What is in this article?:
- Great drought taking toll on Oklahoma cotton
- Irrigation Termination
- Record breaking temperatures are still underway and based on recent forecasts will continue.
- It appears that we will have virtually no surviving dryland fields produce harvestable yield.
- Nearly all fields are ahead of schedule due to lack of rainfall, extreme deficit irrigation in many instances, and extreme heat.
Nearly all fields are ahead of schedule due to lack of rainfall, extreme deficit irrigation in many instances, and extreme heat. For example, when long-term average heat units from May 25 for Altus are calculated using the “normal” (30-year dataset encompassing 1971-2000) temperature data, the total is 1,904 DD60s through August 22. This year, based on Mesonet data from the Altus station, the total from May 25-August 22 is 2,700. This compares to having an additional 30-year normal (730 heat units) month of July squeezed into the growing season. The actual heat unit accumulation between May 25 and August 22 is about 42 percent above normal.
Most irrigated cotton is well ahead of schedule and at or near the mature stage when all bolls that will contribute to ultimate yield are set, especially those fields that had severe deficit irrigation compared to crop ET.When one considers the COTMAN 50 percent probability date of August 20 for a bloom making a mature boll, much of this irrigated cotton is “finished.”
For more discussion on the COTMAN program see the August 8th issue of Cotton Comments.
Crop ET has been excessive based on the environment (solar radiation, temperatures and wind speed) and crop demand. Using Tipton Mesonet station data for a May 25 planted crop, since August 1 the amount of crop ET has totaled about 9.2 inches.