Nährstoffversorgung von Ackerbohnen im Ökologischen Landbau

Inadequate nutrient supply frequently limits biological nitrogen fixation (BNF), plant growth and grain yield of legumes. Under no-till conditions, root growth may be restrained and therefore reduce nutrient uptake. Our studies were carried out to assess the nutrient status of Vicia faba L. (particularly at the onset of bloom) in Germany by using newly created DRIS (Diagnosis and Recommendation Integrated System) norm values, Critical Nutrient Levels (CNL), and the optimum nutrient range. In a field experiment in 2010 at 4 sites (Klein-Altendorf, Wiesengut & 2 organic farms) the applied fertilizers were fermentation residues, compost, pomace, meat-bone-meal, rock-phosphate, sodium-molybdate, potassium sulphate, and borax. Nutrient elements measured in leaf samples were: C, N, S, K, Ca, P, Mg, Fe, Mn, Zn, Cu, B and Mo. As S was detected to be deficient, K2SO4 (35 kg S/ha) had a significantly positive effect on plant growth, yield and symbiosis