THE EFFECT OF SITES AND DIFFERENT LONG-TE RM FERTILIZATION ON AGROCHEMICAL SOIL PROPERTIES AND THE CONTENT OF SOME HAZARDOUS ELEMENTS IN SOIL

Long-term fertilization affects significantly agrochemical properties and production capacity of soils (Kristan, Skala, 1983a, b; Vrkoc et a l., 1990 and others). Generally speaking, the growth of inputs used in the system of management on soil induces a necessity to study and eva luate their potential negative impact on soil medium and subsequently on the quality of production. In 1991 in IOSDV trials (coordination of Prof. E. V. Boguslawskoi, Giessen, FRG) on three sites in the Czech R epublic (Tab. I) the combination of factors was carried out from selec ted treatments - organic fertilization (O) and manuring, fertilization by industrial fertilizers 0, N2PK and N4PK (Tab. II)- sampling of top soil (two three-year crop rotations: root crop - winter wheat - winter barley). P and K doses were applied each year and amounted to 35 and 85 kg K.ha(-1).year(-1). Liming was used only on the site at Lukavec u Pacova, always applied to a root crop, uniformly the whole plot. The effect of studied factors on a,grochemical soil properties and content s of hazardous elements (2M HNO3 extract) was evaluated by variance an alysis (Tabs IV and VI). Comparison with initial situation of soil sup ply with nutrients (before stand establishment) shows that the intensi ty of P and K fertilization applied resulted in more evident increase only in available P in Praha-Ruzyne (Tab. III). Significant increase i n available P and K on manured treatments was recorded on all sites - on average by 29% in P and by 40% in K (Figs 1 and 2). Decline of pH/K Cl with gradated intensity of fertilizing by industrial fertilizers wa s more marked on the site with cambisol at Lukavec u Pacova (5,28 agai nst 5.63) and on luvisol in Praha-Ruzyne (5.71 against 6.33); (Tab. II I). On the contrary, manuring was manifested by increased pH/KCl - on average of sites by 0.3 (Fig. 3). Differences in humus content (drop a fter root crop, higher values on fertilized treatments) were not stati stically significant (Tab. IV, Fig. 4). Significant differences were d iscovered only among sites (Tab. VI) by evaluating the contents of haz ardous elements (2M HNO3 extract). Average values mostly correspond wi th average values recorded for districts where experiment sites are lo cated, after the survey conducted by Penk (1989), and are deeply below the maximum admissible values for the CR (Decree of the Ministry of E nvironment No. 13/1994 to Act No. 334/1992). Significant interactions show a marked decline in Cd content on cambisol (Lukavec u Pacova) aft er liming (Fig. 5) and significantly lower values of Pb, Cd, Ni and Cu after sugar beet in luvisol (Praha-Ruzyne). On degraded chernozem the differences in values due to factors used were generally lowest. The above changes in pH/KCl which have a marked influence on mobilization of acceptable forms of hazardous elements in soil are considered to be a weighty finding (Sauerbeck, Luebben, 1991 and others). It can be pr esupposed that they can result (on some sites and when liming is absen t) in raised contamination of plant production also on soils anthropog enically less contaminated, e.g. Cd - regions considered as the so-cal led pure ones with respect to immission load found out by Petrikova (1 990).