Crop Response to Environmentally Smart Nitrogen in the Mid South.

Corn (Zea mays L.) hectares in the Mississippi Delta have rapidly increased since the late 1990’s. The majority of the hectares are cultivated in a furrow-irrigated environment.    Controlled release N sources such as Environmentally Smart Nitrogen (ESN) could potentially offer alternative N management strategies for Mid-South corn producers.  Research was established during 2011, 2012, and 2013 at the Delta Research and Extension Center to evaluate corn response to alternative fertilization strategies. Each trial included five nitrogen source treatments (urea, ESN, and 3 ESN:urea blends that contained either 25, 50, or 75 % of the total N as ESN), two application strategies (preplant (AP), and sidedress (V4)) and two total N rates (202 and 269 kg N ha^-1). Two unfertilized controls (UTC) were included in each replication.  The Nitrogen rate × application time interaction significantly influenced corn grain yield at the commerce SC site during 2012.  Within a nitrogen rate, ESN produced numerically greater corn and lower corn grain yields than corn receiving urea for 202 and 269 kg N ha^-1, respectively.  At the Commerce VFSL site, the nitrogen source × application time interaction was significant.  At planting N applications resulted in ESN producing numerically greatest grain yield that was similar to 25 and 50% ESN blends applied at planting and urea and 50 and 75% ESN blends applied at the V4-V5 growth stage.  In general, across siteyears, ESN alone or blended with urea was numerically superior to urea when N applications were made at planting, in contrast, urea tended to produce numerically greater yields compared to ESN or ESN blends when applied at V4-V5 stage.  Environmentally Smart Nitrogen shows promise as an alternative N management tool, however additional research is needed to determine if ESN or ESN:urea blends are suitable N management strategies for Mid-South corn production.