Wheat should be seeded into a firm seedbed with good soil moisture.
By Robert Klein, University of Nebraska-Lincoln
Wheat should be seeded into a firm seedbed with good soil moisture. This is more easily achieved in no-till production systems where residue protects the soil surface. If the seedbed is loose and the seed will be placed in dry soil, delay seeding until there is moisture enough to firm the seedbed with a shallow tillage operation. Seed placed in a loose seedbed is one of the leading causes of winter injury such as winterkill and root and crown rot.
For tilled seedbeds (usually fallow) where the seed can be placed in firm soil at the correct seeding depth for the winter wheat variety, the producer's best option is probably to go ahead and seed even if the soil is dry and the wheat seed will not germinate until it rains. This reduces the risk of waiting for a rain in years that when the rains come, they continue to come and seeding may be delayed until after the desired seeding date.
Recommended Seeding Depths
The maximum depth a winter wheat variety with a short length coleoptile can be seeded is 2 inches in a silt loam soil. In extremely fine-textured soils with a high clay content, reduce seeding depth by 0.5 inch. In coarse-textured soils with lots of sand, increase seeding depth by 0.5 inch. For winter wheat varieties with medium length coleoptiles, seeding depth can be increased by 0.5 inch; for varieties with long coleoptiles, seeding depth can be up to 3 inches with the adjustment for soil texture. If the seed is planted too deep, beyond the elongation of the coleoptile, seedlings cannot emerge and the result will be a poor stand.
Seeding Equipment with Hoe Openers
For hoe drills and air seeders with hoe openers, traditionally used in tilled soils, good quality spear point or eagle beak openers usually improve performance. Hoe drills, especially those with wider row spacing, are able to place the seed deeper because they can build a ridge and plant in the furrow. However, producers must use a slower ground speed so adjacent rows are not covered with soil. The seeding depth then becomes the soil cover over the seed, not the operating depth of the opener. If the soil was not tilled too deep, it usually is possible to use the hoe drill to place the seed in firm, moist soil. Deep tillage or applying anhydrous ammonia with knives can dry out the soil, so it may not be possible to place the seed in firm, moist soil even with a deep furrow, hoe drill.
There are drawbacks to the hoe drill and the furrows it creates. The biggest is that if a hard rain occurs, the ridges will be destroyed and the seed, or developing plant, will end up under too much soil cover. In addition, the hoe drill does considerable tillage, burying residue which is best left on the soil surface to conserve moisture.\
Seeding Equipment with Disk Openers
Drills and air seeders with disk openers are becoming more popular, especially for no-till, as they require less horsepower to pull and have less soil and residue disturbance. However, seeding with a disk opener in a loose, tilled seedbed almost guarantees disaster unless it rains immediately after seeding. Leveling the drill slightly tail down, rather than running it level, will improve seed-to-soil contact by putting more pressure on the press wheels. However, it is difficult to firm dry soil around the seed and seeding should probably be delayed until there is moisture.
Before heading to the field to seed, make sure the opener disks on the drill or air seeder are not worn. On seeders with double-disk, seed-furrow openers, check to see that they are properly adjusted. On most drills individual disks can be adjusted inward as they wear by removing spacer washers from behind them. This keeps the two blades of the seed-furrow opener working together as one cutting edge. If the disks are worn without a sharp cutting edge, especially on single disk openers, replace the disks with new ones. This is critical in no-till systems to properly cut the residue and penetrate the soil.
No-till and the Benefits of Residue
For continuous cropping, use no-till production methods. When seeding wheat after soybean harvest, the soil should already be firm and tillage is not needed as wheat prefers the firm seedbed. If you do till, the seedbed will dry out to the depth of tillage. Also, tillage destroys the residue cover which should be left on the soil surface. The residue absorbs raindrop impact, reducing erosion and soil crusting, and keeps the sun and wind off the soil surface, reducing evaporation. Standing residue is also effective at reducing the problems with blowing soil and wind erosion.
- When seeding winter wheat this year, make sure the drill is running lower in back than normal to increase the pressure on the press wheels. Transfer more drill weight to the back of the drill and add extra weight to the drill. This will allow for penetration into dry, hard soil, forcing the seed into the soil and insuring good seed-to-soil contact.
- Don't seed wheat too shallow as the crowns will not develop properly and the seed zone will dry out too quickly. When using disk drills or air seeders, plant at least 2 inches deep to place the seed into better soil environment for germination and growth.