The strategy of feeding corn

The «corn boom» on the queen of fields, which has been observed in recent years, makes farmers think about how to increase its productivity? It is clear that water, solar insolation, optimal temperature conditions, CO₂, O₂, high-quality seeds play a key role in production processes, but a properly selected strategy for the corn fertilization system is not the last violin in this orchestra, but we can say the main lever that ensures normal growth and development, as well as determines future yields.

Corn requires significantly higher rates of fertilizers than other cereals. According to the amount of nutrients that are used to form the crop, corn is equal to sugar beet and potatoes. Areas with the most fertile soils and the best precursors are allocated for corn crops. Corn forms high yields on soils rich in nitrogen, with good physical properties, loose, well permeable to water and air. It grows well on light soils fertilized with manure or green fertilizer, worse - on saline, heavy and those that are very swam. For the formation of 1 ton of grain, modern corn hybrids take out such an amount of nutrients from the soil: 24-32 kg of nitrogen, 10-14 kg of phosphorus, 25-35 kg of potassium, 6-10 kg of magnesium and calcium, 3-4 kg of sulfur, 11 g of boron, 14 g of copper, 110 g of manganese, 0.9 g of molybdenum, 85 g of zinc, 200 g of iron. The level of application of mineral fertilizers is calculated based on the planned harvest, depending on the predecessor and on the level of mobile forms of nutrients (nitrogen, phosphorus, potassium), mg / 100 g in the soil.

Approximate application rates in kilograms of mineral fertilizers for corn for the planned harvest.

NPK	productivity
	40 c/ha	60 c/ha	80 c/ha	100 c/ha
nitrogen (N)	100 – 130	130 - 180	160 – 240	200 - 300
phosphorus (P)	30 - 80	40 - 110	50 - 130	60 - 150
potassium (K)	100 - 140	150 - 190	200 - 250	250 - 310
calcium (Ca)	24 - 40	36 - 60	48 - 80	60 - 100
magnesium (Mg)	24 - 40	36 - 60	48 - 80	60 - 100

In the development of corn, two important periods of nutrition with the main elements can be distinguished: the period of formation of 5-7 leaves and the period from the appearance of 9-10 leaves to the complete release of the panicle.

In the first period of corn development, the reproductive organs are laid. The number of cobs on the plant and the grains on them depends on the presence of nutrients, especially phosphorus. During this period, corn grows poorly, uses few batteries. Its root system is still poorly developed and cannot absorb nutrients from hard-to-reach compounds. Therefore, corn at this time is very demanding on the presence of easily digestible nutrients in the soil, especially phosphorus. 10-15 days after the appearance of corn seedlings, a critical period in the phosphorus nutrition begins. Phosphorus contributes to the good development of the root system, enhances the use of nutrients from the soil and fertilizers by the plant, accelerates the laying of reproductive organs. This feature determines the high efficiency of applying phosphorus fertilizers during sowing.

Corn is a very demanding crop in terms of nutrition. It gives a high yield only where the soil is rich in nitrogen and other necessary elements. A caring owner necessarily makes a pre-sowing filling of the soil with organic matter and mineral fertilizers. So why do we need to feed corn? Isn't it easier to immediately add the necessary amount of nutrients to the soil?

Why do we need top dressing?

Firstly, this plant reacts very poorly to an increase in the concentration of soil solution. Too much minerals for her can be a more serious problem than their lack. For example, with an excessive content of phosphorus introduced in the pre-sowing period, the seeds may simply not rise, or they will do it for a very long time and not exactly.

Secondly, unlike most other crops, corn increases its green mass during the entire growing season. Because of this, fertilizers are required for her from spring to autumn. Moreover, in different periods of life, plants need the presence of different nutrients. So, nitrogen is absorbed most of all before the formation of panicles, and potassium-during the initial period of vegetation.

Additional nutrition during the whole season is especially important on light and sandy soils. Fertilizers applied before sowing are quickly washed out of them by rains. The nutrients dissolved by water simply leak out or end up in the lower, hard-to-reach layers for the roots.

What does corn need?

Nitrogen is required for corn almost until the end of seed maturation. But the plant absorbs the maximum amount of it in the period preceding the formation of inflorescences. Nitrogen fertilization is usually needed on sod-podzolic and forest gray soils, as well as on leached chernozems. But we must remember that it only enhances the effect of basic fertilizers, and does not replace them. Additional nitrogen is especially necessary if it was not introduced in previous years and during the pre-sowing preparation of the soil.

Potassium is most intensively absorbed in the first half of the growing season. And in the second, there may even be an outflow of this element from the plant back into the soil. Potash fertilizing is most often required on sandy loam, floodplain and peat soils. And, of course, if corn is sown after its predecessors, who mainly needed potassium nutrition – potatoes, root crops.

Phosphorus is necessary for corn throughout the season, but in slightly smaller quantities. The plant absorbs it evenly until the grain ripens. But a special need for additional phosphorus arises at the very beginning of development. Therefore, it is recommended to use it first of all before sowing – in the main filling. It is then that it promotes the development of roots, early flowering and rapid ripening of grain.

But in addition to the basic substances, corn necessarily needs trace elements. Especially, zinc and manganese are needed, a little less – copper and boron. The deficiency of these substances may occur due to the poverty of the soil or any of its special properties, for example, low acidity.

On alkaline soils, boron and manganese are often not enough. On acidic-calcium. In the initial period of development, when the roots are still too weak, corn often suffers from a lack of zinc. These trace elements contribute to the strengthening of enzymatic activity, and therefore are especially important for the plant during intensive growth.

When and how to feed corn?

It is believed that top dressing gives the greatest effect if it is produced in two terms. The first one coincides with the period of appearance of the third and fourth real sheets.

The second feeding is done just before the appearance of panicles.

In addition to these two, sometimes you have to do additional, unplanned fertilizing. This happens when a shortage of any specific elements is detected. For example, the lack of zinc is signaled by light stripes appearing on corn leaves. When fertilization is delayed, there is most often a lack of boron, which is necessary for the growth of the pollen tube.

It is recommended to fertilize corn with special cultivators-plant feeders, capable of evenly distributing fertilizers to the optimal depth in moist soil. But in some cases, it is the foliar application of fertilizer solutions with the help of sprayers that is effective. So, recently, positive results have been obtained with foliar fertilization with a urea solution two to three weeks before the formation of panicles. This procedure significantly increases the protein content in the stems and leaves of the plant. Urea is the best nitrogen fertilizer for foliar fertilization, since (with proper application) amide nitrogen is absorbed by 90-95% of the leaf surface of plants, and (importantly) in a very short period of time.

It is recommended to combine leaf dressing with urea in one working solution with pesticides and micro-fertilizers, which improves the effect of chemicals and reduces the influence of stress factors caused by them. Top dressing with a solution of urea is recommended to be carried out at an air temperature of not more than + 20 ° C and not less than + 10 ... 12 ° C, in the evening or (in cloudy weather) in the afternoon, which provides an increase in the nitrogen utilization rate from the fertilizer. Leaf feeding is especially effective on healthy plants that are well provided with other nutrients.

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