Corn Management in Flooded Fields

KEY POINTS

  • Heavy spring rains soon after planting or emergence may reduce yield potential.
  • Flooded/saturated soils may contribute to reduced plant population, increased nitrogen (N) loss, and soil crusting problems.
  • Fields should be evaluated to determine if replanting is warranted, additional N is needed, and if other management tasks would be beneficial.
  • Replanting decisions should be based on comparing yield potential of the original planting date and reduced plant population versus a later planting date, expected replant population, and replanting costs.

Topic

The effect of flooding on yield potential is influenced by the corn growth stage when the flooding event occurs, length of time corn plants are submerged, and temperature. Corn plants need oxygen to survive, and oxygen is depleted in the soil after about 48 hours.1,2 Corn plants at or below the soil surface are at the highest risk of dying when a field is flooded; however, submerged plants can survive for 2 to 4 days.2 Emerged corn and plants with a growing point above water have a better chance of survival. Temperature is one of the most critical components of plant survival while the field is flooded. If temperatures are above 77 °F, the plant may not survive 24 hours under water.2 If temperatures are cooler (<77 °F), corn with fewer than six leaves can survive approximately four days of flooding.1

 

Figure 1. Some corn younger than the 6-leaf growth stage can survive 4 days of flooding.1

Effect

Significant loss of pre-plant nitrogen (N) through denitrification or leaching can occur in corn fields submerged for more than two days. Saturated soils result in denitrification, which tends to be more prevalent in heavier-textured soils, whereas leaching is more prevalent in sandy soils.

Soil moisture can increase N losses due to denitrification. Research conducted in Nebraska indicated approximately a 10 to 25 percent nitrate loss when soil is saturated for 5 and 10 days, respectively.3 This was reported while soil temperatures were between 55 and 60 °F. Sidedressing more N is a possible solution if considerable N was lost in the field.

As wet soils dry, the soil surface can form a crust causing seedling emergence to be inhibited. A rotary hoe can break up the crust and aid seedling emergence. Timing is essential, and breaking the crust as soon as possible is most beneficial.

Action

It is important to scout corn fields three to five days after the water has receded.1,2 Dig up seedlings and inspect the growing point. A white or cream-colored growing point that is still firm indicates the plant is recovering. Dark and soft growing points usually precede plant death.2 Stand counts of healthy plants should be taken to determine if a desirable plant stand survived. Replant decisions should be based on comparing yield potential of the original planting date and reduced plant population versus a later planting date, expected replant population, and replanting costs. Regional data concerning expected yield potential based on planting date and plant population may be obtained from your local Extension Service.

If replanting with corn, minimum or no tillage is recommended to maintain efficacy of any herbicides and/or soil insecticides already applied to the field. If herbicides had been applied prior to the flooding event and you are considering replanting with soybeans or other crops, check the herbicide product label to determine if the previously applied corn herbicides could damage the replanted crop. It is important to scout fields entirely before making the decision to replant.

Sources:1 Elmore, R., Daugherty, R.B., and Mueller, N. 2015. Corn and soybean survival in saturated and flooded soils. University of Nebraska-Lincoln. https://cropwatch.unl.edu/corn-and-soybean-survival-saturated-and-flooded-soils. 2 Thomison, P. 2005. Ponding effects on corn. Corn Newsletter. Ohio State University Extension. https://agcrops.osu.edu/newsletters/2006/13. 3 Ferguson, R.B. 2008. Assessing nitrogen loss due to saturated soils. University of Nebraska-Lincoln. https://cropwatch.unl.edu/assessing-nitrogen-loss-due-saturated-soils. 4 Al Kaisi, M. and Pedersen, P. 2007. Wet conditions: challenges and opportunities. Iowa State University Extension. Integrated Crop Management. ICM>2007>IC-498(9). https://crops.extension.iastate.edu/wet-conditions-challenges-and-opportunities. Web sources verified 1/19/18


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