Topdressing corn is now rarely adopted by farmers. The corn fertilization method currently used in production is the integration of sowing and fertilization, that is, applying slow-release compound fertilizer for corn into the holes at the time of sowing, eliminating the need for later topdressing. From this perspective, the topdressing strategy seems slightly conservative.

On the one hand, farmers are eager to go out to work, avoiding the long trip home to fertilize midway; on the other hand, those left behind in rural areas are mostly the elderly, weak, sick and disabled, and their physical strength is not strong enough, so the intermediate fertilization step is skipped whenever it can be. Therefore, choosing special slow-release fertilizer for corn has become the preferred option currently adopted in corn planting.

However, for those who still use midway topdressing, an introduction is given below in the hope that it can help them.

For the best choice of corn topdressing, it should naturally still be based on the fertilizer requirement pattern of corn. If the fertilizer requirement pattern of corn is not even clear, blind fertilization can hardly be called scientific fertilization.

Seedling stage

At present, corn sowing in the Huang-Huai-Hai region of China is generally after wheat stubble or garlic stubble, while in Northeast China the method is basically tillage with base fertilizer applied at sowing. For tillage and fertilization in Northeast China, a considerable amount of base fertilizer is already applied as bottom fertilizer. At the seedling stage, since the corn plants have a relatively low nutrient demand, topdressing is unnecessary, and the bottom fertilizer is fully sufficient.

The wheat stubble in the Huang-Huai-Hai region is considered the weakest in fertility, but in practice there is still no need for topdressing. After all, the nutrient demand at the seedling stage is low.

In summary, topdressing is unnecessary at the seedling stage. However, for wheat stubble, if the corn seedlings really turn yellow or show purple seedlings, topdressing can also be applied. After all, fertilization should still be chosen according to the actual situation!

Jointing stage

The jointing stage still belongs to the vegetative growth stage of corn and has a relatively high demand for nitrogen fertilizer, but in current production there always seems to be a situation of excess nutrients, so the jointing stage is also the stage for controlling excessive growth of corn! Therefore, at the jointing stage, if topdressing is considered, it should not be done blindly; fertilization must be selectively applied according to the growth conditions in the corn field.

Large trumpet stage

This period is the critical stage between the vegetative growth and reproductive growth of corn, so when considering corn fertilization, more phosphorus and potassium fertilizer should be topdressed, such as potassium dihydrogen phosphate or a combination of urea + potassium chloride (potassium sulfate), so as to meet the nutrient needs of corn.

In addition, there is the grain filling stage of corn. Although fertilization can also be considered at this stage, generally a one-time topdressing at the large trumpet stage is enough to meet the nutrient supply, avoiding multiple fertilization in the field.

Through the above analysis, Kexue Xingnong believes that in corn production, topdressing should be chosen as much as possible at the large trumpet stage. This situation is very practical whether for early spring corn in Northeast China or summer corn in the Huang-Huai-Hai region. Of course, if conditions permit, topdressing can also be chosen at the jointing stage.

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