WHAT IS A NITROGEN STABILIZER?
Nitrogen fertilizer is one of the largest input costs for growers today. A nitrogen stabilizer helps protect your investment, by keeping the nitrogen you apply in a stable and usable form until your crop needs it most.
WHAT HAPPENS TO APPLIED NITROGEN?
After application, nitrogen sources in the ammonium form (NH4+) rapidly convert to the nitrate form (NO3-) via a process called nitrification. Temperature-sensitive soil bacteria called Nitrosomonas converts ammonium (NH4+) to the nitrite form (NO2-). Another bacteria, Nitrobacter, then converts nitrites (NO2-) to the nitrate form (NO3-). These soil microbes become more active when soil temperatures reach 10℃ and higher causing a faster rate of conversion. Soil has a negative charge, and as such, does not form strong bonds with negatively charged nitrates.
Although nitrates are taken up by the plant, they are also prone to leaching from the root zone and denitrification. This means they may not be available for the plant when it needs it most.
HOW DO CROPS USE NITROGEN?
Crops use nitrogen in two forms: ammonium NH4+ and nitrate NO3-
- The ammonium form (NH4+), is more efficiently used by plants and more stable in soil.
- The nitrate form (NO3-), is less efficiently used and more likely to be lost to leaching and denitrification.
Leaching is the loss of nitrates from the soil below the root zone due to rain and irrigation. Since soil and organic matter also are negatively charged, the nitrates are repelled and can be easily washed away, especially in coarse, sandy soils.
Denitrification refers to the loss of nitrogen when soil microbes convert nitrates to gaseous forms that can escape into the atmosphere as a greenhouse gas. Denitrification affects only nitrates, not ammonium.
ARE THERE DIFFERENT TYPES OF NITROGEN STABILIZERS?
There are three different types of nitrogen stabilizers
- Slow release
- Urease inhibitors
- Nitrification inhibitors
Slow release is urea coated with synthetic polymer. Water diffuses through the coating, dissolves the urea pellet and liquid N diffuses out. It is ideal for seed placed nitrogen as it is quite safe next to the seed. The downside is that the nitrogen is only available once the breakdown of the coating has taken place. ESN® is an example of slow release.
Urease inhibitors inhibit the urease enzyme which catalyzes the hydrolysis of urea left on the soil surface. Any small amount of soil moisture causes unprotected urea to hydrolyze and convert to ammonium and carbon dioxide which may then be lost through volatilization. Urease inhibitors only provide benefit when the urea is on the soil surface. If you seed place your urea, then urease inhibitors offer little benefit. An example of a urease inhibitor is Agrotain®.
Nitrification inhibitors inhibit the Nitrosomonas bacteria, which initiate the conversion from ammonium nitrogen (NH4+) to nitrate nitrogen (NO3-). They slow the conversion of ammonium to nitrate by inhibiting the first stage of nitrification to store usable nitrogen at the root zone. N-Serve and eNtrench are examples of nitrification inhibitors.
WHAT DOES NITRAPYRIN DO?
Nitrapyrin is the active ingredient in N-Serve™ and eNtrench™. It slows the activity of the Nitrosomonas bacteria, which converts ammonium to nitrites, for up to 10 weeks in warm soils (>10℃). This reduces the risk of loss due to leaching and denitrification allowing the nitrogen to be available during peak periods of need by the crop.
Nitrapyrin is a nitrification inhibitor which keeps applied nitrogen in a stable form in the root zone longer. Proven effective in the U.S. for over 35 years, Nitrapyrin is now available in Canada.
SOIL TEST TRIALS
2014 Dow AgroSciences soil test trials.
Nitrogen applied in early October 2013. Soil test completed before seeding in early May 2014.4
18% more plant available nitrogen in the + ammonium form when using Nitrapyrin.
1 Fertilizer cost in Western Canada is 18% lower in the fall, based on a15-year average.
2 Based on Dow AgroSciences U.S. research trials.
3 Source: J.D. Wolt. 2004. A meta-evaluation of nitrapyrin agronomic and environmental effectiveness with emphasis on corn production in the Midwestern USA. Nutrient Cycling in AgroEcosystems. Vol. 69. Issue 1, pp 23-41.
4 Based on two plot trials.