Primary symptoms
Pale green upper leaves and the bronze color of the lower leaves, which are senescing prematurely.
Confirm waterlogging by checking the additional evidence required.
Summary
The maize crop is quite sensitive to waterlogging, that is, to saturated soils. From planting to the V6 stage, waterlogging for more than 24 hours can kill the crop (especially if temperatures are high) because the growing point is below the soil surface at that time. Later in the crop cycle, waterlogging can be tolerated for periods of up to one week, but yield will be reduced significantly.
| Causes of waterlogging | Additional evidence required |
|---|---|
| Field is not level. | Look over the field for low spots. |
| Drainage is poor due to a hardpan. | Measure soil depth in the affected areas. |
| Very heavy rains or excess irrigation. | Check the amount of water received. |
| Inappropriate use of tied ridges or contours. | Examine land preparation methods. |
Is waterlogging a problem?
Evidence: observations.
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If there has been rain recently: Is there water standing in the field for more than 12 hours after a rain? Examine the soil surface in areas where crop growth is poor. Is the soil very wet, perhaps with algae growing on the surface? Are the plants wilted at midday even though the soil is quite wet? These symptoms indicate waterlogging.
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If you visit the field during a dry period, look for a thin crust of silt on the surface in areas of poor crop growth.
Examine the plants. Are there patches of plants which appear nitrogen deficient? Look closely at the lower leaves of the plants in these patches. Waterlogging causes lower leaf senescence, and the dead leaves often have a bronze color. Is weed growth in these patches less, or are the species of weeds different than in the rest of the field? The economic importance of waterlogging will be related to the size of the affected areas and the reduction of yield in those areas.
Possible solutions
- Level the field, or avoid planting maize in the low areas.
- Break up the hardpan by subsoiling or by planting a deep-rooted crop for a cycle.
- Install drainage canals.
- Plant on wide raised beds or on ridges.
- Improve weed control.
- Reduce the density of the intercrop, or plant the intercrop later in the growing cycle.