For whatever reason, there are a few agronomy topics that never seem to fully get sorted out — seeding by thousand kernel weight, the right time to spray for wheat midge and what the difference between ESN and Agrotain is, for example. Let’s tackle the last on the list. Here’s a quick reminder of what the products are and how to best use them.
First, the two are similar in that they both are used to minimize nitrogen losses and are both applied to N fertilizer. That’s where the similarities end, however. ESN Smart Nitrogen, an Agrium Advanced Technologies product, is a polymer coating added to urea. It turns regular N fertilizer into slow release N, as N is released as the polymer coating breaks down. ESN is a great fit for winter wheat production, as you can treat a portion (or all) of the N you put down in the fall, where it will remain safely snug in the polymer until the spring when the crop needs it. For spring seeded crops, using ESN means that a portion of the N will be released later in the season, closer to when the crop actually needs it. Losses via leaching, volatilization or denitrificaiton of ESN-treated N are minimized or eliminated until then.
Agrotain is a urease inhibitor added either to urea or to UAN. Urease is a naturally occurring soil enzyme that converts urea to ammonia. Ammonia can then be lost to the air (volatilization). Agrotain inhibits this process, a significant factor of N loss immediately after application, buying time before rainfall or irrigation moves the N into the soil and natural processes convert the urea/UAN into plant available forms of N. There is also a second product, Agrotain Plus, that contains a second product, one that protects against denitrification and leaching losses.
Both ESN and Agrotain come at a cost per pound of fertilizer, but both can and do protect against costly N losses. Which you use when depends on your timing, management style or plan (fall vs. spring seeding or fertilizer application) and the weather.