The paper presents the results of the researches carried out at the Agricultural Research Station Oradea, Bihor County, between 1994 and 2002, regarding millet and wheat yields from a haplic luvosoil polluted under control with oil brought from the exploitation site at Suplacu de Barcău.
Phytoremediation is a recent technology that is used to stabilize or remove wastes from soils, groundwater or other medium by using living plants.
The experimental device was made out of micro parcels of 1 m², set up in a randomized manner, in a Latin square, polluted with a concentration of: 0, 1, 3, 5 and 10 % (0, 3, 9, 15, and 30 l/m²), oil in the ploughed layer, in four repetitions.
The experience was than cultivated with in the first three years with millet (1993-1995), a plant that is considered to be resistant to pollution, and than until 2002 with spring wheat. The tendency of relative yields of polluted plots show that in the time of research period of ten years, the pollutant was phyto degraded, without any ameliorative measures.
For the plot variants polluted with different concentration of crude oil, between the relative yields and time of research period was established second degree polynomial correlations, distinct and very significant statistically.
The shape of the curves indicates the fact that after a minimum of relative yields, registered in the first or the second year of research period these increases continuously in time, until the finish of the experiment.
The intensity of soil pollution, in the last year of research period, using the yield losses, in the plots with 1 % oil concentration is unpolluted, in the plots with 3 % oil concentration is weakly polluted, in the variant plots with 5 % oil concentration is moderate polluted and respectively in the plots with 10 % oil concentration is yet strong polluted.
The time of phytodegradation, evaluated with help of equations, through the condition for relative yields to be 95 %, when the soil pollution characterization became unpolluted results that: on the 1 % variant the soil became unpolluted after 5,4 years, on the 3 % after 7,8 years, on the 5 % variant after 9,6 years, and on the 10 % variant the soil became unpolluted after 10,8 years.