What are the countermeasures when corn encounters waterlogging at the seedling stage?

Although corn has a large water requirement, it is not tolerant of waterlogging. Waterlogging damage will cause corn to grow slowly, with weak plants, yellowing leaves, red stems, and blackened and rotting roots, seriously affecting corn growth and yield. So what should be done when corn encounters waterlogging at the seedling stage? What are the countermeasures?

I. Countermeasures when corn encounters waterlogging

1. Drain water and reduce waterlogging quickly

After heavy rain, according to the water accumulation situation and terrain, use drainage machinery and dig drainage ditches and other methods to drain the accumulated water in the field and the stagnant water in the plow layer as soon as possible, reduce the time of water accumulation in the field, and do a good job of dredging and clearing silt from the field ditches to ensure smooth drainage in the field ditches. At the same time, brush off or wash away the mud on the leaves and stems to restore normal leaf photosynthesis.

2. Lift lodged plants early

After a storm, lift the lodged corn as early as possible. If lodging occurs before the jointing stage, corn has a certain ability to recover upright on its own, so manual straightening is not necessary. If lodging occurs after tasseling, it must be lifted manually, but it should be done as soon as possible, preferably within 2 to 3 days.

3. Apply supplementary fertilizer in time to promote vigorous growth

After corn is waterlogged, apply a certain amount of quick-acting chemical fertilizer in time to promote the recovery of corn growth and help weak plants become strong.

4. Foliar topdressing

After the water in the field is drained, spray foliar fertilizer in time. For each mu of corn field, use 45 to 60 kg of a water solution of 0.2% to 0.3% potassium dihydrogen phosphate + 1% urea for foliar spraying, spraying once every 7 to 10 days, for 2 to 3 consecutive sprays.

5. Apply supplementary chemical fertilizer

After the root absorption function of the plants recovers, apply fertilizer at the roots to supplement soil nutrients. For plots where corn is at or before the tasseling and flowering stage, apply 20 to 25 kg of high-concentration compound fertilizer per mu, and at the large trumpet stage or tasseling and flowering stage apply 7.5 to 10 kg of urea per mu to promote the recovery and vigor of corn.

6. Strengthen pest and disease control

After the disaster, because field humidity is high, pests and diseases often occur and spread. Therefore, for affected plots, focus on controlling pests such as corn borers and corn leaf blight in the middle and late stages.

II. Measures to prevent corn waterlogging damage

1. Choose waterlogging-resistant varieties

Waterlogging-resistant varieties generally have relatively well-developed air cavities in the root system, and under waterlogging-prone conditions their leaf color is better and there are fewer withered and yellow leaves. In waterlogging-prone areas, among existing corn hybrids, choose varieties that are relatively resistant to waterlogging.

2. Site selection

In waterlogging-prone areas, try to choose plots with high terrain for planting, and it is not suitable to plant in plots with low-lying terrain, heavy clay soil, and a relatively high groundwater level.

3. Ridge platform cultivation

In low-lying, waterlogging-prone areas, dig ditches and form ridges in the farmland, and plant corn on the ridge platforms. Because aeration conditions are good, this can reduce waterlogging damage and turn harm into benefit.

4. Adjust sowing date

Corn is most afraid of waterlogging at the seedling stage, and after jointing its waterlogging resistance gradually increases. Therefore, the sowing date can be adjusted so that the growth stage most afraid of waterlogging is staggered from the rainy and waterlogging-prone season. In North China, the rainy season often begins in late June or early July. By using interplanting in wheat rows and sowing early after wheat harvest, try to make corn joint before the rainy season begins, improving its stress resistance.

5. Drainage

A three-level drainage system can be established, connecting the furrows between corn rows, the main drainage canals perpendicular to the rows, and field drainage ditches parallel to the rows about every 25 m apart into one integrated system, with the ditch depth increasing level by level, so that field water can be drained quickly. In the south, bed cultivation is used for drainage. In plots with high terrain and good drainage, use wide beds with shallow ditches; in low-lying land, use narrow beds with deep ditches. The bed ditches should be straight, and the drainage ditches should be unobstructed, so that water flows away as rain comes and drains away when rain stops.

6. Intertillage

When it is possible to enter the field, carry out intertillage and loosening of the soil in time to promote the recovery of corn growth.

7. Apply more quick-acting nitrogen fertilizer

Waterlogged corn often shows yellow leaves and red stalks and is slow to resume growth. Applying more quick-acting nitrogen fertilizer can change the plant's nitrogen nutrition, restore its growth, and reduce waterlogging losses.

8. Control pests and diseases

After waterlogging disasters, pests and diseases often worsen, especially in the Yellow River, Huai River, and Hai River regions, where control should focus on corn borers. Do a good job of pest and disease forecasting and carry out timely control.

9. Promote early maturity

After waterlogging occurs, the corn growth period is often delayed and may be threatened by low-temperature chilling injury. Measures to promote early maturity can be taken, such as detasseling alternate rows or alternate plants, removing lower leaves, root cutting, and peeling open the husks after the milk stage, to promote grain filling and maturity. Spraying chemical ripening agents on corn leaves can also have the same effect.

10. Autumn sowing of corn

In southern regions, if waterlogging damage is relatively severe, autumn sowing of corn can be used as a disaster-resistant measure. Early-maturing corn hybrids should be selected, sowing should be completed before the end of August, density should be increased, quick-acting fertilizer should be applied, and pests and diseases should be controlled to strive for a better harvest.