The VRN question

May 10, 2018


Every year as we find ourselves having our corn planted, or hopefully nearly planted, we start to focus on what is next for our corn crop. For as long as I have been with CVA, my group of growers that I have “always” worked with in the North have been splitting their Nitrogen applications up and applying a portion of their Nitrogen in season. In the past few years, it makes me happy to see so many of you in other areas that now do in-season fertilizer to split up the feeding of the crop. Last week, I talked about Nitrogen volatilization, and so this week, I thought it would be a natural progression to talk some about the rate that we choose to apply.

Many Agronomists have been apprehensive to talk to growers about Variable Rate Nitrogen for two reasons; nothing looks worse than yellow corn plants, and a few more units of Nitrogen is relatively cheap insurance. Especially when you consider that choosing a rate in the first place can be a bit of a challenge. If you look at the Nitrogen Rate Equation for corn, seven variables go into making a Nitrogen rate decision. At days end, we can end up with a rate from less than 3/4ths a pound per bushel to over a pound per bushel. So, is it worth doing a variable rate application of Nitrogen this year?

The VRN Question from Central Valley Ag on Vimeo.

But to further complicate the question, how do we go about deciding a method for VRN? For those of you that take Nitrate tests each year in our zone sampling program, you have Nitrate test that changes some of our credits and affects our N rate that we can manage. Some people look at their application of other Nitrogen sources like manure or variable rate nutrient applications like Phosphorus and simply make a map that credits the Nitrogen in those products. These are great starts, but I am confident in this day and age that we have the ability to do much more without a ton of extra work.

Last year was further proof to me that the VR Nitrogen prescription process that our ACS Mangers go through to build prescriptions for your operation are unmatched in the industry. With EC data and soil samples married to the Variable Yield Goal, I think we can develop a plan that accounts for your variability in yield, and your variability in soils. For those of you that don’t already have all of your nitrogen on for the season, I want you to think about the remainder of what you have to apply. For those of you that will be using anything other than a center pivot, we have an opportunity to vary our Nitrogen rate yet this year.

What I really want you to consider is that for the most part, we already have the pieces we need to create a Variable Rate Nitrogen application for the remainder of your Nitrogen needs this season, and most of us have a system that is controlled via a display in our cab. For those of you that have all of your Nitrogen applied for this year, I want you to file this conversation away in the memory banks for harvest time. I will always be a fan of the advantages of a split application. But, if you apply anhydrous this fall, that is also a prime opportunity to apply our Nitrogen variable rate.

So the take-home for you today is simply this. VR Nitrogen is an opportunity to dial in the right Nitrogen rate for each of the different areas in your field. If we are doing variable-rate seeding on your field, then matching Nitrogen rates to yield goals is going to be quite simple. But even if we are not doing VR seeding yet, that doesn’t mean that VRN is out of reach, as long as we are working on our other fertility needs and doing the soil sampling we should be. Working with your Agronomist and your ACS Regional Specialist, we have an opportunity to put a custom plan in place for your operation. One that usually improves your Nitrogen use efficiency and profitability.
by Keith Byerly
Posted: 5/10/2018 7:52:43 PM by | with 0 comments