njemački

Verschmutzung des Dranwassers auf einem Melioration Pseudogley-Gley Standort

It is known fact that conventional agriculture with its agrotechnical practices –fertilization, protection, etc.- may influence soil and water pollution. For this reason, it is necessary to think and act in terms of sustainable agriculture. However, untill the awareness and material means for extensive use of sustainable agriculture are achieved, potential soil and water pollutants should be controlled and their levels in soil and water monitored in conventional agriculture. The aim of this research was to assess drainage water pollution with nitrate and ammonia forms of nitrogen, some heavy metals and atrazine. Research was carried out for 3 years –1995-1997- on the amelioration trial field Jelenščak near Kutina, on drained pseudogley-gley soil. Variants of drain pipe spacing of 15 m, 20 m, 25 m and 30 m were studied, in combination with contact –hydraulic- material – gravel –diameter 5-25 mm- and without contact material. Drain pipes were 95 m long, of 65 mm diameter, 3 promiles average slope, and 1 m average depth, discharging directly into canals. The same crop was grown in all variants and the same agricultural practices were applied in each trial year. Winter wheat was grown in 1995. A total of 180 kg of nitrogen was added with fertilization. Maize was grown in 1996 and 1997. 145 kg per ha and 175 kg per ha, respectively, of nitrogen were added with fertilization. In 1996, weed control was carried out with liquid herbicide Primextra 500 –20 percent atrazine plus 30 percent metolachlor- at a rate of 6 l per ha. In 1997, weed control involved a combination of liquid herbicide Primextra 500 at 6 l per ha plus Racer 25 FC –fluochloridon- at 1 l per ha. Samples of drainage water were taken according to seasonal dynamics. Analysis of NO_3, NH_4 and heavy metals were performed by standard methods –APHA, 1992-, while gas chromatography was applied for qualitative and quantitative analyses of atrazine. The three-year research results –1995-1997- show that maximum NO_3 concentrations were higher than admissible 50 mg per l in all trial variants while the average value was below it. Maximum concentrations were recorded either in autmn or in spring after fertilization –topdressing- was applied to the crop, which usually coincided with the primary or secondary precipitation maximum. NH_4 values were below 5 mg per l in all variants. In 1995, a total amount of 20.10 kg per ha was, on average, leached from all trial variants, or 11.16 percent of total nitrogen fertilizer applied. In 1996, total leached amiunted to 16.82 kg per ha –11.07 percent- and to 12.58 kg per ha –7.19 percent- in 1997. Maximum concentrations of heavy metals Pb, Zn, Cd and Cu in drainage water did not exceed the maximum admissible concetrations prescribed by the Law on the Quality of Drinking Water in the Republic of Croatia –Official Gazette 46-94 -. Average and maximum drinking water concentrations of atrazine were higher than 100 micrograms per l and lower than 500 micrograms per l in all variants in 1996 and 1997. The obtained three-year results point to the need of more attention being paid to cleanliness of drainage water in conventional agriculture.

Konzentration NO_3; NH_4 schwerer Metalle und Atrazines im Dranwasser; hydromeliorierter Pseudogley-Gley

nije evidentirano