Effect of Environmentally Smart Nitrogen (ESN®) On Corn Yields in Eastern Ontario.

Nitrogen (N) availability to crop and losses to environment have always been an issue when deciding when, how and how much N should be applied. Slow-release “Environmentally Smart Nitrogen (ESN^®)” was developed in an effort to supply N to the crop at the right time while minimizing the number of passes on the field. ESN consists of a urea granule provided with a semi-permeable polymer coating that allows water to enter the granule and dissolve the nitrogen inside based on temperature and moisture. The objective of this project was to evaluate the advantages of ESN versus straight urea on two different sites with contrasting soil texture. An experiment was carried out in 2011 and 2012 on two sites in eastern Ontario; Winchester (clay-loam soil) and Kemptville (sandy loam soil). A total of ten treatments were applied using three N rates (50, 100 and 150 kg N ha^-1) times 3 different combinations for each rate (100% urea, 75/25 urea/ESN, and 60/40 urea/ESN), in addition to a non-fertilized control.

In 3 site/years, the effect of N application on yield was not significant. In Winchester 2012, the effect of the treatment was significant mainly due to the rate level (higher yields with higher total N rates), but ESN was rather depressing to yields. However, in Winchester 2011, at a rate of 150 kg/ha, a urea-ESN blend had a yield advantage of 11-12% (17-19 bu ac^-1) compared to straight urea. Corn yield did not benefit from the highest urea application (150 kg ha^-1) compared to 100 kg/ha. On the other hand, 60/40 blend of urea/ESN seemed to depress yields compared to straight urea. Leaf chlorophyll content was highest with 75/25 blends. Grain moisture content, test weight and thousand-kernel weight were little affected by the N treatments.