Small grains should have some nitrogen, most of the phosphorus, and possibly some potassium in the fertilizer band at planting. The higher nitrogen guidelines in each range are for the shorter, stiffer-strawed varieties; use the lower nitrogen rate on the taller varieties. When attempting to achieve near-maximum yields of wheat or barley on well-drained soils and when diseases can be controlled, the nitrogen rates can be increased to 80 to 90 pounds per acre.
These guidelines are for situations where lodging is not expected. Reduce the rate of nitrogen shown in Table 5.5.1 by 10 to 20 pounds if lodging is sometimes a problem and by 20 to 40 pounds if it is usually a problem. It is generally not a good practice to follow a sod with a small grain because the nitrogen released from the decaying sod can contribute to excessive lodging. When considering manure application options, the nitrogen from manure is generally more effectively used when applied for corn, sorghum, or other long-season crops than for small grains.
Winter wheat and barley should have 10 to 20 pounds of nitrogen applied in the band at planting, and the remainder should be applied in early spring after the crop has begun to grow and is in the tillering stage (GS 3 to 5). Ideally, nitrogen topdressing should be applied when fields are dry, not to wet or frozen ground.
Spring oats or barley can be seeded with all the nitrogen in the band, but more efficient use of the nitrogen can be obtained if some is topdressed in late May or early June. To reduce nitrogen loss from volatilization of ammonia from surface-applied urea, consider using a urease inhibitor. See nmsp.cals.cornell.edu/publications/factsheets/factsheet45.pdf for more information on urease inhibitors.
Crop sensing technologies can aid in within-field management of nitrogen for small grains. Such technology requires the establishment of an N-rich strip in each field or for each variety or soil management zone within a field, and development of local algorithms.
If the small grains are to be forage seeded, a larger quantity of phosphorus and potassium is required. Note the difference when forage-seeded and seeded alone in Table 5.5.1.
The soil pH for oats should be about 6.0, whereas the pH for wheat and barley should be 6.3 or above. The soil pH of a small grain seeded with a legume forage should be 6.5 to 7.0. Also see the general information section under "Soil Testing" Section 2.10.
Lodging Control in Wheat or Barley
Dense stands due to high seeding rates, high soil fertility levels, or excessive fall or early spring nitrogen fertilization rates weaken the lower internodes of the crop and increase its risk of lodging. If the variety or the field has a history of lodging or if the crop appears too tall for the stage of growth, a growth regulator can be applied. Cerone is currently registered on wheat and barley. It is recommended for use only if the yield potential of the crop is high and there is lodging potential. In this situation, apply 0.5 to 0.75 pint of Cerone Plant Growth Regulator at GS 8 to 9 (see Growth Stages of Cereals figure under Growth Stages section). Once the spike or head has emerged from the boot, a Cerone application will reduce yield, so do not apply after GS 10.
- Estimating Fall Nitrogen Uptake by Winter Cereals - NMSP Factsheet #88