What is potassium sulfate and what is it for?

Potassium sulfate

The plants they need a series of nutrients to be able to grow and developsuch as phosphorus, nitrogen and calcium. All of them are very important, so much so that the excess or lack of one of them will make them sick in a matter of time, which can be more or less long depending on its importance. Thus, if you have a lack of iron, your leaves will immediately become chlorotic and stop growing, but if you have a lack of boron it will take longer to show symptoms.

With this in mind, it is essential that they are paid regularly to prevent them from getting sick. With what? It will depend on the type of plant and what we are interested in achieving. This time we are going to focus on the potassium sulfatea fertilizer that will help control the maturity and fattening of the fruits.

What do plants use potassium for?

Melon plant

melon plant

Potassium is found in the soil from silicates from rocks and magmatic minerals such as micas and feldspars. We can distinguish three types:

  • Directly assimilable potassium: which is the one that is fixed on the surface of the clays and in the clay-humic complex.
  • Interlaminar potassium: it is found between the sheets of clay. Roots have a hard time absorbing it.
  • Potassium in mineral fractionIt is found in the soil, but cannot be absorbed by plant roots unless it is broken down by bacteria.

This nutrient has very important functions for the plants:

  • It ensures that the cells do not lack water, so it is related to the fattening and quality of the fruit.
  • It controls the permeability of the cell membranes, which means that the less water is lost, the better the fruits will be preserved.
  • It contributes to improving the cold resistance of plants by regulating the saline concentration of cellular juices.
  • Improves resistance to drought, as it reduces the speed of perspiration.
  • It helps to make sugars, giving the fruit a sweet taste.

What is potassium sulfate?

Potassium sulfate is the potassium salt of sulfuric acid. It is one of the most interesting fertilizers for growing plants, especially aquatic ones, since it is free of chlorine. It combines two essential nutrients: potassium and sulfur, both assimilable by plants.

Normally, the quantity and richness of this fertilizer is of a 50%and this is related to the fertilizer units (UF). To establish the amount of potassium fertilizer that is added to a crop (according to UF) and potassium sulfate, it is done through the following relationship:

100 FU of potassium for a culture = 200kg of water-soluble potassium sulfate, K2O (50%).

When can it be used?



Potassium sulfate is a fertilizer that can be used throughout the entire fruiting seasonthat is, from the first moment in which the flower is pollinated until two weeks before the harvest of the fruits. But, yes, it can only be used if we have an alkaline soil, that is, with a high pH, ​​since it also serves as a pH reducer.

As a recommendation, if irrigated by sprinkling, you can add between 1 and 2,5 grams / liter of water; and if it is drip from 2 to 9kg per 100 liters of water. Even so, you should know that the amount can vary depending on the pH of the soil, so before starting to fertilize the plants with it, it is important to perform a soil analysis as the soil may have adequate potassium levels and therefore potassium sulfate fertilization is unnecessary.

The crops that best respond to this fertilizer are fruit trees, banana trees, legumes, cabbages, among others.

How much potassium do plants need?

It will depend on the type of plant, but those that are grown for their leaves and / or fruits need a lot. For example (taken from the Practical Guide of Rational Fertilization of Crops in Spain):

Outdoor crops:

  • Broccoli (15/20 t / ha): 370-450kg / ha
  • Spinach (22-28 t / ha): 180-220kg / ha
  • Melon (30-40 t / ha): 250-330kg / ha
  • Watermelon (45-55 t / ha): 180-220kg / ha
  • Tomato (55-65 t / ha): 300-330kg / ha

How do I know if my plant is lacking in potassium?

If the plant is potassium deficient, it will show these symptoms:

  • Chlorosis: the middle and lower leaves will start to look yellowish, starting at the edge inwards.
  • Slow growth, practically zero: not having enough potassium, the plant will hardly grow.
  • Less resistance to cold and lack of water: There will be less water that circulates through the plant as a result of the lack of potassium, so it will become more susceptible to cold and droughts.
  • Defoliation: if the deficiency is not corrected, the plant could lose all the leaves.
  • Uneven fruit ripening: potassium is very important for fruit development; If it is not present in sufficient quantities, they will not be able to ripen properly.
  • Low resistance to pests– When it does not have everything it needs, the plant becomes weak, so it cannot defend itself against pests.

Young plant

young plant

And with this we are done. As you have seen, potassium is an essential element for plants, with potassium sulfate being a highly recommended fertilizer so that they can grow without problems.

What is potassium sulfate and what is it for?

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