• To avoid loss of fall applied nitrogen use a nitrification inhibitor and wait until soil temperature reaches 50⁰F.
• Nitrification process slows below 50⁰F (soil temperature), completely ceasing when soil temperatures approach 32⁰F and below.
• N-Serve™ is a bactericide that kills nitrosomonas bacteria, while Centuro™ is a bacteriostat that inhibits the production of the enzyme ammonia monooxygenase (AMO), required to convert ammonium to nitrate.
• Independent and Koch Agronomic Services research data show both products to work equally well to inhibit nitrification.

Fall is approaching and with it comes anhydrous ammonia application.As soil temperatures drop to 50⁰ F and are trending lower then it is the time for anhydrous ammonia and a nitrification inhibitor to be applied. Two nitrogen stabilizers that will be discussed in this article include N-Serve™ (Corteva) and Centuro™ from Koch Agronomic Services. We will review the process through which each product inhibits nitrification as well as their handling and storage differences.

Nitrification of ammonium based fertilizers is carried out by nitrosomonas bacteria in the soil. At temperatures greater than 50⁰ F in the soil, bacteria actively go about the conversion process. As soil temperatures drop below 50⁰ F, the conversion process begins to slow down completely stopping after the soil temperature drops below 32⁰F. Corteva’s N-Serve™ acts as a bactericide, killing nitrosomonas stopping the conversion process until nitrapyrin the active ingredient degrades.Once N-Serve™ bactericidal properties degrade, soil bacteria populations rebound and conversion of ammonium to nitrate resumes. On the other hand Centuro™ has bacteriostatic properties.It blocks a specific enzyme (AMO) produced by the nitrosomonas bacteria required to oxidize ammonium to nitrate. During this blockage bacteria remain viable. Once Centuro™ breaks down in the soil the enzyme production of AMO by nitrosomonas resumes allowing ammonium to be oxidized to nitrate.Both independent (University of Nebraska, University of Missouri, and the Illinois Fertilizer & Chemical Association) and Koch two-year research data indicate that neither product performs significantly better than the other to inhibit the nitrification process. Broad scale use of both of these products in the next few seasons will verify small scale research data.

Handling & storage properties are different between the two chemistries. Property differences are outlined in the table below using information that can be found on each company’s websites. Nitrapyrin’s carrier is a mix of benzenes, xylene and cumene making the product corrosive to equipment. Centuro’s™ active ingredient pronitridine carrier is water based and non-corrosive making it easier on equipment, and with fewer storage container restrictions. Centuro™ can be stored for two years in bulk, mini-bulk or in anhydrous ammonia without harm to equipment or potential for reduced effectiveness of product. N-Serve cannot be mixed and stored in anhydrous ammonia beyond 3 weeks.

In terms of use rate and cost implications, the rate of Centuro™ is 5 gallons per ton and for this reason cost per acre varies with the anhydrous ammonia rate applied per acre. N-Serve™ is applied at a rate of a quart per acre for field corn production regardless of application rate of nitrogen. These differences in application rate makes it difficult to compare Centuro’s™ cost per acre to N-Serves cost constant rate per acre. For more information on nitrogen stabilizers contact your local FS crop specialist.