Alfalfa doesn’t need fall potassium fertilizer application to aid winter hardiness in Minnesota, research shows
Image credit: Paul McDivitt/University of Minnesota Extension By: Paul McDivitt, Extension communications specialist Alfalfa growers in Minnesota typically apply potassium (K) fertilizer twice each year: once during the growing season and once in the fall to promote overwintering. However, recent research by the University of Minnesota indicates that a second, fall K application has no effect on alfalfa’s winter hardiness. The data show no difference between spring alfalfa stands that received a fall K application and those that did not. This contrasts with older information and common knowledge prevalent today. The researchers attribute their findings to two likely factors: Modern alfalfa varieties have been bred for greater winter hardiness, so they don’t need as much K for overwintering as past varieties. Previous research showing a benefit from fall K application was likely done on soils with much lower K levels than we have today. They recommend testing soils and ap