried at 65 ℃ to a constant weight, and the litter water content was then measured. An elemental analyzer (vario EL/MACRO cube, Elementar, Hanau, Germany) was used to measure total carbon (TC) and total nitrogen (TN) in litter samples. Litter water suspensions (1:20 mass/volume) were then shaken for 30 min prior to measuring litter pH [13 (link)]. Heavy metal (i.e., Cu, Zn, Pb, and Cd) concentrations in litter were measured using atomic absorption spectrometry (AAS) (Agilent Technologies 200 Series AA, Palo Alto, CA, USA). Additionally, 3,5-Dinitrosalicylic acid colorimetry was used to measure litter sucrase and cellulase content; phenol-sodium hypochlorite colorimetry was used to measure urease content; potassium permanganate titration was used to measure catalase content; the disodium phenyl phosphate colorimetric method was used to measure phosphatase content [11 (link)].