Potassium Fertilizers: Effects, Importance, and Deficiency

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potassium fertilizer

Do you know that other than nitrogen, Potassium fertilizers are one of the most important plant nutrients?

Potassium, K is one of the important nutrients that your plants need in large quantities and it does not become part of complex organic molecules in your plants.

It moves and performs many of its functions as a free ion like regulating plant water pressure, activating enzymes, balancing electrical charges, transporting sugars and starches, and more.

Potassium fertilizers come from a variety of potassium salt deposits from around the world.

These salts are then processed to remove purities and then converted into a variety of fertilizers.

Two of the most popular potassium fertilizers are potassium chloride and potassium sulfate.

However, the term potash is a general term for a variety of potassium fertilizers or in some cases, for potassium chloride.

Farmers often refer to potassium chloride as “muriate of potash” or MOP, while potassium sulfate is “sulfate of potash.

Keep on reading.

Role of Potassium in Plants

Potassium is one of the most important nutrients that help to sustain plant growth and reproduction.

However, if your plants are deficient in potassium, they are less resistant to drought, excess water, and high and low temperatures.

Furthermore, they are also less resistant to pests, disease, and nematode attacks.

As potassium improve the overall health of the growing plants and also helps them to fight diseases.

It is known as the “quality” nutrient.

Potassium affects factors like size, shape, color, and vigor of the seed or grain and also improves the fiber quality of cotton.


Moreover, potassium increases crop yields because it:

  • increase root growth and improve drought tolerance
  • aids in photosynthesis and food formation
  • builds cellulose and reduce lodging
  • helps to translocate sugars and starches
  • increase the protein content of plants
  • maintain turgor, reduce water loss and wilting
  • helps retard the spread of crop diseases and nematodes

Potassium Uptake by Crops

The time of potassium uptake often depends and varies with different plants.

However, most often plants absorb the majority of their potassium at an earlier growth stage than they do nitrogen and phosphorus.

According to the experiments on potassium uptake by corn, about 70 and 80% absorbs by sinking time and 100% of it absorbs 3 to 4 weeks are silking.

Moreover, the translocation of potassium from the leaves and stems to the gran is also less than that of phosphorus and nitrogen.

The period during grain formulation is apparently not a critical one for the supply of potassium.

potassium fertilizer forms

It is important to note that the potassium content of fertilizers is expressed as K2O, though there are no such compounding fertilizers nor is it absorbed by or found in plants.

Some crops uptake of potassium is as follows:

  • Alfafa: 600 lb/acre
  • Corn: 66 lb/acre
  • cotton or lint: 210 lb/acre
  • Grain sorghum: 240 lb/acre, etc

Removal of Potassium by Crops

Nutrient uptake or utilization is an important consideration, however, crops take up far more potassium than they will remove with the harvested portion.

For instance, a 22 bu/acre crop will take about 266 lb/acre of potash, however, when you will harvest then the corn as grains, only 0.25 lb/bu will be used, or 50 lb/acre of K2o is harvested.

However, if you harvest the crop as silage, then 7.3 lb/ton K2O are vested and removed from the field.

Often will hay and silage, removal is an excellent guide for planning the potash fertilization program. While for other crops like grain, soil tests ofter the best guide.

Consider some of the potassium removals by some of the crops are:

  • corn grain: 0.25 lb/bu
  • corn silage: 7.30 lb/bu
  • cotton: 19.0 lb/bu
  • rice grain: 0.16 lb/lu
  • sugarcane: 3.50 lb/bu
  • spring wheat grain: 0.33 lb/bu, etc.

Symptoms of Potassium Deficiency

Potassium is a highly mobile element in the plant and is translocated from the older to the younger tissues.

Consequently, potassium deficiency symptoms often occur first on the lower leaves of your plants and progress toward the top as the severity increases.

Moreover, one of the most common signs of potassium deficiency is the yellow scorching or firing (chlorosis) along the leaf margins.

However, in severe cases, the fired margin of the leaf may also fall out.


With broadleaf crops, like soybeans and cotton, the entire leaf may shed, thus resulting in premature defoliation of your crop.

Moreover, potassium-deficient crops grow slowly and have a poorly developed root system.

Stalks are weak and the lodging of cereal crops such as corn and small grain is also common.

On the other hand, legumes are not strong competitors for soil potassium and are often crowded out by grasses in the grass-legume pasture.

