Corn Response to Traditional Nitrogen Sources and Ammonium Sulfate Byproduct.

Nitrogen (N) applications for corn (Zea mays L.) constitute a substantial cost of production and an important one, as corn is very responsive to N. The objective of this study was to evaluate corn grain response to different sources of N [specifically compare traditional sources to a byproduct from Archer Daniels Midland (ADM) operations], timings of application, and rate. A 3-growing seasons (2012- 2014) field experiments was conducted at the Crop Science Research and Education Center near Urbana, Illinois. Nitrogen was applied pre-plant as anhydrous ammonia (AA) (82-0-0), dry ammonium sulfate (AMS) (21-0-0-24S), and ADM’s ammonium sulfate product (ADM-AMS) (5-0-0-3S) at 0, 90, 135, 180 and 225 kg N ha^-1. Also, urea-ammonium nitrate plus sulfur (UAN+S) at 180 kg N ha^-1 was applied as pre-plant and as a split application with 45 kg N ha^-1 pre-plant and 135 kg N ha^-1 at sidedress (V6). Canopy color was measured with SPAD at V6 and V10. At V6, 60 cm-depth soil ammonium and nitrate content were determined. Total above-ground tissue N content was measured at physiological maturity (R6). At harvest, grain yield and grain N removal were determined. Only 2014 showed a significant difference due to N rate and N source. Anhydrous ammonia had significant greater corn yield than AMS and ADM-AMS product, and AMS in turn produced greater yield than ADM-AMS product. The effect of the N source at a fixed N rate (180 kg ha^-1) on corn grain yield was also significant in 2014, where AA had greater corn yields than the other sources. Dry ammonium sulfate had similar grain yield than ADM-AMS, but greater than UAN+S. Splitting the UAN application by adding a portion of the N at sidedress did not increase yield. However, ADM-AMS may be an acceptable N source, agronomically similar to AMS, under most conditions.