Interest in potassium (K) fertility in soybean has increased recently. The primary source of potassium fertilizer is KCl which contains 50% chloride (Cl) by weight. Soybean yield decreases have been found during recent years and decreased grain protein and increased oil have occurred for soybean within K trials conducted across Minnesota. The goal of this work is to determine whether Cl applied to soybean may negatively impact soybean grain yield and quality and whether Minnesota soybean farmers need to avoid application of KCl directly ahead of the soybean crop or apply a different source of K fertilizer. Past research has shown yield decreases in single year K fertility trials but long-term...