Long-term Lysimeter Experiments - Findings from Brandis Lysimeter Station 2nd Communication

Abstract

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.

Keywords:

• Lysimeter Studies
• Land Use
• Pedohydrotopes
• Leachate
• Leaching Risk
• Nitrogen Leaching
• Nitrogen Levels