How Would You Manage In-Season Potassium Deficiency In Soybeans?
By Rasel Parvej, David Moseley, Josh Copes, and Syam Dodla
LSU AgCenter
Potassium (K) is the second most yield limiting nutrient in soybean. Even though nitrogen (N) is the most limiting nutrient, soybean plant meets its own N requirement through biological N-fixation. Therefore, soybean is mainly fertilized with K and phosphorus (P) fertilizers in soils that are tested very low to medium K and P levels. Soybean is more responsive to K than P fertilizer and requires a large amount of K to maintain optimum water balance in plants, increase photosynthesis and assimilate translocation from source to sink, reduce transpiration losses of water, and improve uptake of other nutrients. A 55-bushel soybean requires about 160 pounds K2O (potassium oxide) per acre, approximately 2.9 pounds K2O per bushel grain harvested.