Early Season Nutrient Uptake From Combinations of Nitrogen, Phosphorus, and Potassium Applied in Starter Fertilizer On Two Corn Hybrids.

Minnesota corn (Zea mays L.) farmers utilize starter fertilizers to increase early growth and nutrient uptake with the hope of ultimately increasing yield.  Commercial blends of 10-15-0 (N-P-K) formulations have been used for many years because of widespread availability.  Many other liquid fertilizer formulations with K are sold, but the benefits from K in starter are not clearly understood.  This study assessed the impacts of N, P, K applied alone or in combination as a starter fertilizer on early corn growth, plant N, P, and K concentration, and nutrient uptake.  Trials were arranged in a split plot design where main plots consisted of a control and five liquid starter treatments (N only, N+P, N+P+K, N+K, and K only) and two near isoline corn hybrids (DK 50-44 VT3 and DK 50-48 RR YGCB) comprised the sub plots.  The same hybrids were used at four locations which tested medium or higher in soil P (>10 mg kg^-1) and K (> 80 mg kg^-1).  Starter rates applied 10 kg N, 10 kg P, or 18 kg K ha^-1.  Starter P increased early plant growth and adding K increased growth more than P alone across locations.  On average, hybrids did not differ in plant growth.  Corn N, P, and K concentration was seldom influenced by starter treatments.    Across locations, N+P+K starter treatments increased uptake more than other nutrient combinations.  Starter N+P increased uptake of all nutrients greater than most other treatments (except N+P+K), even K uptake although none was applied.  Increased K uptake was due to a significant relationship between growth and uptake.  Data from the first year of this study confirms that P is important for early plant growth and nutrient uptake, but in certain circumstances the addition of K with P may be beneficial to further increase early plant growth.