“We went with what we read in magazines,” recalls Albion, IA farmer Wade Dooley of his first experience growing cereal rye for seed: “We didn’t fertilize it; you can grow it and it will be fine. That’s what we did. There is no doubt that you can grow it, but you won’t get good yields and expect uniformity in the field if you do.”
Even though wheat, oats, barley, and rye don’t need as much fertilizer to grow well as corn, a lack of fertility can cause lower yields, lower grain or seed quality, and field variability that can lead to weed and harvest headaches. As a bonus, a well-nourished crop is better able to resist disease, which could save you money in the long run. NDSU Extension Soil Specialist Dr. Dave Franzen joined our February shared learning call to discuss the ABCs of small grain fertility.
Rates and Timing of Nitrogen Application: A Managing Act
Winter wheat does not have the same tolerance for nitrogen overuse as corn does. Even if it results in a financial setback or a negative impact on the environment, the yield isn’t adversely affected. Winter wheat that has received an excessive amount of nitrogen will succumb. In addition to having a difficult harvest, if the wheat crop lodges before flowering (typically in May or June), you may also lose yield. In taller small grains like oats, rye, and triticale, this problem can be even more pronounced.
You must approach your fertilizer program with a keen eye for detail because of this delicate balancing act. Crop rotation is a good place to start. Do legume crops, such as soybeans, provide a nitrate credit? When planting a winter small grain in the fall after soybeans, these credits are especially useful because they don’t take into account the soybean N credit. Flattening may occur if you use the wheat N rate recommended by your state. Consider adding manure to the mix. The best way to know how much additional fertilizer you need is to have your manure tested.
We’re talking about removing three-quarters or eight-tenths of a pound instead of the typical one-pound removal from corn, oats, or wheat. To allow for higher N applications, wheat cultivars have been bred to respond favorably to N in the interstices of the grain. In contrast, crops such as oats, rye, and triticale are unable to tolerate high N rates in the absence of accommodation.
Your local conditions, particularly the level of organic matter in your soils, have an impact on the precise N rate you should aim for. However, even state recommendations should be taken with a grain of salt. Use the maximum return to N rates rather than a yield goal when calculating nitrogen rates in North Dakota.
The right time to apply nitrogen is also a balancing act to be considered. There are some who prefer to apply some nitrogen in the fall, but this practice can be dangerous. To avoid winter kill, we don’t want the wheat to become overly vegetative before the winter. The wheat can withstand snow and cold when it hasn’t grown much and isn’t yet too big, but nitrogen application can make it too vegetative and make it less hardy.
Manure and other organic fertilizer sources, on the other hand, release N at a slower rate than chemical fertilizer N. Composted manure, for example, has a high C:N ratio, so putting it out in fall can give it time to mineralize and become available to plants. To get the manure to break down, apply it in the fall if your state and land allow it.
The best time to apply fertilizer to increase yields is in the spring. It is possible to increase your yield potential by increasing the number of seed heads on a given surface area by applying nitrogen at this point in the process of tillering and jointing.
As for the amount of N that should be applied in the spring, a University of Kentucky resource for fertilizing winter wheat is recommended by an expert. It explains how to determine your plant stand (number of plants per square yard or per square foot) and when to apply nitrogen based on the results. Another option is to add 30-50 pounds to a strip when applying your spring application, which is usually done fairly early in the season. Your rate was probably fine if you didn’t notice any noticeable difference in the appearance of that area.
For spring applications into a growing small grain crop, urea treated with NBPT urease inhibitor or a stream of 28 percent liquid are two options. urea. The efficacy of the active ingredient and the rate per ton of urea of the original NBPT product AgrotainTM has been thoroughly studied, and it is nearly 100% effective in inhibiting ammonia volatilization. Urea was mixed at a rate of 3 quarts per ton with the product, which contained 26.7 percent NBPT.
If you use NBPT in a product today, you need to make sure that it is applied in the same way as the original formulation.
Spreading 28 percent fertilizer over small grain foliage is a bad idea because of the fertilizer’s high burn potential. A 28 percent stream reduces burn by a great deal if the fertilizer stream is not broken up by wind.
In particular, custom applicators may not be accustomed to avoiding doubling up on their passes, especially at the ends where shut-offs are not as quick as they should be. Pay attention to fertilizer application practices. While Wayne Koehler, a farmer near Charles City, Iowa, uses my fertilizer to fertilize his rye and oats, I make a point of reminding the applicators who apply it each year to avoid any overlap or double placement when they’re turning around.
Phosphorous: Start Applying As Soon As Possible!
Another essential nutrient for small grains is phosphorus, which strengthens roots and shoots, promoting winter hardiness and preventing lodging, while also enhancing the plant’s ability to resist disease. The application of starter phosphate during small grain planting is something Dave strongly believes in, especially for winter small grains. Dr. R.J. Goos, a longtime colleague, studied phosphate (P) for over two decades. Wheat will respond to a row-starter even at high soil test P values, especially in the northern plains, according to his recommendations. In addition to boosting the plant’s vigor, a pre-planting application of winter wheat fertilizer helps ensure a healthy crop in the spring.
If you are using a planter, the amount of fertilizer you can apply at planting will be limited.
Potassium, Sulfur and the Rest of the Alphabet
Unlike corn, wheat does not respond as well to potassium as soybeans do. Measurement of potassium (K) in the soil can be done with accuracy by performing soil tests, and if additional applications are required, these tests will reveal the required dosage. Chloride is commonly found in K fertilizer (Cl). Soil test Cl values are likely to be high enough to achieve maximum yields in areas where potash is regularly applied.
Potash fertilizer is rarely used in the northern plains, so soil test values can be extremely low. It is only when small grain prices are high and potash prices low that farmers should consider using Cl to boost wheat yields. In some parts of Indiana and Michigan, manganese has been a problem in the past, but this is a rare and unusual element to be concerned about. Copper (Cu) may be a problem in peat and muck soils with organic matter content greater than 10%, but if the organic matter is lower, it is a very rare problem. Deep sandy soils with low organic matter in North Dakota are of particular importance, and their value is extremely site-specific.
In contrast, our understanding of the importance of Sulphur (S) to small grain performance has increased. You have to mention North Dakota’s S deficiency because it is so widespread. A lack of S is especially harmful to canola, corn, and small grains. It’s a shame that soil tests can’t tell you with certainty how much S is present. Early in the season Tim Sieren, a member of the PFI, took tissue samples of his rye and discovered Sulphur and Boron deficiencies. To our fertilizer plan, we’ve added Boron and Sulphur. With a yield comparison, we saw a difference of 10 to 15 bushels per acre depending on the type of soil in which it was planted. That’s the best response I’ve received from any rye fertilizer. If you use sulphur as a fall fertilizer, you’re wasting your money.
Sulphur can be applied as a sulfate or thiosulfate, depending on the soil moisture and slope. It’s a waste of time to use element S. S fertilizer works best on sandy soils, hilltops, and slopes, especially when they’ve been wet in the fall or spring.
