Considerations for corn planted under wet conditions
Recent rains have created very wet soil conditions in parts of Kansas. Some corn remains to be planted (about 38 percent as of April 30, 2017). Weekly and monthly precipitation summaries are presented in Figure 1. The forecast for the coming week is showing potential for drier conditions through about Wednesday May 10, so producers will be gearing up again to plant their remaining corn acres and begin soybean planting in eastern and central Kansas (Fig. 2).
Figure 1. Weekly (upper panel) and monthly (lower panel) precipitation summary, April 29-May 5, 2017 and April 1-30, 2017 for Kansas.
Figure 2. Weekly precipitation forecast (7-day from May 5, 2017). Upper panel, May 5-8; Middle panel, May 8-10; Lower panel, May 10-12. Source: NOAA.
What should producers expect if they plant corn into soils that are too wet, and what can they do to minimize any problems?
It is best, of course, to allow time for the soil to dry adequately before tillage or planting operations if at all possible. Wet conditions will make the soil more susceptible to compaction. Tilling some soils when they are too wet can produce large, persistent clods, complicate planting, reduce herbicide effectiveness, and destroy the seedbed. Also, compaction can occur in the seed furrow itself, restricting proper root development (also diminishing nutrient accessibility) and early plant growth.
If soils remain or become unusually wet after the corn has emerged, corn may look sickly for a while. Saturated soils inhibit root growth, leaf area expansion, and photosynthesis because of the lack of oxygen and cooler soil temperatures. Yellow leaves indicate a slowing of photosynthesis and plant growth. Leaves and sheaths may turn purple from accumulation of sugars if photosynthesis continues but growth is slowed. For further details on these points check the companion article in this issue of the eUpdate: “Effect of standing water and saturated soils on corn growth and yield.”
Figure 3. Uneven corn stand. Photo by Ignacio Ciampitti, K-State Research and Extension.
If wet weather conditions persist for more than a week, corn emergence will be delayed and seedlings will be more vulnerable to the presence of insects and diseases. Uneven corn stands likely will be greater when planting in cold and wet soils. This situation will directly affect plant-to-plant uniformity (Fig. 3), impacting potential yield.
Fortunately, the longer 8-14 day outlook is for a drier-than-normal pattern (Fig. 4), particularly in the eastern half of the state. This doesn’t exclude some rain during the period, but heavy amounts are unlikely. Also, coupled with warmer temperatures and sunshine, drier-than-normal conditions would allow for quicker drying of the soils.
Figure 4. 8-14 Day Outlook (May 12- May 18, 2017) issued May 5, 2017. Source: NOAA.
Ignacio Ciampitti, Crop Production and Cropping Systems Specialist
Mary Knapp, Weather Data Library
Doug Shoup, Southeast Area Crops and Soils Specialist
Doug Jardine, Extension Row Crops Plant Pathology
Stu Duncan, Northeast Area Crops and Soils Specialist