Vario max cube cns analyzer

The soil was collected from a crop field in Wólka Wojsławska, Zduńska Wola district, Łódź voivodship, Central Poland (51°38′45.169″N, 18°56′14.582″E). The soil was obtained using a manual composite technique in which soil samples were taken from random sites within the area, and then, six to eight subsamples were mixed thoroughly in the laboratory.
The C, N and S concentrations were analyzed using an Elementar Vario MAX cube CNS analyzer. The total concentration of the macroelements Na, Mg, Ca, K, P, Na and of the heavy metals Fe, Mn, Ni, Cr, Zn, Pb, Cd were assessed using the ICP-OES method (atomic emission spectrometry in inductively coupled argon plasma) on an Optima 7300DV system (Perkin-Elmer). The bioavailable forms of phosphorus and potassium were assayed according to Egner-Reihm. The soil reaction was determined potentiometrically either in a suspension of water, or 1 M KCl solution. Note, however, that 1 M KCl simulates the soil solution better than water (Goulding, 2016 (link)). The general physicochemical parameters of the soil are presented in Table 1.

At the end of this experiment, 10 seedlings per treatment (one seedling per pot) were collected and divided into roots, stems and leaves. Their DW was measured after being dried at 70°C for 48 h. There were 10 replicates per treatment.
For the assays of S, Al and P in roots and leaves, fully expanded mature (about 7-week-old) leaves (midribs and petioles removed) and fibrous roots were collected after the seedlings were washed thoroughly with tap water and given a final rinsing with deionized water, then dried at 70°C for 48 h. These dried samples were ground to pass a 40-mesh sieve. S was assayed with the vario MAX cube CNS analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Al and P concentrations were measured according to Hsu (1963) (link) and Ames (1966) (link), respectively after the powdered samples were digested in a mixture of HNO₃ : HClO₄ (Yang et al., 2012 (link)). There were four replicates per treatment.
Root total soluble proteins were extracted with 50 mM Na₂HPO₄-KH₂PO₄ (pH 7.0) and 5% (w/v) insoluble polyvinylpyrrolidone. Total soluble proteins in the extract were assayed according to Bradford (1976) (link). There were four replicates per treatment.