Nitrogen and phosphorus fertilization for efficient corn production in Virginia

Traditional com fertilization methods of broadcasting N fertilizer, and applying P fertilizer to soils testing high to very high in plant-available P, can be inefficent. Experiments were conducted at several locations in Virginia to evaluate if band applications of N fertilizer are more efficient than surface broadcast applications, to determine optimum starter-band and sidedress N rates for com grown in Virginia, to evaluate possible indicators of optimum starter-band and sidedress N rates, and to determine if there is any response to P fertilizer application to com grown on soils testing high to very high in plant-available P. Starter-band N rates of 11, 34, 56, and 78 kg ha⁻¹, and a treatment of 67 kg ha⁻¹ broadcast plus 11 kg ha⁻¹ in a starter-band, were applied in combination with sidedress-N rates of 0, 67, 134, and 202 kg ha⁻¹. In the phosphorus experiment, starter-band rates of 0, 22, 45, and 67 kg P₂O₅ ha⁻¹ were applied. Band application of N increased com plant tissue N content at most locations compared to broadcast application. Fifty-six kg ha⁻¹ was determined to be an economically viable starter-band N rate for com grown in Virginia. Optimum sidedress N rates were determined to be site- and season-dependent and no indicators of optimum starter-band N rates or sidedress N rates were observed. On soils testing high to very high in plant-available P, grain yield did not respond to additions of P fertilizer.