Evaluation of Ammonium Sulfate Nitrate in Virginia Sweet Corn Production


08 Apr 2013

2012 Annual Interpretive Summary

Virginia farmers grow over 3,000 acres of fresh market sweet corn. They are interested in exploring sources and rates to improve N use efficiency. This trial compared three N sources (urea-ammonium nitrate, ammonium nitrate, and ammonium sulfate-nitrate) at three rates. The first two N sources were compared with and without S, applied as gypsum, at a rate designed to supply the equivalent amount of S provided by ammonium sulfate-nitrate (65 lb/A).

Averaged over two seasons (2009 and 2010), the three N sources increased marketable yields by 30 to 65% using optimum N rates ranging from 110 to 170 lb/A. Agronomic efficiency at optimum rates ranged from 26 to 45 lb of marketable yield increase per lb of N applied. Sulfur added as gypsum did not increase yields, and sources did not show consistent differences across the two seasons. In 2011, excessive heat during silking caused limited kernel set and thus marketable yields were zero. Application of N increased total yield, but the small differences among sources are unlikely to mean anything for years in which a marketable yield is achieved. In 2012, application of N increased total and marketable yields, regardless of N source. Application of S did not significantly increase yields, but certainly did not reduce them either.

In conclusion, ammonium nitrate, urea-ammonium nitrate, and ammonium sulfate nitrate were found to be acceptable N fertilizer sources for sweet corn on sandy loam soils. In some years, plants may benefit from S additions. These findings support N management decisions that optimize food yields while minimizing risk of water contamination by N on the sandy loam soils of the Chesapeake Bay watershed. VA-23F