Those who apply nitrogen fertilizer in the fall generally understand that the nitrification process (a.k.a. the process that contributes to nitrogen loss), is chemically halted when the weather gets cold enough and then begins again as temperatures rise.
However, gaining a deeper knowledge of what happens to fall-applied nitrogen over the winter and into spring can make you better prepared to make the best nitrogen management decisions year-round.
With that in mind, here are a few key takeaways to understand about fall-applied nitrogen as it hibernates over the winter:
- 50 degrees F is a notable temperature benchmark
- The nitrification process is put in motion by a bacteria called Nitrosomonas. It causes the conversion of nitrogen to a nitrate form that can be easily lost. Nitrosomonas bacteria is very active when it is warm, it decreases activity significantly at 50 degrees F and nearly halts under 40 degrees F.
- For fall nitrogen application, temperatures can hover anywhere above, at, or below this Nitrosomonas activity threshold. Ideal application occurs at 50 degrees F and below to minimize the amount of potential nitrogen lost.
- Moisture + warmth = more loss potential
- Warm weather makes Nitrosomonas more active in converting nitrogen to a form vulnerable to loss, but moisture from rain or snowmelt occurring at the same time leads to a higher potential for that nitrogen to be lost via leaching.
- Beware of the transitional weather danger zone
- Fall-applied nitrogen must endure two transitional weather periods, which nitrogen is particularly vulnerable to loss given the points above.
- We know that spring can be unstable and unpredictable, often with large shifts in temperatures and rain amounts.
- Recent years also show us that fall can be equally unpredictable. Unexpected heavy rain, extended periods of warm weather and delayed harvest can impact when (and if) fall nitrogen can be applied and especially impact how vulnerable it is to loss — well before crops are ready to use it.
Fall-applied nitrogen is a fantastic way to prepare fields for the coming year and can help alleviate some of the workload in spring. But, science shows us that nitrogen is vulnerable to loss from the moment it is applied. To get the benefits of fall-applied nitrogen but ensure it’s there for your crops come spring, it’s best to protect it with a proven nitrogen stabilizer, like N-Serve®.
N-Serve protects nitrogen from leaching and denitrification, so it’s guarded during the warm and wet transitional weather periods. N-Serve also extends nitrogen’s availability in the soil so that it’s there in the spring when your crops need it during critical growth periods.