Nitrogen Application Considerations
Like corn, wheat is a grass, so nitrogen is one of the key nutrients that a wheat plant needs to grow.
The timing of a nitrogen application depends on
- the size of the plant,
- the stand (A good rule of thumb is that you need 25-30 plants per square foot),
- and when it was planted the fall before.
On our farm, we use a split application. If the wheat is planted at the optimum time and it gets to a good size, we generally will wait until March 1st to do our first application. If the wheat is small and is not tillered out very well going into winter, then we may put the first pass on in late January or early February.
We usually apply about 35-40 percent of the total nitrogen applied in the first pass, and then wait until the first week of April to go over it again with the second pass, which is usually 60 to 65 percent of the total. When considering a rate for your first pass, you need to consider the amount of fall growth. If you have a lot of fall growth, then you want to apply less nitrogen on the first pass or it could get too dense and lodge more easily. If the growth is less and the plants are small in the fall, then apply more to encourage tiller development. I would apply anywhere from 30 to 45 pounds of actual nitrogen.
For your second pass, apply the remainder toward the end of March or early April, depending on your stand, yield goals, and variety. I would apply between 60 to 80 pounds of actual nitrogen. You need to be very careful at the higher rates or it could lodge, which ruins the whole crop, including double crop planting. In certain situations, we use a growth regulator such as Palisade which shortens the plants.
The wheat needs nitrogen both early and later in case you have a wet season, so it’s more environmentally friendly to do a split application. By doing so, you avoid the risk of heavy rains or snow that would cause run-off.
We use stream bars to apply all liquid nitrogen for both passes on our farm . The reason we’ve gotten away from the spinner spreaders is because we can apply the nitrogen more evenly using liquid and the stream bars. We push nitrogen pretty high and if you overlap too much, it will cause lodging.
As I mentioned earlier, wheat is a grass so it’s important to also consider an application of sulfur. On our farm, we’ve seen good results from also applying Ammonium Thiosulfate (ATS) with our nitrogen in the spring. The sulfur helps with overall health of the plant. These days, soils are receiving less sulfur from air emissions, therefore the soil has less available sulfur to supply a wheat crop, so we add it. In my opinion, after Nitrogen, Potassium and Phosphorus, sulfur is the most important nutrient to the wheat plant.
We’ve also been experimenting with trying other micronutrients on our farm but have no definitive results other than the sulfur.
When it comes to herbicide, we generally use harmony or some form in the spring for the winter annuals. It’s also important to watch out for aphids. If you use an insecticide on the seed, you generally don’t have to worry about aphids in the fall but if you have an early, warm spring, you may have some aphids. It’s important to watch out for aphids and treat them with an herbicide since they cause barley yellow dwarf disease among other things.
If it’s a wet spring, we apply a stabilizer with the nitrogen in order to prevent leaching and denitrification in wet weather and to keep the nitrogen in place so that it’s available when the plant needs it. If you can tell we’re having a wet spring, then stabilizer and split applications are a good idea.
Dan Rubin is a fourth-generation family farmer. He farms with his two brothers in Fayette and northern Marion counties in South Central Ill. They grow corn, soybeans, wheat, hay, and raise and finish feeder cattle.