Role of potassium nitrate in planting

In this new post on agriculture that we are taking up from Gardenprue, we are going to talk about fertilizing our crops. We give rise to potassium nitrate or potassium nitrate and comment on some things about this fertilizer widely used as fertilizer for many crops, production or not. Today we tell you a way to get some great fruits full of sugars. 🙂

The main fertilizer that has a crop is, as we have said other times, the NPK. This corresponds in order to nitrogen, phosphorus and potassium. Then we can also talk about other microelements that, depending on which crops, are also demanded, although in smaller proportions.


If we could establish a basic summary of the functions of these 3 compounds, we would say that nitrogen increases the vegetative density of the plant, phosphorus intervenes in the formation of roots and in the flowering and fruit set. P

Finally, potassium is responsible for improving the absorption of water and other nutrients by the roots, adding resistance to water stress and improving the organoleptic qualities of the fruits.

That, by way of summary, since both nitrogen, phosphorus and potassium have much more defined functions at the cellular level.


Potassium, as the main macroelement, is involved in a thousand and one functions within the plant. Let’s see them because it is a very interesting topic:

  • It is involved in more than 50 enzymatic processes
  • It is necessary to carry out essential processes such as respiration, photosynthesis or the production of chlorophyll.
  • Increases the resistance of plants to drought, frost, hail or any agent that causes stress on the plant.
  • In the fruits, it increases its weight, favors the change of color due to maturation and increases the pre-harvest time.
  • It favors the action of nitrogen applied to the soil.


What we are looking for in a watermelon or melon, to give a clear example, is that, apart from having “freshness”, they are sweet. It will not be the first time that a farmer has been seen to add sugar to the earth thinking that the plant is capable of assimilating said sugar and passing it to the fruits, something totally unnecessary and classified as absurd.

The sugar that these fruits may contain is not the sugar itself, since among the disaccharides there are many compounds , such as lactose, fructose or maltose. In this sense, there are several studies that confirm the close relationship between nitrogen and potassium and the acidity and sweetness of the fruits.


This is where potassium nitrate comes into play, since used in a convenient way both in time and in quantity, it allows to develop a fruit with good flavor. Be careful, not everything depends on the subscriber, because the water and the environment also influence.

In this case, potassium nitrate, as we see by its name, has a nitrogen part and a potassium part. The amounts can be known with a few simple calculations, as we saw in complex fertilizers .

We worked with fertilizer units (UF), a dimensionless measure that establishes the exact amount that we add to a compound. Let’s look at the following example:

Potassium nitrate is a binary fertilizer , since it only has nitrogen and potassium. It comes with the 13-0-46 ratio. That means it has 13 UF of nitrogen, 0 UF of phosphorus and 46 UF of potassium (which is interesting, in this article).

Knowing the amount we apply to the soil in order to fertilize our plants is simple. Normally we will find this fertilizer in bags of 25 kg, with which, for this quantity, we have the following values:

  • Nitrogen: 3.25 kg / bag
  • Phosphorus: 0 kg / bag
  • Potassium: 11.5 kg / bag

These are the exact amounts that we apply to the soil with potassium nitrate in the amount mentioned above.


The information that we can find on the potassium nitrate label is merely indicative, since it does not take into account the type of soil you have, the variety of the crop or the age, much less the quality of your irrigation water (which It will tell us what is the subscriber limit that we have so that there are no burns or loss of performance).

  • Fruit trees: 250-350 kg / ha
  • Citrus: 250-350 kg / ha
  • Vegetables: 200-500 kg / ha
  • Olive tree: 175-200 kg / ha
  • At: 200-300 kg / ha

Finally, mention that there are also alternatives in terms of fertilization if you want to do without adding more nitrogen to the soil. This happens when we need to stop the growth of the crop or our soil already has adequate levels of this compound.

An example would be the use of potassium sulfate or some liquid potassium solutions that are on the market. For the first case, it usually has a concentration of between 50 and 52% (you already know how to get the values ​​of the fertilizer units) and potassium solutions vary a lot in their composition in potassium. There can be from 8%, 20%, 30%, etc. The good thing about these solutions is that they have chelating agents (such as EDTA: ethylenediaminetetraacetic acid)  and that they have low or no levels of chlorides. For this reason, its assimilation is rapid by the roots of the plants and, in addition, it has a regulatory effect on the absorption of other very important minerals such as calcium or magnesium).

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