When potassium is not sufficient, winter kitting of perennial crops like alfalfa and grasses can occur.

Balanced Crop Nutrition and Potassium

Adequate supplies of other plants are also important to obtain maximum responses to potassium fertilizers.

However, there are different unique relations between potassium and other nutrients.

High-potassium fertilizer can also decrease the availability of magnesium to your plants and may result in magnesium deficiency.

This will occur when your crop grows on sandy soil, particularly on soils high in magnesium can suffer potassium deficiency.

On the other hand, when you grow crops on soils high in magnesium can suffer from potassium deficiency.

Leaching of potassium in acidic, sandy soils can also reduce by liming the soil to a pH of 6.2 to 6.5.

However, applications of high rates of limestones to soil that is low in potassium may induce potassium deficiency.

This problem is more common on soil with predominantly 2:1 type clays like montmorillonite clays rather than 1:1 type like kaolinitic clays.

Potassium Fertilizers

Elemental Potassium K is not found in a pure state naturally as it is highly reactive.

You can purify it, however, you must keep it in oil to retain its purity and prevent violent reactivity.

Furthermore, potash deposits occur as beds of solid salts beneath the surface of the earth and brine in dying lakes and seas.

Good potassium is important to consistently improve crop productivity.

potassium fertilizer 1

The role of potassium fertilizer in plant/soil/air-water retentions is to activate certain enzymes.

Moreover, it aids in moving captured carbon from plant biomass to reproductive material, like grains, fruit, and fiber.

At Al Ardh Alkhadrah, our product Giant Fruit is a 100% organic general stimulant that contains macro and micronutrients.

Moreover, it contains vitamins, amino acids, auxins, humic acid, and rooting hormones.

You can use it for all trees, vegetables, fodders, and weeds.

Additionally, it increases productivity, vegetation, and flowering while preventing fruit loss, reducing salinity, and lowering the pH.

Placing Potassium Fertilizers

You can place potassium fertilizers in two ways:

  • Placement
  • Broadcast

Let’s discuss them as follows:


The common potassium fertilizers are water-soluble and in some cases, they have a high salt index.

Moreover, when you place them too close to seeds or transplants, they can decrease seed germination and plant survival.

The fertilizer injury it causes to your plats is most severe in sandy types of soil, under dry conditions, and with high fertilizer rates, especially nitrogen and potassium.

Some crops like soybean, cotton, and peanuts are even more sensitive to fertilizer injury than corn.

Placement of the fertilizer in a band appro. 3 inches to the side and 2 inches below the seed is an effective method of preventing fertilizer injury.

Furthermore, the placement of potassium fertilizer is generally more efficient than broadcast application.

This is because the rate of application is low or soil levels of potassium are low.



Broadcast application of potassium under minimum tillage often results in much-applied potassium remaining in the top 1 to 2 inches of the soil.

Whereas, with conventional tillage, you can distribute it throughout the plow layer.

A corn often absorbs sufficient potassium under no-till due to its extensive root system in the surface layer of the soil.

Leaf analysis of corn shows lower potassium content under minimum tillage than conventional methods due to either location of the potassium you apply or to poorer aeration.

Sufficient potassium can be supplied by using a higher rate of potassium fertilization with no-till systems.

Soil Cycle of Potassium

In the following diagram, you can see 3 different factors that affect potassium within the potassium cycle and components in the soil.

potassium cycle

Let’s discuss them:

Unavailable Potassium: Approx. 90-98% of total soil potassium is present in this form.

Minerals contain potassium and break down over time releasing it. Moreover, this is a long and slow process that moves potassium in small amounts to the readily available pool.

Slowly Available Potassium: This form of potassium is trapped between layers of clay minerals and is also referred to as being fixed.

Some of its releases for plats during the growing season, however, some remains fixed between the clay layers and slowly converts to available potassium.

Readily Available Potassium: This one is available for the growth of plants present in the soil and hold on soil exchange sites.

Plants are able to absorb it readily in the soil water. As soon as the potassium in the soil water concentration drops, additional potassium is released into the soil solution.

Current soil testing techniques can quantify the amount of potassium your soil exchange sites hold.

This information can help to inform whether you need to add potassium fertilizer and how much to supply.

Thus, with the help of proper supplementation of potassium fertilizer your plants will have the ability to perform important functions crucial for their survival and the fruits of your plants.

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