Some areas of central and eastern Nebraska received extensive precipitation over several relatively short periods this week, causing flooding in rural and urban areas. How much rain is too much and how long is too long when fields are flooded? The severity of damage from flooding and ponding will depend on the depth of the flooding, the length of time an area was flooded and the temperature of the flood water. Depth of flooding refers not only to the water visible above ground, but also to the level of moisture in the soil profile. In some situations, producers may want to dig ditches to help drain a field more quickly. Before doing so, check with the Natural Resource Conservation Service (NRCS) to ensure that you will not be committing a wetlands violation. Help facilitate field drainage by ensuring that drainage paths are clear of plant residue, brush and other clogging materials. Even after the surface flood water has receded, the soil may remain saturated for some time. While the shoot may appear healthy, the roots may be suffocating. Once the surface water has receded, the field's ability to drain internally will be important. Tiled fields will drain faster, providing quicker relief to the crop.
Understanding Types of Field FloodingField flooding may occur by either stream flooding or lowland flooding. The former results from creeks or rivers overflowing their banks onto a flood plain. In this case silt and sand is often deposited in the field and plant tissues are covered with soil material. The latter case results from water accumulation in depressed areas due to inadequate soil permeability or surface drainage.These flooding types can be further divided into soil waterlogging, where the soil is merely saturated, or complete submergence where the crop is entirely submerged. The type of flooding occurring on a farm directly impacts growth and yield potential of [soybeans in] that field. Although stream flooding can quickly recede, the resulting silt deposits can bury the crop and cover leaf tissue with thick layers of soil. Without rains to wash silt from soybean leaves, recovery is greatly slowed. Fortunately, soil types prone to stream flooding are often coarse-textured. These sandy soils drain well, allowing quick crop recovery or replanting. Lowland soils often retain water so that as the water disappears from the surface, the soil profile may remain waterlogged for several more days.
Seth Naeve |
Early spring flooding is a lot less harmful than late spring flooding when the flood waters are apt to be warm. The temperature of the flood water is important for two reasons:
Seth Naeve, Extension Soybean Specialist at the University of Minnesota, notes several indirect effects of flooding on soybeans, which producers also may need to be addressed. They include 1) root diseases, 2) nitrogen deficiency, 3) and other plant nutrient imbalances. Caring for recuperating soybean stands should focus on reducing further plant stress where possible.
Cultivation should be considered to increase soil aeration, and post- emergence herbicides should only be applied to conventional soybean crops judiciously. Herbicide stress should be minimized and postponed where possible, Naeve writes in his University of Minnesota publication, Flooded Fields and Soybean Survival, MNCN80, published June 14, 2002.
Producers may want to carefully weigh the costs and benefits of further inputs into some badly damaged fields. To confirm plant survival, check the color of the growing point. It should be white and cream colored rather than dark and soft. New leaf growth should appear three to five days after water drains from the field.
Replanting may not be a very viable option in many fields where conditions are likely to stay soggy for several weeks, not allowing for timely field work and planting.
Soybean producers with field populations below 75,000 plants per acre may consider replanting if they can get back into the field relatively soon. Lenis Nelson, Extension Crops Specialist, did not recommend changing the maturity class significantly when replanting soybeans. If a producer had previously planted a mid-group II variety, he or she might consider now planting an early group II variety.
Nelson also recommended planting in narrow rows so the canopy closes faster and weeds are better controlled.
Bob Caldwell
Extension Cropping Systems Specialist
Lisa Jasa
Crop Watch Editor
| CropWatch |
| CW Archives |
|
 | ||
| Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture. | ||
| The University of Nebraska-Lincoln does not discriminate on the basis of gender, age, disability, race, color, religion, marital status, veteran's status, national or ethnic origin, or sexual orientation. | ||