Planting Winter Wheat into Dry Soil
9/12/2012 7:20 AM
Bob Fanning –
The recommended time to plant winter wheat in South Dakota, September 15 to October 20, is rapidly approaching. Unless they receive significant rainfall, most of the fields producers intend to plant into will be quite dry. Jim Shroyer, agronomist with K-State Research and Extension, reports similar conditions in Kansas: http://www.kansaswheat.org/news.php?id=652.
Winter wheat producers have been faced with planting into dry soil before, although this may be one of the most widespread occurrences in recent history. There are three options to consider, each with their advantages and risks.
One strategy is to plant wheat at the normal seeding depth of 1 1/2 to 2”, at the normal, recommended planting time (Sept. 15 to Oct. 20), and hope for rain. The seed will remain viable in the dry soil until enough moisture causes it to germinate and grow. If it appears that the dry weather will continue until the end of the recommended range of planting dates, producers should treat the fields as if they were planting late. To account for late emerging wheat, increase seeding rates, use a fungicide seed treatment, and use a starter fertilizer if needed.
This strategy does present the risk of a hard rain crusting the soil and/or washing soil off planting ridges and into the seed furrows, possibly causing emergence problems. There would also be potential for wind erosion as the ridges would be leveled. The wheat may not germinate until late-fall or spring, a situation that research has shown results in reduced yield compared to wheat planted and emerging at the recommended time. One of the worst results of planting into dry soil is if the seed gets just enough moisture to germinate, but not enough for the seedlings to survive if dry conditions return.
A second option is to use a hoe drill to plant into moisture, if possible, during the recommended planting dates. The variety planted must have a long coleoptile, a hoe drill is about essential, and there must be good moisture within reach. The crop should come up and establish a stand during the recommended time. The wheat and the ridges created by the hoe drill would help keep the soil from blowing.
Wheat planted deep normally has below-normal emergence, so seeding rate should be increased. If rain occurs before the seedlings emerge, some of the soil could be washed from the ridges into the seed furrow, increasing the depth to emergence even further. Increasing the seeding depth also extends the time to emergence. Delayed emergence means more potential for disease and pest problems and reduced tillering potential. It's also possible that the wheat would get planted so deep that it would germinate but never emerge. For information on coleoptile length of winter wheat varieties, see Table F on page 6 of EC774, Small Grains 2011 Variety Recommendations.( http://pubstorage.sdstate.edu/AgBio_Publications/articles/ec774-11.pdf)
The third strategy, wait for a rain, and then plant. Under the right conditions, this could result in good stands, assuming the producer uses a high seeding rate and a starter fertilizer, if needed. If it remains dry well past the recommended range of planting dates, the producer could choose to not plant winter wheat and plant a spring crop instead.
The risk of this option is that it may rain and stay wet until late in the fall, preventing planting the wheat at all. If the wheat does get planted late, research shows that on average, yields will be significantly reduced compared to wheat planted and emerging during the recommended dates. There is also the risk of leaving the soil unprotected from the wind through the winter until the spring crop is planted.
Crop insurance considerations and deadlines will play an important role in these decisions. September 30 is the signup deadline for winter wheat insurance. The planting deadline for full coverage, which includes winterkill coverage, is October 15. There is a 25 day late plant period, during which every day after October 15 the crop is planted, there will be a 1% reduction in coverage from the chosen level. The premiums remain the same, even though the level of coverage is reduced. Again, winter wheat planted after October 15 is not eligible for winterkill coverage. To clear up any questions, contact your crop insurance agent.