Starter fertilizers for corn on soils testing high in phosphorus in the northeastern USA

Starter fertilizers with a high P analysis are commonly used in the northeastern USA for corn (Zea mays L.) production, despite many soils testing above optimum (>50 mg P kg^-1). The objective of this study was to evaluate responses to high P starter fertilizers in a band 5 cm from the row compared to alternatives such us banded higher N or conventional and low-salt in-furrow fertilizers. Two studies were conducted during 2000 through 2003 in Pennsylvania. The first study was a 3-yr on-farm study conducted to evaluate an untreated check, (NH₄)₂SO₄ (AS), and 10-13-8.3 (N-P-K) as starters at 41 locations across Pennsylvania on high P testing soils. Early growth increased by 17% using 10-13-8.3 and 15% using AS compared to the check. Grain yields were 3.3% higher than the check for the AS treatment. Yields from the 10-13-8.3 were not different than the check but averaged 2.0% higher. A second 3-yr study consisted of an untreated check, five banded granular starter fertilizer blends (10-13-8.3, 21-0-0-24, 16-3.5-6.7-16, 16-3.5-6.7, and 16-0-6.7-16) applied at 202 leg ha^-1, and three liquid in-furrow treatments applied at 35 kg ha^-1 (7-9.1-5.8, 7-7.4-2.5 and 7-7.8-7.5). Early growth and grain yield were significantly increased in 1 of 3 yr with some higher N starters. Eliminating starters, using higher N or in-furrow starters on high P soils all appear to be possible management alternatives to high P starters.