For all of you who now have the song by Europe stuck in your head, I apologize. But the truth of the matter is, the proverbial light at the end of the tunnel is out there now. We can see the end of the irrigation season. It’s so close that we want to reach out for it. Maybe even take that leap and just get there. But, I am here to caution you that we aren’t there yet.
So if we aren’t there yet, then where are we? I wish I could tell you, but that’s going to vary a bit by planting date, weather, and hybrid. But what I can talk about is how to figure out where we are. There are some great resources out there that help with this task. And to be honest, a great place to get most of those is from UNL’s CropWatch site (cropwatch.unl.edu/gdd-etdata). From here you can look at the Useful to Useable Corn GDD tool. Here, you can put in your specific info to get a very close accumulated growing degree day calculation, projected black layer, and other info. But truly it’s what you do with this data next that turns it into something useful. Your FSA has a worksheet that I have shared with them that puts the pertinent info in one place. Here is the cliff notes version. If you look at your accumulated GDD’s, you can reference that to a pretty specific growth point; then you can take that info, and look to see how much moisture is needed to finish the crop. For most of us right now, we are looking at something around 3” to finish our corn crop.
For soybeans, it’s pretty much the same process, scout and accurately determine your growth stage, then reference the chart to find out how much water we need to finish our beans. A point I always like to draw attention to is that when our beans start turning yellow, they still need 2” of water to finish out.
In fact, with either corn or soybeans, a pretty good rule is that the last 2” of water contain 10% of your yield. By my math, that means the last 2” of water cost is $18-$20 and hold $55+ of yield on corn and $35+ on soybeans. Looking at it like that, you can see how costly giving in to that urge to shut off too early hurts your pocketbook.
So one more time, I am going to urge you to look at your probes and talk to your FSA or ACS specialist. We want to start pulling the moisture down to the bottom of our management zone, but we also don’t want to go there too early. Make sure if you do need moisture now, you are pulling the root line all the way down to the management line before you put on water. And if you do need to irrigate, I would rather put on 0.60” than an inch. As we approach the end, 0.60” is 3-4 days’ worth of moisture, and gives us plenty of time to evaluate if we need another round or not.
These first two weeks of August can swing our bottom line $50 fairly easily. I challenge you to not give in to emotion or frustration, but instead to let Agronomy be your guide. My team and I are always available to help, just give me a call or shoot me a text.