Corn is one of the important food crops in China, and corn topdressing is a supplement to the corn growth and development needs to meet the needs of corn growth and development, and it is a necessary guarantee to achieve high quality and high yield of corn. The following small series gives you a brief talk about the corn topdressing things.

1. Fertilizer law

The absorption of nitrogen by corn is relatively stable. The peak of the silking reaches the peak, the absorption speed of the filling stage is slowed down, and the nitrogen fertilizer is absorbed throughout the growth period.

During the whole growth period of corn, the phosphate fertilizer is absorbed, which is also the peak in the most vigorous flowering and flowering period, and the phosphorus absorption in the later stage is decreased, but it still accounts for about 1/3.

The absorption of potassium by corn is the highest from jointing to booting, and the flowering period is the highest, and then the absorption of potassium is stopped. Since then, potassium has decreased in the plant due to potassium extravasation.

2. Deficiency symptoms

In addition to absorbing a large amount of nitrogen, phosphorus and potassium, the whole corn growth period requires a small amount of trace elements such as zinc, molybdenum and copper. The common deficiency syndromes are:

Nitrogen deficiency: The leaves turn yellow, the plants are short, and the tips of the lower leaves turn yellow.

Phosphorus deficiency: all the leaves are yellow, brown spots appear, and the edges of the leaves and the tips of the leaves are dry and burnt.

Zinc deficiency: The leaves appear white seedlings, and the symptoms usually appear in the middle of June, 7-9 leaves.

Potassium deficiency: Because potassium is easy to move and reuse, the deficiency first occurs on the old leaves. The central part of the new leaves and the old leaves are dark green, the tip and edge of the leaves are yellow and necrotic, and the boundary with the healthy part is obvious. The blade folds and bends. At the same time, only roots are formed near the main root, and lateral pole growth is limited.

3. Time, quantity and method of top dressing

Mastering the time, method, quantity of topdressing and the type of fertilizer applied according to the deficiency are several major factors affecting corn yield. Therefore, in order to increase the yield of corn and achieve high yield and quality, it is very important to master the best time for top dressing, the amount of fertilizer and the type of fertilizer applied.

Topdressing time: Topdressing should be carried out around 10 leaves of corn, which can promote spikelet differentiation. It is best to chase after 2 times. If time is tight, you can also apply top dressing in the first half of July.

The number of top dressing: the period, number and quantity should be determined according to the law of corn absorption, the level of yield, the basis of soil fertility, the amount of fertilizer applied, the application of base fertilizer and seed fertilizer. High-yielding fields, good foundations, and a large number of top-dressing fertilizers should be applied with light-seeking seedlings, heavy-chasing ear-fertilizers, and top-dressing fertilizers. The amount of seedlings is about 30% of total nitrogen and 50% of ear fertilizer. Granular fertilizer accounts for about 20%; medium-yield fields, good soil fertility foundation, and high amount of topdressing should adopt the secondary topdressing method of applying sufficient seedling fertilizer and heavy-seeking fertilizer, with about 70% of seedling fertilizer and 30% of ear fertilizer; The method of using low-yield seedlings and light-seeking fertilizers with low-yield fields, poor foundations and low top-dressing fertilizers has a good effect. The seedling fertilizer accounts for about 60%, and the ear fertilizer accounts for about 40%.

Master the best time for topdressing, realize scientific fertilization and economic fertilization, and lay a solid foundation for increasing corn production and income.

Miao fertilizer: Generally, it is applied after the seedling is fixed to the jointing stage (about 30% of the leaf age index). The imminently introduced seedling fertilizer and jointing fertilizer are combined for one application, which has the functions of promoting roots, strong seedlings and promoting leaves and strong stalks, laying a good foundation for the ear and the ear. In addition to the application of quick-acting nitrogen fertilizer, the seedling fertilizer can also be applied with phosphate fertilizer and potassium fertilizer at the same time, or can also be applied with decomposed organic fertilizer.

Jointing fertilizer: jointing fertilizer can promote the increase of middle and upper leaves, increase the photosynthetic area, prolong the photosynthesis of the lower leaves, and lay a good foundation for promoting roots, strong stalks and increasing ears. The top-loading fertilizer is mainly nitrogen fertilizer. It can be applied 10-15kg urea ditch or hole every 667m2 to avoid the application before heavy rain to prevent it from being leached by rain. For the fields with insufficient phosphorus and potassium fertilizer in the soil, the three-element compound fertilizer can also be blended with 7.5-10kg/mu.

Spike fertilizer: Corn is applied to panicle fertilizer during the big bell stage, which can meet the nutrient requirements of panicle differentiation, increase the photosynthetic productivity of the middle and upper leaves, increase the nutrient input to the ear, and apply the quick-acting nitrogen fertilizer to the panicle fertilizer. It is advisable to apply 15-20kg of urea per 667m2.

Granular fertilizer: refers to the fertilizer applied after corn tassels are generally applied in the filling stage. After the corn is taken from the male to the mature stage, the nutrients of about 40% of the total nitrogen and phosphorus are absorbed from the soil. At the same time, about 80% of the grain yield is the photosynthetic yield produced by the later leaves. Therefore, in the later stage, a certain amount of quick-acting fertilizer should be applied to ensure the adequate supply of inorganic nutrients, extend the functional period of the leaves, increase the photosynthetic efficiency, increase the accumulation of photosynthetic products, and promote the grain and grain weight, so as to achieve high quality and high yield.