The differences between NBPT, DCD and DMPP
Understanding and preventing nitrogen loss
Using nitrogen stabilizers to halt the processes responsible for nitrogen loss in urea/UAN fertilizer provides substantial agronomic and economic benefits – ensuring you get the most bang for your buck. Today, we look at how and when to use NBPT, DCD and DMPP, the three most common nitrogen stabilizers for urea/UAN fertilizer.
NBPT protects against loss in the volatilization stage of the nitrogen cycle. DCD and DMPP (a next generation product with many advantages) protect against loss in the nitrification stage.
* For a more detailed overview of volatilization, denitrification and the nitrogen cycle, read the Taurus Two Minute Drill.
NBPT Stabilizers – Preventing volatilization by slowing nitrogen conversion
Common name: NBPT
Chemistry: N-(n-butyl) thiophosphoric triamide
Category: Urease Enzyme Inhibitor
Growers are often stunned to learn they can lose up to 50% of the Nitrogen supply in their urea/UAN fertilizer due to Ammonia volatilization (gassing off).
Fortunately, NBPT stabilizers can be blended with urea/UAN to prevent nitrogen loss due to volatilization by up to 98% (results are dependent on a number of factors, including soil conditions, temperature and moisture).
Why does nitrogen loss happen after a urea/UAN application?
Volatilization occurs when urease enzyme in the soil converts urea into ammonia gas (NH3) before it can acquire the hydrogen molecules necessary to transform into the stable, plant-available form: Ammonium (NH4).
This conversion commonly takes place quite rapidly: within 2 to 10 days of application.
Soil pH impacts the availability of hydrogen. It is most abundant in low pH (acidic soils), becoming less abundant the higher the pH. So, while highly basic soils are most prone, you may be surprised to learn that even in neutral soils (6.5 to 7.5 pH) nitrogen losses can range between 22% to 40% within 10 days. Even in acidic soils, the loss is close to 10%. So, volatilization is a serious concern for anyone applying urea/UAN 
Moisture, particularly rainfall, is a key source of hydrogen – and is seen as necessary when applying urea/UAN. According to research, a minimum one-half inch of precipitation is required from a single weather event (or irrigation) to stabilize urea/UAN deep enough into the soil to protect it from volatilization.
How does NBPT work?
NBPT minimizes urease enzyme activity, which slows the conversion of urea to ammonia gas. It can extend the conversion period by as much as 14-28 days (vs. 2-7 days) depending on conditions.
This buys time so the soil can buffer more hydrogen – resulting in the successful conversion into the stable, usable ammonium form.
DCD and DMPP Inhibitors – protecting ammonium from conversion by bacteria
Nitrogen loss can also take place in the denitrification stage of the nitrogen cycle. This process involves bacteria converting ammonium to nitrite and then nitrate. Nitrogen loss can then occur through denitrification or leaching.
While nitrate is plant-available, it is not stable. For this reason, ammonium is the preferred state of nitrogen in the soil.
How do DCD and DMPP work?
Both of these nitrification inhibitors are bactericides that are designed to shut down the activity of the two bacteria responsible for the conversion of ammonium to nitrite and then nitrate: NitroSomonas and NitroBacter bacteria.
DCD – Pioneering chemistry for preventing Ammonium conversion
Common name: DCD
Category: Nitrification Inhibitor
DCD is one of the original nitrification inhibitors, formulated with technology developed in the 1970s.
DCD remains active for 25 to 50 days. It is highly mobile in the soil – and can leach. Bioaccumulation in plants and animals is a possibility with DCD, so it is important to carefully follow all label instructions to ensure the safe application of this product.
DCD is sold in a powder formulation. It must be applied at relatively high concentrations.
DMPP – The evolution of ammonium protection.
Common name: DMPP
Chemistry: 3,4-Dimethylpyrazole phosphate
Category: Nitrification Inhibitor
DMPP is relatively new to Canada, but it is a well-established chemistry that has been widely used in Europe for several years. It was developed as the next-generation nitrification inhibitor. DMPP has several advantages :
- Safety: DMPP does not accumulate in organisms. It is not mobile in the soil and remains where it was applied.
- Lower rate: DMPP is applied at significantly lower concentrations
- Extended soil activity: DMPP is active in the soil from 20 to 70 days.
- Easier handling: The lower rate greatly reduces handling issues. While the majority of DMPP is a powder, there is less product to handle. The first liquid version has just been released in Canada (packaged with NBPT as a dual nitrogen stabilizer).
- Performance: DMPP is shown to be more effective in preventing the conversion of ammonium to nitrate in high N level vegetable soil, at a much lower application rate.
Do you require NBPT or DMPP/ DCD to protect your nitrogen investment?
As you can see, there are distinct differences between NBPT, DCD and DMPP. However, the goal is the same: to ensure your plants reap the full benefit from your nitrogen application – while protecting your urea/UAN investment.
Key situations where a nitrogen stabilizer is recommended:
|Urease Inhibitor (NBPT)||Nitrification Inhibitors (DCD, DMPP)|
|-Neutral and high pH soils (lower Hydrogen content)||-Highly saturated/waterlogged soils|
|-Fields with high thatch content (20 to 30x increased presence of urease enzyme) – no-till or minimum till||-Course textured soils that are prone to leaching|
|-Soils with low cation exchange capacity (CEC)/ Poorly buffered soils (low organic matter, low bicarbonate content, high sand content) – course soils||-Heavy textured soils that are low in O2 (compacted soils)|
|-Applications where conversion of Ammonium to Nitrite can still take place. (temperatures of +4°C or warmer)|
- Overdahl et al., 1960. Soil Sci. Soc. Am. Proc. 24: 87-90.
- Factors Affecting Nitrogen Fertilizer Volatilization- Montana State University Extension paper EB0208.
- Effects of 3,4-dimethylpyrazole phosphate and dicyandiamideon nitrous oxide emission in a greenhouse vegetable soil. Kou, Wei, Chen, Wang and Xu. Plant Soil Environ., Vol. 61, No. 1, 2015.