Dry Soils and Nitrogen Application. What should I do?
Welcome back to JJ in the field, I’m your host, Jonah Johnson. So, we are dealing with dry conditions. Water is evaporating from our soils; corn is at sidedress, top dress height right now. Growers are trying to continue to work in the fields, obviously. Today’s question revolves around, should I keep adding nitrogen to the soil, considering how dry is?
We all know we need moisture for mass flow from the nitrogen source to get the solution to move into those root zones so that plants can uptake that. If you look at the field behind me, obviously it’s a very dry situation. Dry soils planted around May 20th had very little rain and the corn has kept growing and emerged and has been growing surprisingly fast, which is telling me, and perhaps in your own situation, that the corn’s found moisture enough for it to grow.
Considering that there is moisture below our feet currently right now, if you dig down you will find some moisture. And if we’re side dressing or top dressing, our nitrogen application right now, that’s something we need to really consider. What does it cost you if you shut down right now and then apply any more nitrogen?
If we break this down, there are two camps. Are you injecting below ground or are you applying on top ground? So, if we first talk about, we’re putting nitrogen, whether it’s a UAN solution or anhydrous ammonia in the soil, think about if you are injecting right now that you’re getting below the ground, probably anywhere from 3 to 6 inches.
And chances are the deeper you go, the more moisture we’re going to find that will begin to go into a solution with the soil moisture that is there. So obviously, the UAN is a solution already and it gets diluted and goes into a mass flow situation, once it gets moisture, that will become available to our plants once those roots get to that band.
If you’re a Y-dropper right now, some guys I work with either Y-drop when the plants are younger, they may wait on the corn, get some height to it and go and Y-drop or there’s some application coming out there that has the ability to inject in the center and Y-drop at the same time or vice versa.
Consider again UAN is a solution and that will go in those plants because if you think about it, you’re putting that band right on top of the root zone and that linear cornrow, and that will get into the plant initially because its placement is so much closer via band. I encourage you to keep trucking, if you will, right now with our nitrogen application, because as we have moisture, obviously if we don’t get a rain, that moisture is going to start to diminish.
And if we can get that nitrogen in solution, it won’t go anywhere because the nitrosomonas, nitrobacter bacteria in the soil. They’re going to be dry too. And they won’t be as active as breaking down those nitrogen sources. The urea and the ammonium component of in the UAN is going to be quite stable on its own.
And then the nitrate fraction, which is going to be really up-takeable, those are all about to go in the solution and be available to that plant quickly. But we’re not going to lose those because we’re not in a situation where we get into a denitrification or ponding type situation that would encourage leaching. So, keep that in mind.
Anhydrous ammonia, that’s going to be a stable source regardless as it goes in the soil. Obviously, we’d like to see a little bit of moisture to seal that application slot, but again, you’re injecting that quite deep, typically seven or eight inches unless you’re using a high-speed toolbar. In those deeper situations, again, we will find moisture enough to seal that and retain that nitrogen around for those plants.
So ultimately the situations that I’m listing, what we don’t want to happen is that corn plants start to bolt and then either we can’t get back in once rains do return if we get into a very wet situation because, obviously, that that’s a bad day. If we can’t supply nitrogen in a timely order. The other side of the fraction is guys that typically top dress their corn.
Whether you’re using a urea or AMS type product, ammonium sulfate is going to be a very stable product on its own. The sulfur proponent in that fertilizer essentially gives you a time delayed release. The sulfur has to be oxidized in the soil for that sulfur and ammonium to be released or the sulfur protects the ammonium of the nitrogen proponent.
I don’t have concerns about that on the refraction, whether you’re using the blend or urea by itself. I do encourage you to use a NBPT stabilizer on your application because as you can see, hot, sunny days, intense sunlight, lots of U.V. light, it’s going to be penetrating and warming the soil surface that will break those urea pearls down very quickly.
Then there’s been a questions asked about, well, what about the urea enzyme, which is a naturally occurring enzyme on the in the soil and in biomass that initially starts to break urea down? Does that need a lot of moisture for that that process to begin? And the answer is, it does need moisture. But my concern is, the bright sunshine and the winds is going to start breaking that down and make that release ammonia up into the atmosphere if we don’t protect it.
My encouragement to you considering top dressing corn right now, I think we need to break that application in two camps, whether you have the opportunity to apply on your own or not. So, you have a spinner spreader machine or your own spreader where you can get over your own crop in a timely order. Then you have time, and you could apply at your own pace.
Now, for a lot of us who depend on custom application, whether it’s from Sunrise or other vendors across Ohio, there’s a big concern that if we do, if you guys wait till the last minute when a rain is in the forecast and everybody does that, there’s just may not be enough physical time and manpower and equipment to get the application on when you want it.
I would like to encourage you to consider still applying your products right now, because if we don’t, we get in a situation where the corn is going to bolt and either we can’t get over it and make as accurate an application as possible. Because the taller the corn gets, it’s going to essentially interrupt the perfect distribution that’s coming out of the back of a spinner spreader machine.
If that’s not allowing a perfect spread on the width of that machine, then we can encourage some parts of the field that may not get the rate that was prescribed for it. So, keep that in mind. Also with that, you know, if we get wet, we get rain back in the forecast and it stays wet and then the corn keeps growing, we may not get in there in a timely matter and trying to get an airplane to spread urea or a helicopter, or finding someone with a high clearance machine, whether it’s Y-drops dribbling down the center row, that’s never a good day and could be another headache.
