Summer brings frequent heavy rainfall, and waterlogging in fields easily leads to crop damage. Flooding not only causes significant leaching of soil nutrients and root suffocation due to oxygen deprivation, but also induces outbreaks of pests and diseases due to persistent high humidity. Improper handling can result in substantial yield reduction or even total crop failure. Post-disaster management should follow the principle of "first save lives, then rejuvenate, and finally protect yields," implementing step-by-step scientific rescue measures to minimize disaster losses.
Draining accumulated water is the primary task after a disaster. For dryland crops, efforts should be made to drain all surface water from the fields within 24 hours, and no later than 72 hours. For dryland crops, ditches, side ditches, and perimeter ditches should be cleared promptly. In low-lying areas, cross-shaped drainage ditches should be dug. If the water is too deep, pumps should be used for forced drainage, prioritizing the removal of water from the crop root zone. Extra care is needed for paddy fields. During hot, sunny days, it is strictly forbidden to drain the field all at once. Drainage should be done in stages, maintaining a shallow water layer of 3-5 cm to prevent excessive transpiration from leaves, which can cause seedlings to wither and die. For greenhouse crops, the power supply must be disconnected first to eliminate the risk of electrical leakage before drainage operations can begin.
After the water recedes, it is necessary to restore the plants' photosynthetic capacity and improve soil aeration as quickly as possible. Rinse the stems and leaves with clean water to remove mud, rotten branches, diseased plant parts, and debris from the field and dispose of them properly to reduce sources of pathogens. Lightly lodged crops do not need forced straightening; they can recover naturally relying on plant geotropism. Severely lodged crops may be gently straightened and fixed by hilling up soil once the ground dries out. Once the soil surface has dried to the point where it is no longer sticky to the touch, perform shallow cultivation to a depth of 5-10 cm to break up soil compaction. Deep tilling is strictly prohibited to avoid damaging the roots.
Fertilization should follow the principle of "foliar application first, then root application, and frequent application of diluted fertilizer." After flooding, root systems have weakened absorption capacity, so it's crucial not to immediately apply large amounts of root fertilizer. Instead, first spray the entire field with a mixture of 0.2% potassium dihydrogen phosphate + 0.15% urea + brassinolide, repeating once every 7 days for 2-3 applications. This will quickly replenish nutrients, enhance resilience, and promote new root growth. Once the plants have recovered, apply an appropriate amount of fast-acting nitrogen and potassium fertilizer, along with bio-fertilizer to improve the rhizosphere environment.
Flooding is often followed by outbreaks of pests and diseases, known as "secondary disasters," requiring preventative measures. High humidity creates a breeding ground for pathogens, making field cleanup urgent. Diseased plants, damaged leaves, and rotten fruit should be removed from the field and destroyed to reduce sources of infection. After the rain stops and the weather clears, once the leaf surface is slightly dry, immediately spray with a broad-spectrum fungicide for prevention. Specific prevention and control measures vary depending on the crop: rice should be protected against sheath blight and rice blast, vegetables should focus on preventing blight and soft rot, and corn should pay attention to large leaf spot and stem rot.
