Methoden zur Ermittlung von Grenzwerten der Phosphor-, Kalium- und Magnesium-Gehalte in Ackerböden

Assessment of critical values of phosphorus, potassium, and magnesium contents in arable soils Long-term fertilizer field experiments were carried out in order to calibrate soil test values for P, K, and Mg. In several years treatments gradually resulted in differences of soil nutrient contents. This made it possible to investigate the effect of fertilizer application on the relation between yield of plants and soil nutrient content. Methods were suggested to evaluate these relationships and to calculate critical soil nutrient contents. Emphasis was mainly directed towards the definition of level 3 of nutrient supply because it represents the aim of economic fertilizer application.