2.2. Analysis of physical and chemical parameters of wastes and soil
substitutes
The content of dry matter (DM) in wastes and soil substitutes was
determined by the gravimetric method by drying samples to constant
weight at 105°C. The amount of organic matter (OM) in the samples was
determined by measuring of the loss-on-ignition of dry matter at
550oC. Total ash was assessed by incinerating the
respective samples at 815oC followed by weighting the
post-combustion residues.
The content of macronutrients, i.e. Ca, K, Mg, P and Na were assayed by
means of X-ray fluorescence method with wavelength dispersion WDXRF
(Rigaku ZSX Primus, Inc., Wilmington, USA). The content of trace metals,
i.e. Cd, Cr, Cu, Ni, Pb and Zn were determined by inductively coupled
plasma atomic emission spectroscopy method (ICP-OES) after sample
digestion in aqua regia (Perkin Elmer Optima 5300, Perkin Elmer
Inc., Waltham, MA. USA). The total content of sulphur was determined
with infrared spectroscopy (IR) using a ELTRA CHS (Eltra GmbH, Haan,
Germany) whereas the content of nitrogen by the Kjeldahl method.
The wastes and soil substitutes were assayed for pH and electrical
conductivity (EC) were measured by photometric and conductometric
methods, respectively in aqueous solutions at the ratio 1:2.5 (w/v). A
sum up of selected waste parameters was provided in Table 2.
TABLE 2 Physical and
chemical characterization of wastes used for soil substitutes blends