All about plant fertilization

How and when to fertilize sweet corn


Sweet corn is a plant in the herbaceous family that grew out of mutations in common corn. The main origin comes from America, although the mutations that brought the sweet version occurred many years later. Currently it is widely used to prepare hundreds of meals, being cultivated in all parts of the world. Given this popularity, it was not possible to miss an article on our website about the fertilizer for sweet corn, we will discuss how and when we should apply it, in what amounts and what type of fertilizer to use.

Note: This type of crops is very common to plant both in large areas and in small orchards. This can bring different treatments for each type of crop, knowing this in the section how and when to fertilize you will find the analysis discriminated between large and small crops.

1. NPK values – ​​What is its meaning?


If you ever had to go buy a fertilizer in a nursery and you don’t have much experience, you may have been confused when choosing between one package or another. Perhaps the only notable variation that existed between one package and another was three numbers separated by a hyphen.

If you didn’t ask the seller what exactly those three numbers are, you may still have doubts. Well it’s your lucky day, here we will answer that question.

The three numbers in a fertilizer package are what are known as NPK values, and each letter represents one of the three most important micronutrients for plant development.

fertilizer for sweet corn
Sweet corn
  • N: represents nitrogen, which is the most important nutrient for leaf development, and is also the main chemical involved in photosynthesis.
  • P: represents phosphorus, being responsible for the development of roots, stems, flowers and fruits in a more vigorous plant.
  • K: this last letter represents potassium, nutrient responsible for giving more strength to the plant. Contributing to a better initial growth, giving greater resistance to diseases, reducing possible stress and improving the quality of the fruits.

So these NPK numbers represent the percentage of the total of each nutrient. Explaining in one example, in a 1 kg fertilizer package of a 10-5-15 mix, 10% is nitrogen (i.e. 100 g of the total), 5% is occupied by phosphorus (50 g) and the 15% potassium (150 g)

As you may have noticed, it is a fairly simple concept. With this already learned, we can continue with our article on sweet corn.

2. How to grow sweet corn?


Although fertilization is an important point when it comes to growing sweet corn, it is by no means the only care you need to take to have a good harvest. Let’s see the most important:

  • Climate: This is a very sensitive plant when it is cold. The temperature range that can be considered optimal for its development is between 25 and 30 ° C. Also, soil temperatures below 10 ° C will prevent the seed from germinating.
  • Location: An essential detail when looking for a place to plant is to keep in mind that it must be isolated from any common corn crop. This is because if they coincide in the flowering season, there may be cross-pollination hybridization. A distance between 250 and 500m may be adequate.
  • Soil: Sweet corn adapts to many types of soil, preferring those with good drainage. Also another important aspect is that the pH is between 5.5 and 7.
  • Sowing: as we have already said, the soil temperature is important and must be above 10 ° C. At the time of sowing, the seeds must be placed at a depth not greater than 2.5 cm. With a row spacing of approximately 0.75 m and a separation between each grain of 0.20 cm.
  • Irrigation: This is a crop that needs large amounts of water. It is important that during its development it does not suffer from a lack of water if what is sought is an optimal harvest.
  • Pests: There are many pests that can attack you. Among the most common are soil worms, drills, aphids, etc. A regular control of the crop helps to prevent attacks, being able to take measures in time.
  • Fertilization: Although we will develop this aspect in depth in the following sections, I can tell you that it requires a lot of nitrogen and a little less potassium and phosphorous.

If you are reading this post, you will probably be interested in learning about fertilizing these other plants.

3. Best fertilizer for sweet corn


To start talking about the best fertilizer options you can apply to your sweet corn crop, it’s important to differentiate between organic and inorganic.

Although the most recommended is to make a combined use between organic and inorganic fertilizers, it will be up to the farmer to decide. Regardless of the type used, it is important to control the doses. Keep in mind that it is generally easier to solve a problem of lack of fertilizers than an excess.

3.1 Inorganic fertilizer

Among the inorganic fertilizers that can be used, the most common are those with a balance between the three nutrients. Since we discussed the meaning of NPK values at the beginning of the post, you can imagine that a balanced fertilizer is one with its three equal numbers.

Mixtures 15-15-15 or 10-10-10 are widely used. Although on many occasions, and especially when applied together with organic fertilizers, other options are chosen, such as 12-12-17 or 16-16-8.

Since the nitrogen needs of this corn are important, it is very common to fertilize with urea. Although considered by some to be an inorganic fertilizer, it is actually a chemical fertilizer of organic origin.

3.2 Organic fertilizer

There are many options when it comes to selecting an organic fertilizer for your sweet corn. The important thing before applying it is knowing what nutrients and in what amounts each contributes.

