Sidedress Fertilization Is it only Nitrogen you should be applying?
Published June 13, 2020 | By Mike Petersen
Image Above:
Applying liquid products with Orthman cultivator during sidedress and ditching process.
Good question for all of you that are getting after the duty of sidedressing or fertigating now that the corn is climbing towards the sky like in the story of “Jack and the Beanstalk”. The demand from corn plants DNA signals is about to “hit the gas” on N consumption. You all are aware of that whether you are a rainfed farmer or an irrigated farmer, but what about potassium, zinc, sulfur and even phosphorus? Have you sampled with plant tissues to get an up-to-date view of how the plant stands with existing soil conditions and what you fed it earlier? Yes there is a cost to that, yet folks in the days we sit in with low commodity prices a full awareness of your crops nutrition has much value to fall time results. Sure we want to get by and hope for the best. I get that, but even though prices look pitiful would you stop feeding that hungry teenager who fades 20 minutes after lunch and looks like he will gnaw on your arm while you haul gated pipe off the trailer and onto the ground and shove them together? Inside joke I know for the rainfed grower in Iowa, Illinois, Indiana or other states that have not irrigated with 8 inch pipe. Just the same folks, we do not stop feeding a crop. Having a good idea where one stands sets the stage for the hybrids of today to do well or just so-so.
We at Orthman have teamed up with some great partners to study what happens to resurrect a farm that was less than optimally treated for some time nutritionally, old traditions of dosing with big amounts of N up front and little or nothing throughout the season was the game plan. We soil sampled before we strip tilled and placed nutrition and the soils were quite depleted, that literally made me gasp some. All that is to say now we have tissue sampled and found with the soils just warming into the temperature range in the upper 10 inches for the microbes to assimilate, populate and release nutrients as well as the early root system proliferate the soil profile. We are still a bit shy of what should be a sufficient to adequate level but we are responding with two sidedress operations.
Soil temperatures last week (1st week of June) were touching 70 degrees F. at 8-9 inches below the surface. That says what to you reading this? A large cross section of the microbial population is getting into the mode of working, eating, populating, dying and cycling. The nutritional products we laid in at 6.5 inches is right in that zone where we observed the 70°F are poised to and is being utilized and made available in the form most readily taken up by the young root system. Those old decaying roots are food for the bacteria, earthworms, other microorthopods, spiders, and such to breakdown organic carbonaceous materials, unlocking nutrients. All that being said, now is the time to supply N to feed the microbes but not over-feed them to take the crop towards its fruiting stage and kernel set.
In the field these last two weeks I have observed yellow striping in the corn at V3-V5. It is not zinc but sulfur for many plants. Sulfur as I have written on this blog plays a key role in photosynthesis and protein movement within the plant. May I suggest you get out and take a close look in your fields and before you finish every field in the sidedressing with 32% or 28% or even anyhydrous – to evaluate for sulfur needs. From here at the V4-V6 stage to V10 the call for sulfur is not huge but quite apparent to top production. You purchased >$300 bag corn, please be wise about how sulfur is critical to what the rapidly growing plant needs.
Yes Nitrogen is needed; please take into consideration the important secondary nutrient – S. We at Orthman also realize that many of you are using cultivators. Truly, a super time to place some of your total N and S fertility program — up-close and personal to the growing crop. As you do the plant will very likely respond within 2 to 4 days with a color change and growth. As it does the on-off switches inside the xylem and phloem tissues go on! Cultivating not only for pesky weeds, the feeding of the hungry teenager makes for a better ending to the last part of the yield game plan. I don’t know very many of us that walk away from well earned , hard fought and planned victory in the fourth quarter without a big smile. A story of the fourth quarter success: A tough quarterback in a post season game behind by six in the last few minutes with the ball on 6 or 7 yard line said “we’ve got ‘em right where we want ‘em”. He marched the team 94 yards and crossed the goal line for a touchdown and a win, later a Super Bowl ring. Some may remember that team.
You got ‘em right where you want those plants.