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Commentary: Early spring growth demands sufficient nitrogen and sulfur to optimize yield and quality.

Tom Kilcer

March 19, 2024

5 Min Read
A forage field
ON-TIME FORAGE: If you planted on time last fall and went into winter with 7- to 10-inch-tall material, you will likely see several benefits this spring. Tom Kilcer

Winter is coming to an end, and much faster than in normal years.

People I talked to in New York say they had less winter than we did in Tennessee. We saw an 8-inch blizzard — we rarely get 1 inch — and minus 9 degrees! We never get that cold this far south.

In any case, winter forage and grasses are greening up. This is one of those years where you should move early to get a jump on the season. The already enormous amount of spring growth demands sufficient nitrogen and sulfur to optimize yield and quality.

There are many factors that determine the best nitrogen rate to apply in spring. Recommended rates can be anywhere from 0 to 250 pounds of N per acre. You can’t change what happened last fall, but you can use it to determine the optimum N fertilization.

The first determining factor is when your winter forage was planted for your climatic region. If you did not plant two weeks before the wheat date, then you are not optimizing yield, so don’t overdo nitrogen. If it went into winter with 3 to 4 inches of fall growth, and you can see soil between the rows, you can expect 1.75 to 2.25 tons of dry matter. For 20% crude protein, 125 pounds of N — plus 22 pounds of sulfate — will be sufficient.

If it is smaller and has just individual spikes of green, save your money and plant the next crop.

If you planted on time and went into winter with 7- to 10-inch-tall material with solid cover and no ground showing between the rows, then you have realized two benefits: First, your spring yield potential could be above 3.5 or 4 tons of dry matter per acre. Farther south, like in Pennsylvania or Maryland, it could be well over 4 tons.

Secondly, research by Quirrine Ketterings of Cornell, as well as research I have done, shows that fall growth produces about 22% crude protein. At that height, you are looking at 1-1.5 tons of dry matter, which holds 65-105 pounds of nitrogen. This is because the excess manure applied the previous spring, before corn had sufficient organic matter, continued to release nitrogen after corn harvest and was captured by your on-time planting.

In our research in New York where manure was not applied, spring yields across all spring nitrogen applications went up as increasing amounts of fall nitrogen were applied to on-time-planted triticale. Spring yields increased when up to 60 pounds of N, plus sulfur (roughly 10 pounds), were applied in fall. As you move farther south, higher fall application rates may be justified.

Under high-yielding conditions, 3.5 tons of spring yield at 20% crude protein has 225 pounds of nitrogen. If 60 pounds were applied and taken up in fall, you would still need at least 160 pounds of N, plus 26 pounds of sulfur, in spring. For 4 tons of dry matter at 20% crude protein, you’re looking at 260 pounds of nitrogen, and the fall uptake may be closer to 100 pounds of nitrogen per acre.

Keep in mind that these suggestions are for winter triticale, which is shorter and denser than rye, and can produce superior crude protein without lodging. Also keep in mind that most nitrogen applied above what is needed for the winter forage crop will still be there for the next crop to get off to a quick start.

Continuous cropping is a very efficient nitrogen system. Our suggested mix for both cool-season grass, winter triticale forage and any other crop needing sulfur is 500 pounds ammonium sulfate and 1,500 pounds urea with an anti-volatilization agent. The latter is critical as winter forage and grasses have an enzyme that rapidly splits the urea into ammonia gas, which goes off. Untreated urea lost 63% more than treated urea in side-by-side replicated trials.

This mix of urea and ammonium sulfate produces around 1 ton that comes out at about 38-0-0-6S — 38 pounds of nitrogen in 100 pounds of mix along with 6 pounds of sulfur. If you need 125 pounds of nitrogen an acre for the crop, you would apply the mix at a rate of 229 pounds to get that 125 pounds of nitrogen.   

Harvest tips

Remember to harvest at flag leaf stage (stage 9), as this is where the flag leaf has unfolded but the head has not emerged yet. Stage 8 does not have higher quality than stage 9, and it had a 35% yield penalty from harvesting too soon.

If temperatures are normal to warm, push to harvest at stage 9. Conversely, if it is at stage 8 and you have a sunny day, and then a week of rain forecasted, get it cut so you have quality forage.

Further work by John Winchell of Alltech has fine-tuned this prediction. When the head is 4 inches down (flag leaf may be coming out), you have three to four days to crunch time. If the head is only 1.5-2 inches down, you need to move now. Any delay will decrease 12-hour digestibility. The 30-hour digestibility starts to drop at a slower rate, and then it crashes down as the head emerges.

It is better to be early than late to produce forage for your high-producing groups. Planting in fall a week earlier gains three days earlier harvest in spring. South-facing, well-drained soils will be ready sooner than north-facing, poorer drained fields.

You can open the harvest window further by planting an early-maturing variety first, and then a later-maturing variety later.

Kilcer is a certified crop adviser in Rutledge, Tenn., formerly of Kinderhook, N.Y.

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About the Author(s)

Tom Kilcer

Tom Kilcer is a certified crop adviser in Kinderhook, N.Y.

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