VR Nitrogen

VR Nitrogen from Central Valley Ag on Vimeo.

by Keith Byerly

by Keith Byerly

After another week of random rain, then finally some heat, it’s still difficult to focus on anything other than Nitrogen. By now, you’re probably getting tired of listening to everybody talk about the ways we need to verify our loss, develop a plan on how and when we will apply. BUT just because you’re tired of it, it doesn’t make it any less relevant or truthful. However, there is one important aspect we have left out to a degree up until now. That detail is addressing if Variable Rate Nitrogen is for you.

By now, I think we have talked about addressing our realistic yield goal, and fertilizing accordingly. The N.E.S.P. and the steps that our FSA’s are going through with you to discover our end goals are addressing this nicely. So then, as you consider your fields, what end result are we after? Have our plans changed and we need additional units of Nitrogen? If we do need additional nitrogen units, do we need the same amount uniformly across the field? Is our plan unchanged, and we are staying the course?

I believe I can make a pretty strong argument that no matter what this year has dealt you to date, that the time has come to have a more intensive Nitrogen Management Plan. That plan includes taking multiple things into consideration before the season starts, and then calling an audible as needed. As we look together at your field, we need to start below the ground and work up. A recent, intensive soil sample is the basis of what we are going to build upon. We need to have the soil tell us things like Organic Matter, CEC, and Soil Nitrate levels. These are the basis for the important part of what we do.


As you look at a piece of ground that you have farmed long term, I believe that you are fully aware that the yield variability you see on the field is the end result of a number of factors. Our cornerstone nutrients like, Phosphorus, Potassium, Sulfur, and Zinc are influencers without a doubt. But at the end of the day, a lot of our variability comes down to 2 factors, water holding capacity (soil texture and structure) and the ability to mineralize Nitrogen (soil texture). If we can use the soil samples to create a base map of how our soils respond from the ability to provide Nitrogen, then we have part of the battle won.

So back to something I said before. Yield Variability is a key in this process. Our yields vary every year because of a number of factors. The ACS Regional Specialist can analyze your yields and create a Yield Goal map that is based on stability of yield over time. This is the process we use when we are doing ACS Variable Rate Seeding. This variable yield map is step towards predicting our final yield, and an important step in identifying our Nitrogen need. Just like many other nutrients, we don’t believe that need is uniform across the entire field, so why should we apply the nutrient at the same rate everywhere.

At this point some of you are probably saying “Duh!” And you are right, we have addressed this variability for years with Variable Rate P, K, and Lime. But we have always shied away from Nitrogen for a number of reasons. Mistakes in the application rate are much more obvious with N than other nutrients, both in yield and visibly. So why now, why this year after all this rain. It has nothing to do with the year. The plan has been in place for months now to accelerate the adoption of VRN. The main reason being based around restrictions, environmental considerations, and pending use restrictions. This year’s rains have just brought the issue more to light. And just like you, we are having to adjust our prescriptions because of changes in yield goal, denitrification, etc.

At the end of it all, it shouldn’t be any surprise that we are advancing Nitrogen prescriptions ahead like we have done the other nutrients. It has taken more time because it is a complicated issues. A simple soil test doesn’t lead us as to a single number we can build upon like other nutrients. It is a multi-faceted approach that need soil testing, ground trothing, Nitrogen models, and other factors included to be successful. And VR Nitrogen fits into a urea application or, as we talked about last week, can be incorporated and used with the Y-Drops as well. I wanted to close with the old adage that a rising tide raises all ships, but with the rains in the month of May, perhaps that is a poor choice of words.