So that’s why I bring these points to you, for you to consider on your operation.
Lastly, if you have crop insurance, keep in mind that if you’re protecting your revenue through that investment that you know we’re still going to have a great opportunity for a good crop this year. There’s been very few years in the past minus 1988 was probably one of the worst years if you if you can think back that far. But even in 2012, when we had the most recent really severe drought here in Ohio, we still had corn that yielded, we still had crops that came up and maybe not perform like we want them to, but my point is that there’s very few years where we had a complete failure out there. So, we still want to try to do the best we can for the crop we have out there.
If you have further questions, please reach out to any of us within Sunrise, your ASAs, anybody on the PCT team, including myself we would love to help walk you through your scenario and hopefully help you with some technical advice to address your specific need on your farm.
Take home message is I think we need to keep applying our nitrogen, whether it’s side dress or top dress.
Watch JJ in the Field: Dry Soils and Nitrogen Application. What should I do?
Don’t let your soybean field retreat too easilyThe death of a soybean plant follows a pre-determined path. You first notice a few yellow leaves on plants. Then several more yellow leaves follow with the leaves rapidly falling off the plant. At this time if you walk through a soybean field if you touch the petiole still attached to the stem it will break off the plant with just a light touch. Stems go next.
The plant is simply digesting all available starch and minerals remaining in tissue in order to maximize grain fill. When we hear complaints of green stem in beans at harvest this typically is associated with higher grain yield as the soil was able to mineralize more nutrition late season and provide beans a more peaceful end.
Later this summer, soybeans in their early reproductive stages will similarly march toward
self-destruction, believing the short-term goal of filling seeds is aligned with your broader production targets. Soybeans will sacrifice roots and abandon nodules at late V5 and V6, cutting off nitrogen supply. Leaves, unable to maintain protein, will lose photosynthetic capabilities and, in turn, be cannibalized to fill beans. Yields will retreat from what they could have been if they had better command of the plant’s resources.
Plant development must include a balance of resource allocations. Some resources should be used for immediate needs, while others maintained for future plant needs.
In the soybean plant at R3, a balancing act should occur with sugar. The plant has an immediate need to develop pods and nourish developing seeds. At the same time, the plant must invest in roots and nodules for nutrient uptake and nitrogen fixation to produce new leaves that make sugar to fill future pods and seeds.
However, too often at R3, a soybean plant fills the first seeds and invests in the future. It doesn’t maintain roots. It doesn’t make new leaves. It raids nutrients from existing leaves to move them to seeds. Early-setting seeds, seize all the sugar they can get, then release a barrage of hormones that force pods to abort.
A soybean plant exemplifies this poor strategy for two reasons. As a legume that requires far more nitrogen than corn for grain fill, it’s decision to prematurely stop support for the roots and nodules that supply this nitrogen has a dramatic effect on crop yield and quality. Secondly, soybean yield is not determined early, like corn. Late-season behavior continues to affect seed number and yield.
What can be done about it? As growers we may better command these processes with soybean finisher products that improve crop growth and seed production. Unlike many other yield-improving practices, these new technologies are deployed later in the season, instead of being crammed in with other early-season applications.
Our most fundamental tactic is to ensure soybeans have adequate nutrition. Potassium, manganese and boron are critical in maintaining leaf tissue and the adequate movement of sugars throughout the plants. Micronutrients are best fed through the leaf; in dry soils, foliar potassium is important.
Supplemental nitrogen can be used and may increase the amount of nitrogen as protein harvested with the crop. Beans use about 6# of N for each bushel produced. However, mid to late season N applications have been highly inconsistent providing return on investment.
Plant growth regulator gibberellin will help facilitate sugar movement to roots, while auxin and salicylic acid (aspirin) will suppress production of ethylene – a gas that triggers plant stress responses, including leaf senescence (death). Properly timed foliar fungicides have also demonstrated ability to reduce ethylene senescence as well.
In the future, the solution to soybeans that mature too soon may be to “apply two aspirins and call me when your bin is full.”
Progressive Crop Technology offers a late-season nutrient product, PCT Soybean Finisher to consider.
Learning about nutrient availability from tile linesAs wet weather continues this season, the positions of tile lines are abundantly clear. Crops over those lines are darker, larger and more robust than crops between the lines. This variation illustrates differences between the presence and bioavailablity of nutrients.
A soil test measures the concentration of available nutrients per unit of soil. Many (arguably, too many) years ago, the relationship between crop yield and nutrient concentrations were quantified; these relationships continue to be the basis of modern recommendations.
However, adequate nutrient test levels do not guarantee availability throughout the season. Compaction and dry weather can limit root growth, nutrient solubility or even movement within the plant.
This year we can see how excessive moisture is depriving plants of the oxygen and energy they need to concentrate nutrients in roots. With the exception of well-drained sections over tile lines, plants are pale, stunted and starving.
Presumably these fields received fertilizer at either a straight rate or a variable rate that matched fertility with production goals. Either practice should have ensured enough nutrition for plants across the field. But while nutrients are present in adequate amounts, they are not bioavailable to plants lacking in oxygen and energy.
When soil-based nutrients fail due to excessive or limited moisture, foliar feeding bypasses the soil so that nutrients directly enter the plant. While these few pounds or ounces of nutrition don’t replace the hundreds of pounds of soil-based nutrients consumed over a growing season, they buy time until weather returns to more normal patterns.
While wet fields may not be accessible with foliar fertilizers, this is a great time to reflect on the relative advantages of foliar- and soil-based nutrition.