That is the advantage that inorganic fertilizers have over organic ones. Since controlling the proportions of each nutrient is much easier.

To give you an idea, we will list some of the most common organic fertilizers and their compositions:

  • Compost: it is one of the most variable organic fertilizers in terms of composition. Although it can be assured that it is a source that will provide the three nutrients, defining the amounts of each one is very difficult without carrying out an analysis.
  • Manure: without a doubt this together with the compost is one of the most popular. Depending on the origin of the manure, its composition will vary. For example, in horses the composition is generally Nitrogen 0.70%, phosphorus 0.25% and potassium 0.55%. While that of the cow Nitrogen 0.6%, phosphorus 0.15% and potassium 0.55%.
  • Blood flour: dried blood converted to powder is a great contributor of nitrogen (12%), in the same way that it also contributes some phosphorus (0.4%) and potassium (0.3%).
  • Wood Ash: This is a fairly alkaline material (ph emtre 9-13). Giving in terms of nutrients 1% phosphorus and 4% potassium.
  • Algae: this organic fertilizer contributes 1% in nitrogen and 4% in potassium and phosphorus in an amount less than 0.75%. It also provides other nutrients in small amounts.

Having an idea of the composition of organic fertilizers, you can now use them by better controlling the dose of each.

4. How and when to fertilize sweet corn?


We have already seen the most important care for cultivation, we analyze what the NPK values are and we study what are the best fertilizers to be used in your sweet corn. It is time to see how and when to fertilize.

To make this analysis more useful, we will divide it between large and small crops.

4.1 Large crops

For this case we will apply inorganic and organic fertilizers together, maintaining a ratio of 1/20 respectively. This brings the advantage that the organic fertilizer acts as a sponge, absorbs and maintains the water in the soil.

We will use mixtures of fertilizers (15-15-15 and 12-12-17), chicken manure and urea. We will divide the fertilizations into three stages.

4.1.1 First fertilization

We will start by mixing 15-15-15 fertilizer with chicken manure in a 1/20 ratio. The quantity to place of each one will be:

  • 200 kg / ha of 15-15-15.
  • 4,000 kg / ha of manure.

This fertilization should be carried out before planting. Grooves about 10 or 15 cm deep should be opened, about 90 cm apart, where the fertilizer mixture will be placed. Once done, you can proceed with planting.

4.1.2 Second fertilization

Once the plant has developed sufficiently (approximately 50 cm in height), we can proceed with the second fertilization. In this case we will also add a little urea, being a 15-15-15 mixture, urea and manure in proportions 4/1/80. The amounts will be as follows:

  • 200 kg / ha of 15-15-15.
  • 50 kg / ha of urea.
  • 4,000 kg / ha of chicken manure.

The place where you should put the fertilizer should be on the side where the first fertilization took place. Once placed, water abundantly.

4.1.3 Third fertilization

The moment when this third and last fertilization must be carried out is when the plant begins to generate the first flowers. In this case, a 1/20 mix between 12-12-17 and chicken manure will be used. Quantities are:

  • 300 kg / ha of 12-12-17.
  • 6,000 kg / ha of chicken manure.

If you notice that in the flowering stage the plant is developing correctly and with great vigor, you can do without this last fertilization. If it does, do it on the opposite side of the second fertilization and accompany it again with a good irrigation.

4.2 Home growing

Let us now discuss the case of small sweet corn crops, such as the one you may have in your garden. As before, here we will also start with fertilization before planting.

Start by laying a layer of compost about 5 cm thick on the plot where you will plant. Then, in this layer, put a little fertilizer with a high amount of nitrogen (for example: blood meal, fish meal, etc.).

Using a garden tool, mix these fertilizers with the soil until a homogeneous mixture is obtained. After this, you can sow and water.

After this fertilization, you will have to wait until the plant is approximately 10 cm tall to add a 16-16-8 liquid fertilizer.

A third fertilization can be carried out when the plant is already at least 25 cm high, in this case the most recommended is to use urea or some nitrogen-rich fertilizer (46-0-0). Never fertilize too close to the stem as it can damage it (stay at least 15 cm away).

If deemed necessary, if the plant does not develop as vigorously as it could, it can end with a fourth fertilization. In this case, use a nitrogen rich fertilizer like urea again. When using fertilizers for commercial use, always follow the instructions on your container.

5. Fertilizing sweet corn with urea (video)


Urea is, without a doubt, one of the most widely used fertilizers, so this time we have selected a video (67 IH Farmer channel) where we will see how the correct way to apply it to your sweet corn crop is.

With this we have already reached the end of the article. I hope you are no longer in doubt about how and when to fertilize your sweet corn crop. 🙂

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