What are the precautions for topdressing in corn fields?

1. Reasonably determine the topdressing time. If topdressing is done three times, fertilization at the seedling stage should not be done too early; 5 to 6 leaves is suitable, to help root development and produce thick, strong seedlings; the jointing fertilizer is generally suitable at 10 to 11 leaves, and mechanical operations can be appropriately advanced to avoid farm machinery damaging the seedlings; for the ear fertilizer, attention should be paid to the nitrogen application rate to prevent excessive vegetative growth; if topdressing is done only once, the jointing fertilizer should be applied.

2. Ensure deep fertilization. Corn topdressing must be applied deeply, otherwise the fertilizer use efficiency will be reduced. The most suitable depth is 5 to 10 cm, and soil should be covered promptly.

3. Topdress according to growth conditions. In fields with uneven seedlings, strong and weak seedlings should be treated differently when topdressing. Weak seedlings should be topdressed appropriately earlier, and if necessary, foliar fertilizer can be sprayed separately to promote early and rapid growth of weak seedlings; strong seedlings should be topdressed appropriately later.

4. Apply an appropriate amount of potassium fertilizer. When the amount of potassium in the base fertilizer is insufficient, an appropriate amount of potassium fertilizer can be applied together to make up for the potassium deficiency.

5. Reasonably apply foliar fertilizer. The number of sprays, spraying period and solution concentration of foliar fertilizer should be used strictly according to the product instructions. The spraying time should be before 10 a.m. or after 3 p.m., or it can be sprayed on cloudy days, avoiding operations under high temperature and direct sunlight; spray evenly on the back of the leaves, preferably so that the droplets do not drip off; if heavy rain occurs within 3 hours after spraying, it needs to be sprayed again; foliar fertilizer should as far as possible not be mixed with pesticides for spraying.

Si Zhongfeng