Is Potassium Sulfate Soluble And How To Use It In The Soil

Last Updated on October 26, 2022 by Sam

The one important question most farmers have not found adequate answers to, “is Potassium Sulfate soluble and how to use it in the soil”? Here we discuss this fertilizer so that farmers can have a better understanding.

Potassium sulfate is an excellent source of Potassium for plants. It provides the much-needed Potassium minerals in a stable Ph neutral form. With some brands certified as organic, you can choose from a variety.

Potassium fertilizers come in different types.  If you don’t understand their differences, it is difficult to distinguish them.  Potassium sulfate is the best choice for both organic and conventional gardeners.

Is Potassium Sulfate Soluble?
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Not all Potassium Sulfate fertilizers are alike. There are synthetic potassium sulfates and organic certified. Potassium sulfate that comes from natural mining sources is the one that is certified organic. This Potassium has not undergone any kind of further processing.

Is Potassium Sulfate Soluble?

Unfortunately, some unprocessed raw materials are not soluble. They carry unwanted minerals that do not help the plant. Only a few sources of organic potassium sulfate are soluble. Knowledgeable sales staff should be able to tell you the source of their fertilizers. And whether their product is soluble or not.

Potassium sulfate does not dissolve easily.  Generally, only a 1/3 is soluble.  Most of it does not dissolve especially through irrigation.

It is also important to know the grade of the Potassium fertilizer you are buying. Large particles of Potassium Sulfate are barely soluble and not a good choice. The best grade is the fines with small particles about 0.015mm and below. Fine grades dissolve easily and are better to use in foliar sprays or irrigation.

Check this organic fertilizer from Down to Earth that provides a source of potassium, magnesium, and sulfur for your plants.

Essential Functions of Potassium Sulfate in Plants

Potassium sulfate helps to complete a majority of essential functions in plants. Some of these functions include:

  • Activating enzyme reactions
  • Synthesizing proteins
  • Forming starch and sugars
  • Regulating water flow in leaves and cells

In most cases, Potassium in the soil is too low to support healthy plant growth. And for this reason, you can choose to add Potassium Sulfate to your plants.

How To Use Potassium Sulfate In Soil

Potassium deficiency in plants usually show signs on the leaves as they turn yellow. To provide fast-acting potassium to such plants, it is best to use foliar feeding sprays. The foliar spray made from clean water and soluble Potassium stops the problem from spreading.

Highly concentrated Potassium fertilizer can burn the leaves. Be sure to use mild concentrations of foliar sprays. You would rather spray mild concentration many times rather than use the concentrated one.

The application rate depends on the quality of your soil.  Apply 2 pounds of Potassium sulfate per 100 square feet or 2 tablespoons per gallon of water.

How To Use Potassium Sulfate In Soil


What is the best way to add potassium to soil?

Potassium (K) is one of the most important plant nutrients. It is present in soil in different forms and functions as a catalyst for many plant processes. In general, potassium is an essential nutrient for plants. It is not readily available from the soil. Plants can absorb potassium only when it is present in solution (e.g., in water). The amount of potassium in soil is very low and is also easily leached by rainfall and irrigation.

The best way to add potassium to soil is to apply potassium fertilizer in the form of potassium chloride. This material is soluble and has a high concentration of potassium. It is very easy to work with and can be applied either as a liquid or as granules. However, if you want to get the most out of your potassium fertilizer, you need to know how much potassium fertilizer to use. If you do not know the right amount, you will not get the full effect of your application. Potassium is an important plant nutrient. It is needed for proper development of roots and other plant parts. Plants absorb potassium from the soil. They cannot take potassium directly from their food (plants use photosynthesis to produce energy). Instead, they absorb potassium from the soil. You need to supply potassium to plants in two forms: organic and inorganic. Potassium in the form of organic material is found in soil and in organic matter that has been added to the soil. It can also be found in fertilizers. Potassium in the form of inorganic material is found in fertilizers.

How do you make liquid potassium fertilizer?

Plants use potassium to help build strong cell walls, improve photosynthesis, and maintain proper cellular levels of electrolytes. Potassium is an essential nutrient for plants and is considered a macronutrient. Like many other nutrients, potassium is used by plants in small amounts. Most plants will use potassium at the rate of 1% of their dry weight. To make liquid potassium fertilizer, mix a 1-pound bag of granular potassium chloride with water and stir to dissolve. Add 1/4 pound of magnesium sulfate per gallon of water and stir again. Filter the mixture through a fine mesh strainer to remove any remaining solids. Store the fertilizer in a glass container.

What plants need a lot of potassium?

Potassium is an essential mineral for plant growth. It is needed in the formation of chlorophyll, and it also helps regulate water and sugar levels in plants. 

Potassium is also involved in the production of chlorophyll, and is used to make cell walls and connective tissue. Plants require potassium to help them absorb nutrients from the soil.  The amount of potassium you need to feed your plants depends on several factors. These include:

The type of plant you're feeding. Plants that are grown in soil tend to require more potassium than those that grow in water. Some types of plants, such as tomatoes, require only a small amount of potassium to grow. Other plants, such as cacti, will need a lot of potassium. The time of year when you feed the plant. When you feed a plant in the spring, it will absorb more potassium than it will when you feed it during the summer.


Just like the human body, plants also experience a lack of necessary nutrients. A fertilizer that replenishes the plant’s nutrients is the same as supplements that humans need. Likewise, as you take your supplement today, be sure to check if your plants need some!