Effect of water-logged soils on corn growth, yield
click image to zoomIgnacio Ciampitti, K-State Research and ExtensionFigure 1. Corn under water June 11, 2014 at K-State's Ashland Bottoms experiment field near Manhattan. Heavy rains in some parts of Kansas over the past week or two have subjected some fields of corn to saturated soils or even flooding for a day or two, or even more. Producers should know what might happen to their corn as a result of early-season wet conditions so they can correctly diagnose any future problems that may occur as the season progresses.
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.
Corn plants can recover with minimal impact on yield if the plants stay alive and conditions return to normal fairly quickly. Although root growth can compensate to some extent later in the season, a saturated profile early in the season can confine the root system to the top several inches of soil, setting up problems later in the season if the root system remains shallow. Corn plants in this situation tend to be prone to late-season root rot if wetness continues throughout the summer, and stalk rots if the plants undergo mid- to late-season drought stress. Plants with shallow root systems also become more susceptible to standability problems during periods of high winds. Overall, shallow root systems are more prone to drought and nutrient stresses, due to the diminished capacity of the plant to explore the entire soil profile.
click image to zoomIgnacio Ciampitti, K-State Research and ExtensionFigure 2. Flooded corn at Ashland Bottoms near Manhattan, June 11, 2014. Young corn plants typically can tolerate full submersion for up to 48 hours with minimal impact on yield. If flooding occurs before V6, when the growing point is at or below the soil surface, flooding that lasts more than 2 to 4 days can impact season-long plant growth and grain yield or cause significant plant mortality. Chances of plant survival increase dramatically if the growing point was not completely submerged or if it was submerged for less than 48 hours. Research has demonstrated yield reductions from early-season flooding ranging from 5 to 32 percent, depending on soil nitrogen status and duration of flooding.
Temperatures can influence the extent of damage from flooding or saturated soils. Cool, cloudy weather limits damage from flooding because growth is slowed and because cool water contains more oxygen than does warm water. Warm temperatures, on the other hand, can increase the chances of long-term damage.