njemački

Stand von schweren Metallen und Atrazin in hydromelioriertem Pseudogley-Gley Boden

Soil of adequate quality is one of the main preconditions of an efficient agricultural production. The total soil area available on earth is limited and is getting smaller every day under the influence of the climate -erosion, spreading of deserts- and numerous human activities. High level of heavy metals and pesticides in agricultural soils may result from the overall pollution of the environment where the soil is located but it may also result from the application of certain agricultural practices -fertilization, plant protection, etc. The objective of the research conducted in the 1996-1998 period was to determine: 1. Levels -residues- of atrazine in surface -0-30 cm- and subsurface -30-60 cm- layers ; and 2. Total contents of some heavy metals in the surface layer -0-30 cm- Trials were carried out on the amelioration experimental field Jelenščak- Kutina, on ameliorated pseudogley-gley soil. Trial variants involved pipe drainage spacing of 15 m, 20 m, 25 m and 30 m. All variants were combined with gravel as contact hydraulic material. Drain pipe characteristics were: length 95 m, diameter 65 mm, average slope 3 promills and average depth 1 m. Drain pipes discharge directly into open canals. The same crop was grown and the same agricultural machinery and herbicides were applied in all variants throughout the research period. Soil samples were taken according to fixed seasonal dynamics and were analyzed by common methods. During the three-year -1996-1998- research into the concentrations -residues- of atrazine and heavy metals in the hydroameliorated pseudogley-gley soil of the central Sava valley, atrazine concentrations -residues- in the surface layer -0-30 cm- were found in traces in some variants in 1996 whereas it was not detected in other variants. The average residue -concentration- of atrazine was 1.5 kg per kg for all variants. Compared to 1996, an increased level -residue- of atrazine was recorded in all variants in 1997. The average atrazine residue amounted to 11.0 kg per kg. The atrazine residue recorded in 1998 was lower than in the preceding year. The average value for all trial variants amounted to 8.0 kg per kg. No atrazine residues were detected in the subsurface layer -30-60 cm- during the research period. An increased atrazine residue -concentration- in soil in the second trial year and its relatively high residue in the third year point to the conclusion that a negligible amount of atrazine gets decomposed and that it partially accumulates or binds to soil clay particles. This calls for caution in atrazine application to hydroameliorated areas of pseudogley-gley soil in the agroecological conditions of the central Sava valley. Maximum levels of heavy metals -Cu, Zn, Cd, Pb and Ni- did not surpass tolerable values, prescribed by the Rule Book on Protection of Agricultural Soils from Pollution by Harmful Substances, -Official Gazette 15-92-. The average three-year maximum values -for all variants- were as follows: Cu 26.7 mg per kg, Zn 89.7 mg per kg, Cd 0.8 mg per kg, Pb 13.8 mg per kg and Ni 37.7 mg per kg. Pursuant to the level of soil pollution by the studied heavy metals, the soil is unburdened by Pb, pollution by Cu, Zn and Cd is increased, while the level of pollution by Ni is high. The raised soil content of Ni is commonly associated with an increased level of organic component, but also with the content of iron and aluminium oxides. The obtained results point to the need of further control of the content and behaviour of particular heavy metals in this soil type and under the prevailing agroecological conditions.

Atrazin im Boden; schwere Metalle im Boden; hydromeliorierter; Pseudogley-Gley

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