Corn Response to Environmentally Smart Nitrogen in the Mid South USA.

Corn (Zea mays) hectares in the Mississippi Delta have increased by 50% since the late 1990’s. The majority of the increase in acreage is cultivated in a furrow-irrigated environment.  Nitrogen loss in furrow-irrigated corn production can be substantial if N applications are mistimed or mismanaged.  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 and 2012 at the Delta Research and Extension Center near Stoneville, MS 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.  Incorporation events were completed with a middle-buster/furrow cleaner implement.  Grain yield was measured at maturity by harvesting the middle two rows of each corn plot with a small plot combine.  Yields were adjusted to a uniform moisture content of 12.5% for statistical analysis.  For 2011, corn grain yields for all treatments ranged from 7,651 (UTC) to 12,544 (3/4ESN-180-V4) kg ha^-1.  Corn grain yields were statistically similar and followed the numerical order (greatest yielding to lowest yielding) for the 3/4ESN-202-V4, Urea-269-AP, 1/4ESN-202-AP, Urea-202-V4, 1/2ESN-269-V4, 1/4ESN-202-V4, Urea-202-AP, and ESN-269-AP treatments.  ESN applied alone or with a urea blend appeared in 5 of the 8 top yielding treatments.  Four of the eight top yielding treatments occurred when N was applied at the V4 growth 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.