Sweet Corn Fertilizer Management In the Mid-Atlantic

Virginia farmers produce over 3,000 commercial acres of fresh market sweet corn (Zea mays) yielding 35 cwt/A and valued in excess of 2.5 million dollars. Fertilizer costs are now a major crop input and farmers are interested in ways to increase their fertilizer use efficiency. Research plots were established at the Virginia Tech Eastern Shore Agricultural Research and Extension Center near Painter, Virginia in Spring 2009 on a Bojac sandy loam (Coarse-loamy, mixed, semiactive, thermic Typic Hapludults). The experiment was arranged as a factorial arrangement of 3 N rates (60, 120, and 180 lbs N/acre) × 3 nitrogen (N) sources [liquid urea-ammonium nitrate (UAN, 30% N), ammonium nitrate (AN, 34% N), and ammonium sulfate nitrate [Sulf-N26, 26% N and 14% sulfur (S)], plus a 0-N control. Two additional treatments were applied and analyzed separately to test for S response. Sulfur as gypsum was applied at Sulf-N26 equivalent rates for 120 lbs N/A (65 lbs S/A) to additional plots fertilized using UAN (UAN + S = UANS) and AN (AN + S = ANS). Yield and ear quality parameters were measured. Sulf-N26 had a quadratic relationship with N rate and yielded highest (14,858 lbs/A) with 117 lbs N/A. Ammonium nitrate had highest yields using 125 lbs N/A while UAN peaked at 110 lbs N/A (13,230 and 13,329 lbs corn/A, respectively). Overall, Sulf-N26 is an acceptable fertilizer source for Mid-Atlantic sweet corn production and may offer yield advantages over traditional fertilizer sources. However, we cannot say conclusively yield advantages were due to S fertilization. More research is necessary to further quantify appropriate N rates for various N sources and to determine S fertilizer needs in the Mid-Atlantic.