INFLUENCE OF MINERAL FERTILIZERS AND DIFFERENT SOIL TYPES ON NUTRIENTLEACHING - RESULTS OF LYSIMETER STUDIES IN EAST-GERMANY

A lysimeter experiment on mineral fertilizer use and soil type was beg un in 1985 to study the interrelationships between the level of minera l fertilization and the leaching of nutrients. Increased application o f mineral fertilizers brought about not only a significant reduction i n effluence build-up, but also a significant increase in yield. The lo west levels of nitrogen leaching were found in clay-sand soil in use a s grassland, and the highest in sandy soil used as arable land. Unexpe ctedly, the study was unable to prove statistically that a reduction i n N, P and K leaching follows automatically from a reduction in minera l fertilization. Hence, suboptimal fertilization cannot be the only co rrective measure if a noticeable or marked reduction in the adverse im pact on water quality due to nutrient leaching is to be achieved. Inte rim plantings should be integrated in crop rotations. Agricultural cro ps must be site-adapted and suited to the fertilization regime.