The plant-based test, hereafter called the biotest, enables estimation of the environmental bioavailability of trace elements to plants either basically as concentration in shoots and roots or in a more integrative way as the net uptake flux in plants. The biotest procedure includes two successive steps: (i) a pre-growth of plants in hydroponics and (ii) a growth of plants in contact with soil samples. The concentration in shoots and roots as well as the net uptake flux of trace elements in plants are determined at the end of the second step of the biotest procedure.
This biotest is applicable to the assessment of environmental bioavailability of trace elements to plants, more particularly agricultural plants, in soils or soil materials under oxic conditions, considering that:
- Three plant species (cabbage, Brassica oleracea; tall fescue, Festuca arundinacea; tomato, Lycopersicon esculentum; see 7.1) are suggested in the standardised biotest procedure, but additional target-plant species can also be used (see Annex A),
- The standardised biotest procedure is validated for a range of trace elements including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn), but additional trace elements can be also accounted for (see Annex A).
The application of this biotest to soils and soil materials includes soils amended before or after field sampling with composts, sludges, wastewaters and other (waste) materials.