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 50 percent as of April 25, 2016). Weekly and two-week precipitation summaries are presented in Figure 1. The forecast the coming week is also showing potential chances of rain across the state, presenting a challenge for planting the remaining corn acres and for starting soybean planting in eastern and central Kansas (Fig. 2).
Figure 1. Weekly (upper panel) and two-week (lower panel) precipitation summary, April 15-28, 2016 for Kansas.
Figure 2. Weekly precipitation forecast (7-day from April 27, 2016). 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 6-10 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. 6-10 Day Outlook (May 4- May 8, 2016) issued April 28, 2016. Source: NOAA.
Ignacio Ciampitti, Crop Production and Cropping Systems Specialist
Mary Knapp, Weather Data Library