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Late-Season Flooding Effects On Corn

Torrential rain fell across areas of central and eastern Nebraska this week, causing creeks and fields to flood. With more rains predicted for Sunday, how may flooding affect corn productivity?

The USDA National Agricultural Statistics Service reported that as of Sunday, 89% of Nebraska's corn was in the dough stage (R4) and 44% had dented (R5). Approximately 95% of soybeans were setting pods (R3 to R4). Gary Zoubek, Extension Educator in York County, indicated that soybeans planted at the normal time were at the full pod fill stage (R6).

The impact on corn of late-season flooding is highly dependent on :

  • Stage of development. Dry matter production increases dramatically during the dent stage of development. At beginning dent more than half of a kernel's weight is water; that means more than half of its dry matter remains to be accumulated. See Table 1.
  • Length of the flooding period. Peter Thomison, Ohio State University, states, "Research indicates that the oxygen concentration approaches zero after 24 hours in a flooded soil. Without oxygen, the plant cannot perform critical life-sustaining functions, such as nutrient and water uptake is impaired, root growth is inhibited, etc. Even if flooding doesn't kill plants outright it may have a long-term negative impact on crop performance." The longer the period of submersion, the more chance of yield losses. Plants under water and roots in saturated soils are limited in their ability to function.
  • How much of the corn plant was immersed during flooding. If the ears were not covered with flood water, expect less yield loss. However, if the ears were covered, expect greater loss.
  • If water drains rapidly and dry, warm conditions prevail, problems associated with flooding may be reduced.

Flooding will affect both grain and silage quality. Stalk and ear rots may be extensive and kernel sprouting on the ear may occur. Roots can die prematurely and when combined with weakened stalks, there is a greater chance for stalk lodging.

Bob Nielsen, Purdue University extension agronomist, writes "Crops inundated by standing water [in August] typically do not survive as long as those similarly affected earlier in the season due to the warmer air and soil temperatures. Oxygen deprivation in saturated soils quickly causes significant deterioration and death of above- and below-ground plant tissue. Affected crops may only survive a few days with typical August temperatures."

In addition, Nielsen reminds us that flooded soils may lose nitrate nitrogen through denitrification and/or leaching.

Source : unl.edu


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