Nutrient Deficiency as a Co-factor of Red Clover and Lucerne Decline

Purpose Forage legumes like red clover ( Trifolium praten se L.) and lucerne ( Medicago sativa L.) are an important part of crop rotations in sustainable farming systems. However, the phenomenon of clover or lucerne decline, in which growth and vitality decreases, threatens yield security and additional benefits. Causes of decline are often seen in pathogens, but the occurrence of decline symptoms in confined patches, while neighbouring areas remain healthy, implies additional influences. This study investigates whether nutrient deficiency is a factor of legume decline. Methods Over a period of three years, we conducted a nationwide survey in which reported cases of red clover or lucerne decline were investigated, comparing soil nutrient profiles of decline patches with nearby healthy areas by Wilcoxon test for paired samples. Classification tree and correlation analysis were used to resolve variable dependencies. Results Contents of boron (for deficient sites), sulphur and iron (for red clover sites) were significantly lower on decline patches compared to healthy areas, indicating deficiencies as possible causes of decline symptoms. In addition, soil copper, potassium, phosphorus and zinc contents as well as soil texture and soil organic matter contents are suspected of influencing the occurrence of red clover or lucerne decline. Conclusions Deficiencies as potential causal agents of legume decline can occur for all nutrients but are more likely to stay unnoticed for micronutrients due to less frequent testing.