Government incentives aimed at mitigating climate change are almost sure to motivate you, and your landlords, to move toward no-till and cover crops. That’s the reason for our series of stories aimed at helping you convert to vertical farming systems, where those practices perform best.
As you prepare to plant your first crop in a vertical environment, whether it’s one field or a whole farm, keep in mind the 4Rs of fertilizer management — right product, rate, time and place — might be different from traditional horizontal, full-width tillage systems.
Residue might hamper phosphorus uptake. Surface cover slows soil warming. As a result, soils that test adequate to high in phosphorus might be deficient early in the spring.
“Corn will grow when the soil temperature reaches 50˚F,” says Farm Journal field agronomist Ken Ferrie. “But Farm Journal’s on-farm studies show phosphorus won’t become available in significant amounts until the soil temperature reaches 65˚F. That’s when soil organisms responsible for releasing nutrients start to become active. If young corn plants run short of phosphorus before that happens, ear girth will be reduced.
“You can prevent young plants from stalling by applying phosphorus fertilizer with the planter,” Ferrie continues. “The roots will begin to grow at 50˚F. When they reach the starter band, they will pick up the phosphorus even if the soil temperature is less than 65˚F.
“If soil tests high in phosphorus, and you wait for 50˚F soil temperature to plant, you might need only a low rate of starter in the furrow. But if you push planting conditions in cold soil, the in-furrow application will help, but it might not be enough to get to knee-high corn. You’ll need a higher rate, placed beside the row.”
Most cover crops raise the carbon penalty. As soil organism populations increase, due to an abundant residue food supply, they consume soil nutrients — nitrogen and sulfur, as well as phosphorus — making them temporarily unavailable to plants.
“In cover crop fields, you might want to apply a higher rate of starter containing all three elements,” Ferrie says.
N, P and S Placement Tips
“Place phosphorus where young roots can find it quickly because it does not move in the soil,” Ferrie says. “Left on the surface behind the planter, it won’t move down fast enough to provide a starter response. Brace roots will pick it up later, but that’s too far along in the growing season, and you will lose ear girth. Put higher rates of phosphorus beside the furrow and close to seed depth or a little below. That sets up a relay system that will keep plants trucking along even if soil temperature crashes after planting.
“Sulfate sulfur can be placed in a band beside the row or left on the surface, where it will move down with rain,” Ferrie explains. “Be careful putting sulfur in the furrow because it can burn the seed.
“Nitrogen can be applied on the surface at planting or incorporated by dragging a chain (but fertilizer may splatter onto the planter in windy conditions). There are many planter attachments that can slightly incorporate nitrogen, but they are too shallow for phosphorus. So, you may need two systems: one for applying phosphorus and one for nitrogen and sulfur. Or you can band everything 2" below the surface and 2" beside the seed furrow.”
How Timing, Placement Affect Yield
This on-farm Farm Journal study shows the potential reward, and the risk, from split-applying nitrogen fertilizer. Trials 1 and 2 were in Ipava silt loam and trials 3, 4 and 5 were in Sable silt loam. A total of 200 lb. of nitrogen was applied. In each trial, 30 lb. per acre of the nitrogen was applied with the planter. The study compared these treatments:
Applying half the nitrogen at the V6 stage always yielded more than applying all of it before planting. But applying half the nitrogen at the VT stage yielded less. “Two factors came into play,” says Farm Journal field agronomist Ken Ferrie. “First, waiting to sidedress at the VT stage caused the corn to suffer stress during the rapid-growth stage. The secret of high yield is to never let corn plants have a bad day. And then, illustrating the risk of delayed sidedressing, after we applied nitrogen at the VT stage, the weather turned dry. The late-sidedressed corn turned yellow and did not recover until it rained four weeks later, by which time the plants were in the R3 stage.”
Fertility is a Balancing Act
The trick to applying the 4Rs as you convert from horizontal to vertical farming is to use the most efficient product, rate, timing and placement without increasing total fertilizer applied. Besides good stewardship, following the 4Rs might qualify you for payments from incentive programs. Here are some ways to maximize fertilizer efficiency:
- Count starter fertilizer as part of your total application, not an addition to it.
- Broadcasting nitrogen and sulfur, in dry fertilizer or a herbicide carrier, reduces the amount of planter fertilizer you need to apply. However, a banded application at planting is at least twice as efficient. “You’ll see a bigger response to 30 lb. of nitrogen per acre applied with the planter than to 60 lb. per acre broadcast,” says Farm Journal field agronomist Ken Ferrie, citing on-farm studies.
- Apply a higher rate of starter if you’re dealing with cover crop or continuous corn residue to compensate for the greater carbon penalty. Following a dry fall, remember you will have more residue and a higher carbon penalty the following spring.
- Some incentive programs pay growers to reduce their nitrogen rate. Before enrolling, put out test plots to measure the effect. If you do reduce your total nitrogen rate, split your application to become more efficient. Test soil for nitrate at sidedressing time to make sure the crop doesn’t go hungry. “In many areas, the last several years have been friendly to low nitrogen rates because the weather has been dry,” Ferrie says. “Don’t get caught if the summer turns wet.”
- Be sure to apply enough early nitrogen to carry corn well into the rapid-growth stage. “The purpose of the nitrogen that we sidedress is for grain fill after pollination,” Ferrie says. “If you don’t apply enough nitrogen up front to supply corn well into the rapid-growth stage, it’s essential you don’t delay the timing of your sidedress application.”
