THE INFLUENCE OF FERTILIZER SYSTEMS ON YIELD DIFFERENCES IN THE FIRST THREE YEARS OF THE MELIORATION OF A SOIL UNDER CONTROL POLLUTED BY CRUDE OIL FROM ORADEA, ROMANIA PUBLISHEDNicu-Cornel SABĂU, Maria ŞANDOR, C. DOMUŢA, R. BREJEA
The paper presents the partial results of researches regarding the agrochemical melioration of soils under control polluted by crude oil, brought from the exploitation site at Suplacu de Barcău that took place at the Agricultural Research and Development Station in Oradea, Bihor County. The researches have like objective the study of fertilizer systems influence on millet-hay yield differences between non polluted and polluted variants, in the first tree years of melioration process. The experimental device was made out of 1 m 2 micro parcels, spread out in subdivided parcels, in four repetitions, having three factors: A - the pollution by crude oil from Suplacu de Barcău, in two graduations a1-nonpolluted and a2-under control polluted with 3 % crude oil concentration; B – the organic fertilization with manure (0, 50, 100 and 150 to/ha) and C – the mineral fertilization with complex fertilizer in the doses: N 0 P 0 K 0 , N 100 P 80 K 70 , N 200 P 160 K 140 and N 300 P 240 K 210. The experience was set out on a haplic luvosoil in the year 1993 and the soil was cultivated with millet in the first tree years and with spring wheat in the last seven years of research. Taking in consideration that în this work, we analyze the yield differences of millet-hay, between the not polluted (control) and polluted with 3 % crude oil variants, (a1-a2) the experiment can be considered with two factors: factor B – organic fertilizer and factor C – mineral fertilizer. The best results in the agrochemical melioration process of soils under control polluted with 3 % crude oil, in the first three years of experiment are obtained for the bigger manure quantity (7,5 q/ha) and medium of complex fertilizer doses, 5,36 q/ha for N 100 P 80 K 70 and 5,56 q/ha for N 200 P 160 K 140 . The shape of surface response of average yield differences shows that in the case of organic fertilizer system, the yield differences increases at once of manure quantity increasing, while in the case of complex fertilizer doses applied was registered a maximum of these for the medium doses. For the variants without complex fertilizers administrated the smaller yield differences are obtained by the variants with 50 t/ha manure (3,17 q/ha) and 100 t/ha manure (3,56 q/ha) while in the variant without organic fertilization, by variant with maximum complex fertilizer dose N 300 P 240 K 210 (2,62 q/ha) The agrochemical melioration of polluted soils with small concentration of crude oil (3 % on ploughed layer) consists in the application of small quantity of manure, (50 t/ha) for the microorganisms inoculation and a big dose of mineral fertilizers with nitrogen (N 300 P 240 K 210 ) for the balance of C/N report .