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The objective was to estimate the potential risk of N leaching into the groundwater under various types of agriculture by using lysimeter experiments on the nitrogen(N)‐cycle of various soil types. Results were obtained with 12 weighable, monolithic lysimeters with a surface area of 1 m2, a total depth of 3 m, and free drainage. Mean annual N‐leaching losses of 5 to 44 kg ha—1 and nitrate concentrations of the seepage water (leachate) between 80 and 200 mg l—1 were measured during the period of intensive agricultural use. On fallow land with a well‐established grass vegetation, some nitrate was removed by the plants. As a result, the nitrate concentrations in the leachate were reduced significantly. Ecological farming measures generally reduced N leaching losses and kept the N‐concentration in the leachate below the German threshold value for drinking water with 50 mg l—1 nitrate. However, ploughing in of clover or leguminous vegetation and the application of farmyard manure in autumn caused the nitrate concentration in the leachate to rise significantly above the mentioned threshold value.<?show $6#> 相似文献
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Water and Solute Balances in Recultivated Lignite Mining Dump Soils-Field Data and Lysimeter Experiments 总被引：1，自引：0，他引：1
Knappe S. Haferkorn U. Mattusch J. Meißner R. Rupp H. Wennrich R. 《Water, air, and soil pollution》2004,157(1-4):85-105
Specific problems of water and solute balancing in the central German post-lignite-mining district are caused by the almost unknown interactions between surface water, seepage and groundwater in the unsaturated zone of mining dumps. This paper presents the findings of studies using lysimeter and seepage groundwater measuring systems designed to investigate the water balance and the migration of inorganic components in the vadose zone of recultivated dumps. Despite the heterogeneous tertiary layers of the three lysimeter monoliths studied, the quantity of seepage occurring at a depth of 3 m as well as the evapotranspiration and the soil water regime were almost the same in the 4 years of the investigation. The high variability of the ion balances in seepage reflects inhomogeneities in tertiary dump material and can be explained by substrate properties interacting with the soil's pH. Very high seepage conductivities are caused by coal containing high levels of pyrite with a low pH and high acid potential. These conductivities are caused by comparatively high concentrations of ions of sulphate, iron, aluminium, calcium, magnesium and heavy metals. The results confirm the impact of ventilated and pyrite-containing dump substrates for groundwater quality. 相似文献
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The goal of these studies was to evaluate lysimeter experiments performed over a number of years on the nitrogen cycle of different soil types to estimate the potential hazard of various types of farming usage resulting from N-leaching losses into the groundwater. The studies were carried out in monolithic lysimeters measuring 1m2 with a depth of 3m located in Brandis (near Leipzig, Saxony, Germany). The soils were four pedohydrotopes (Top a-d) characterised by increasing depth, usable field capacity (nFK) and sorption capacity. The average values calculated for the experiments lasting 21 years were as follows for the extreme pedohydrotopes a and d respectively: annual nitrogen losses - 85 and 185kg/ha; annual nitrogen leaching -51 and 5kg/ha; and leachate nitrate levels - 100 and 39mg/l. Viewed on a year-by-year basis, effects due to weathering and soil type outweighed the usage-related leaching risk. Organic farming usually reduces N leaching and the leachate N level below the recommended limits. However, ploughing in clover (usually carried out in autumn to improve the supply of nutrients in biologically dynamic organic agriculture) and also spreading stable manure combined with winter black fallow raised the level of nitrate in leachate above the maxima. Hence N fertilisation as prescribed by the computer program BEFU within environmentally sustainable land use does not appear to be sufficient to significantly reduce N leaching. 相似文献
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