Evaluation of starter fertilizers for corn on soils testing high for phosphorus

Many soils are testing in the above optimum range for phosphorus (P) in our region. The use of traditional starter fertilizers for com (Zea mays L.) that supply 20-36 kg P ha^-1 on these soils may not desirable. The objective of this study was to evaluate the response of com to starter fertilizers on typical high P soils and to investigate the need for nitrogen (N), P, potassium (K), or sulfur (S) as a component of starter fertilizers. A starter fertilizer evaluation study was conducted at four sites to evaluate the effects of six materials in notill high P soils. The liquid starter fertilizers were formulated using UAN (Urea-Ammonium nitrate), APP (Ammonium Polyphosphate), AS (Ammonium Sulfate), and KCl (liquid KCl). Starter treatments (kg ha^-1 N-P₂O₅-K₂O-S) consisted of none, 56-0-0 (UAN), 56-34-0 (UAN + APP), 34-34-0 (UAN + APP), 34-34-0-11S(UAN + APP + AS), 10-34-0 (APP), and 11-34-11 (APP + KCl) kg ha^-1N-P₂O₅-K₂O-S. In the starter fertilizer evaluation study, responses to starter were variable. Generally there was little benefit from the addition of P to the starter, but there were occasional benefits in early growth and yield from the addition of K, AS or N. Yields from the AS treatment were similar or superior to the conventional starter treatment, suggesting that AS may have a role as a low P starter fertilizer material on these soils.