With the recent weather and lack of pre-plant N applied this fall I know a ton of rigs are running right now and I am handling a lot of questions about N rate, source, and time. So, while it might be a bit late I wanted to share a few thoughts.

First soil N: If you look back at the August 22 Blog, A Hiccup in the C cycle, well that cycle was put up on blocks for most of the wheat belt will late Oct. This had multiple ramifications, one; the summer crops suffered, two; mobile nutrients moved to the surface, and three; residue did not break down due to lack of moisture, the residue breakdown in turn ties up N into OM. These factors all resulted in above average soil test NO3 values. However, as I mentioned in that blog when the soils get moisture and warm temps that break down will ensue and short-term plant available N will drop until the OM mineralizes and releases NH4 sometime in the spring.

Second soil water: For most of the wheat belt the Mesonet is showing a concerning trend in soil moisture. The 16” soil moisture map looks pretty good with exception of the panhandle. However, if you look at the difference between the 16” and 36” you can see there is not a lot of moisture at depth. If we maintain these warmer temps the crops going to keep growing and burning through the moisture. Our ground is going to require a good dose of spring rains to maintain the yield potential.

If you have read much of my work you know my opinion, supported by years of research, on nitrogen timing in wheat. In my perfect scenario I go with a in-furrow application and then hold off on any additional N application until just ahead of hollow stem for wheat under the 75-bushel range. And for anything over that yield level I like a shot of 30-50 at green-up with the remaining at jointing. With both approach I am utilizing reference strips. This timing approach allows for adjustments, which I believe this season will be needed.

So for me the trick with this season to maximize profit will be the flexibility. Going all in early locks you down. For those who haven’t applied yet but are about to, you should consider adding a zero N check or two. The zero N will help you see if all that residual N is still there for if the organic matter cycle has tied it back up. Basically, if the zero N shows early, that means your crop is dependent upon you for its N needs. If you get to hollow-stem and that zero N is still not visible, Pull Back the Reins on fertilizer N, the system is providing a fair amount. In the Arnall Utopia, the N you don’t apply in the Zero can go elsewhere and now you have a N-RICH Strip. With both of these options we can figure out a N rate based on GreenSeeker readings. If you have interest in applying reference strips let me know, I am happy to help create the applicator files that are used in the fertilizer rig.

Of course if your fertilizer management plan is in a holding pattern, the now is a perfect time to apply your N-Rich Strip. I have several blogs and extension materials which help describe the process N-Rich Blog.

If you’re going to go without the reference strip, then I say hold the majority of the N until we do or do not get spring rains. If it rains, let her rip. If not your probably sitting better with the N not on the field. Take a few lessons from the last wheat crop, heavy N was often more of a problem than being short on N when we were so dry.

Questions or comments feel free to reach out via email or social media.

Brian Arnall, Precision Nutrient Management b.arnall@okstate.edu

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