A drier pattern has dominated September in the western parts of Kansas (Figure 1). In the majority of the wheat growing regions, namely central and western Kansas, this was accompanied by warmer-than-normal temperatures and windy conditions. Therefore, estimated root-zone soil moisture is relatively low in the west as compared to eastern Kansas (Figure 2).
Figure 1. Total cumulative precipitation for the period between September 18 and 24, 2019. Map by K-State Weather Data Library.
Figure 2. Total soil water storage in the root-zone (top 20 inches (50 cm) of the soil profile) as of September 25, 2019. Map by Soil Water Process Lab using data from the Kansas Mesonet.
Weather Forecast
The weekly quantitative precipitation forecast for Kansas indicates that the probability of precipitation for the next seven days exists for totals ranging from 0.1 inches in southwestern Kansas to as much as 7.00 inches in the eastern portion of the state (Figure 3). Northwest Kansas might miss out entirely on precipitation. Despite the drier profile in western Kansas, the 8- to 14-day forecast (Figure 4) is favorable and might bring much needed moisture for a good start to the wheat-growing season, although the eastern third of the state is likely to face excessive moisture issues.
Figure 3. Weekly precipitation forecast as of September 26, 2019 by the National Weather Service Weather Prediction Center (NOAA). Precipitation probabilities in Kansas for the next 7 days range from 0.10 to 7.00 inches.
Figure 4. The 8- to 14-day precipitation forecast as of September 26, 2019 by the National Weather Service Weather Prediction Center (NOAA). Precipitation probabilities in Kansas for the next 7 days range from 0.10 to 7.00 inches.
Possible challenges for wheat planting and crop establishment
The current wheat-planted acreage in Kansas, according to the USDA-NASS crop progress report, was 15% as of September 22. This is very close to the 5-year average of 16%, and the crop might be favored by the forecast rain.
One challenge that early-planted fields often face is high soil temperature stress, which can lead to germination problems, especially in wheat varieties with high-temperature germination sensitivity (varieties that will not germinate when soil temperatures are greater than 85 degrees F). However, average weekly 2-inch soil temperature during September 22-28 ranged from 64 to 72 degrees F (Figure 5); thus, high temperature germination issues should not have been a problem unless earlier planted fields encountered soil temperatures above 85 degrees F. Sufficient rainfall events will continue to decrease soil temperatures and germination should occur.
Figure 5. Weekly average 2-inch soil temperature during the September 20 – 26 period. Map by Kansas Mesonet.
With about 80% of the winter wheat area still to be planted, the crop sowing progress in the following days will depend on weather conditions. While many producers might try to plant some acres before the forecast rain, a delay in planting progress can be expected after the rains, especially in central and eastern Kansas, depending on total precipitation and soil moisture conditions.
Soil conditions
If precipitation is excessive, waterlogging might occur in fields that were already planted and final stand decreased. In fields yet to be planted, producers should not hurry and sow wheat into extremely moist soils. Planting wheat under wet conditions can present either mechanical or biological challenges.
Mechanical challenges include:
- Inability to get the equipment in the field to perform plowing or sowing operations.
- Mudding up the equipment after field operations are started.
- Increased soil compaction due to machinery traffic in moist soils. Soil compaction can restrict adequate root growth, affecting plant anchorage and decreasing its ability to uptake water and nutrients.
Biological challenges include:
- Delayed crop emergence due to wet and cold soils.
- Possibly increasing early-season disease and insect problems.
Planting wheat into a dry topsoil can also be challenging. While a good seed distribution is generally achieved when sowing wheat into dry soils, if the forecast rain does not materialize, the lack of moisture for germination can result in uneven stands and high within-field stand variability (Figure 6), which can ultimately impact grain yield. Otherwise, the forecast rain will help ensure a good stand establishment.
Figure 6. Uneven wheat stands resultant from sowing into dry soils. Photo by Romulo Lollato, K-State Research and Extension.
Even in late September, we are still in the optimum wheat planting date range for most of Kansas, so producers should not hurry and sow wheat into extremely moist soils. Waiting for the water to drain and/or evaporate so the soil dries adequately before performing the sowing operation would be the best option.
Romulo Lollato, Wheat and Forages specialist
lollato@ksu.edu
Mary Knapp, Weather Data Library
mknapp@ksu.edu
Andres Patrignani, Soil Water Processes Agronomist
andrespatrignani@ksu.edu