Here we are at the intersection between two crop years; some of you are still harvesting while others are getting a head start on laying the groundwork for next year’s crop. One of those operations is the application of Anhydrous Ammonia as a source of Nitrogen. Over the course of the next year, you will hear me talk more and more about the 4R’s of Nutrient Management given to use by the International Plant Nutrition Institute or INPNI, that being said, this operation really focuses on three of the four R’s. Right Rate, Right Source, and Right Timing. I am not saying applying fall NH3 is wrong; I am saying we need to consider all the variables that enter this decision.
First, we need to be sure that we are considering soil temperature when we are going out and applying NH3 in the fall. Today when I looked the CVA average over the course of the last seven days was 49.4o F, which is below the suggested temperature of 50 where the nitrification process is slowed considerably. The process of nitrification is the process of converting the NH4+ or ammonium form of Nitrogen to the NO3-form, and the majority of that process is done by two soil bacteria Nitrosomonas and Nitrobacter and this process is very Temperature dependent. But until the soil freezes this process never really stops, and even a cool soil can convert a considerable amount of Ammonium in a relatively short amount of time. As seen in Figure 1; even at a soil temp of 52 o F we can convert about 40% of the Ammonium in the soil in about five weeks, which doesn’t mean we have lost it, but it means the pool of Nitrogen that is at risk of loss is bigger. *More about pools of Nitrogen next week.
So how do we reduce that risk of Nitrification and our applied Nitrogen being at risk for loss while we are out there today? Well, we use some tools including some of those R’s that I had mentioned to make sure we are protecting one of the largest line items on your variable cost lines. One of those tools is the use of a Nitrification inhibitor as you apply NH3, for some of you this is already a decision you don’t have to make because it has been made for you. For the rest of you, it’s definitely an option as you head to the field. There are multiple options on the market, and none of them really work the same. I will explain the differences here another day… let’s just say it’s too complicated to include in this blog. However, they all have the same goal, to slow down the Bacteria by either killing it off or slowing down the reactions by blocking the enzymes needed to carry them out. We just harvested a spring applied trial using two of the products last week and even though it was spring applied and side-dressed the yield response was about 5 bushels per acre, so in the fall I would expect us to see about a 3-4 bushel increase over that. For more information see your local Central Valley Ag Field Sales Agronomist or Agronomy location or feel free to give me a call.
The other options require us to use a combination of those three R’s which long term in conjunction with using the inhibitor piece will really help us protect and utilize that investment. The Right Rate will require us to go out and take good representative soil samples, utilize all the credits that make sense to you and your operation, and take advantage of making sure we apply the right yield to your recs by using stable yield based VRN recs. The Right Source and Right Timing work together in this situation, I will not deny that NH3 is a very economical source of applying nitrogen, but it should be used in tandem with another source and timing to help keep the at-risk pool as small as you can manage while helping manage your bottom line. The addition of top-dress, side-dress or fertigation applications will help us feed the crop when its hunger is the greatest and more efficiently utilize every pound of N applied.
This article wasn’t written to get you to stop what you are doing, but it was written to start a discussion on how we can do it better, smarter, and more efficiently for the good of your operation. Like I said this journey about Nitrogen is going to be a lot about doing what is right, rather than what is easy, but mostly it’s just about doing it 10% better.