New stabilizer technology expands nitrogen protection

Since the first nitrification inhibitors were introduced in the 1970s to prevent below-
ground losses of ammonia and urea-based fertilizers, these products have shown their value by dramatically increasing nitrogen use efficiency. More recently, the release of Centuro nitrogen stabilizer has provided improved handling characteristics without sacrificing effectiveness.

The impact of nitrification inhibitors has been immense. Countless tons of N have been saved for crop use rather than lost to the atmosphere or our waterways, protecting farmer yields and profits. The ability to reliably apply nitrogen fertilizers over a larger window has also enabled operators to get more accomplished.

While ammoniacal N sources of anhydrous and urea are commonly protected from leaching and denitrification, a significant portion of the nitrogen applied to many fields today remains unprotected. Nitrogen contained in common phosphorus and sulfur fertilizers such as diammonium phosphate (DAP), monoammonium phosphate (MAP) and ammonium sulfate is often overlooked.

Recommendations for DAP (18-46-0), MAP (11-52-0), or Croplex (12-40-0-10S-1Zn-0.3B), are typically based on the P needs for the crop. Similarly, when applying ammonium sulfate (21-0-0-24S), rates are based on the sulfur need. It’s important to consider that these products also contribute meaningful amounts of nitrogen to the fertility program. Depending on when we applied them, we either consider this portion of N left unstabilized or we hope it is close enough to crop uptake that we don’t lose it.

The nitrogen contribution from these products is far from insignificant. For example, a 200-bushel corn crop will remove 90 pounds of phosphorus and call for up to 20 pounds of sulfur depending on soil organic matter. If DAP is your P source and AMS your S source in this scenario, 50 pounds of N per acre is applied to your field from these fertilizers. This could be as high as 25% of your N needs for that crop—all unprotected from below-ground losses such as denitrification and leaching.

Pasture applications have an even higher proportion of unprotected nitrogen. If an application of 60-40-40-10S fertilizer was made to your pasture using SuperU, DAP and AMS, more than 40% of your N would be unprotected from below-ground losses.

Centuro will be available this coming season in new formulations, each of which will contain the same nitrification inhibitor, Pronitridine, that has previously been used to protect anhydrous ammonia. Now, Centuro Upro will protect dry ammoniacal sources of N as well. This means the DAP, MAP, Croplex and AMS in your dry fertilizer blends can be treated and protected. This is true for pre-emergent applications in row crops and eventually over-the-top applications in pastures, pending label update approvals.

Much still needs to be answered with these products. When will label updates come? How do we efficiently treat these products in a multi-product fertilizer blend? How long will these sources be protected when impregnated with Centuro? Should our N rates of these products be adjusted?

What we do know is that producers and the environment benefit when we prevent losses of nitrogen to the atmosphere, groundwater or surface water. Crop yields increase when nitrogen is sufficient. Profitability increases when nitrogen use efficiency increases. Nitrogen stabilizers are not the only solution, but producers should be excited about the ability to protect additional sources of nitrogen they are already applying to their fields. 

For more articles from the August/September Today's Farmer Magazine, CLICK HERE.