How to Add Potassium to Soil? 4 Useful Tips

If you want to know how to add Potassium to soil, then you have come to the right place. When it comes to the growth and development of plants, soil nutrients play a major role in it. One such nutrient is potassium. It is among the top three major nutrients (along with nitrogen and phosphorus) needed by plants to grow well. Giving your plants that much-needed potassium content will not only help them grow better but also produce more flowers and fruits.

Alongside this, this soil nutrient also helps them develop resistance to pests and fight off various plant diseases. Now, you know that to help your plants thrive, you need to ensure that your soil has enough potassium content in it. However, how does one do so? How to add potassium to the soil? If you want to know the same, keep reading!

Why is Potassium Important for Plants?

Before we tell you all about how much potassium we should add to the soil, and how to do so, let us first look at the functions of this mineral element in plants. Have a look:

  • It helps plants regulate the opening and closing of stomata for the uptake of carbon dioxide, and thus plays a role in enhancing photosynthesis.
  • This mineral also aids in the activation of some crucial biochemical enzymes that help in ATP synthesis and various other enzymes. These Adenosine Triphosphates then help plants generate the energy needed for their different chemical and physiological processes.
  • It, further, also plays a role in protein and starch synthesis along with managing osmoregulation of water and salts in cells and tissues of plants.

What are Some Signs of Potassium Deficiency in Plants?

 Some Signs of Potassium Deficiency in Plants

Now that you know why potassium is crucial for plants, let us see how to know that you need to add it to your soil. When it comes to potassium deficiencies, they are not easy to find. There are not many symptoms of these that are visually apparent. For instance, let us say that you have a lawn that lacks vigorous growth even in the prime growing season.

In such a case, you cannot straightaway say that your soil lacks potassium. It can be due to the lack of some other vital minerals, as well. Similarly, sometimes yellow leaves or blades of grass are a sign of a potassium deficiency. However, they may be due to the lack of nitrogen, as well. In such a case, how does one know that their soil is deficient in nitrogen?

Further, what if your fertilizer not only has potassium but also other minerals, and later it turns out that your soil does not need the other minerals? Let us say that one of the other minerals here is magnesium. How to add potassium without magnesium to the soil? To determine all of this, the most crucial step is a soil test. This will give you a clear view of what your soil needs and what it does not. So, you can act accordingly.


How can you Add Potassium to Soil?

Now that you know how to find out about a potassium deficiency, let us move on to the main topic of discussion in the post – how to add potassium to the soil. Here is everything you can do for the same:

Use Commercial Fertilizer

Based on your soil test, you can easily determine how much potassium will you need to add to your soil. Keeping this in mind, you can easily find a commercial fertilizer. For it, you can simply visit your local garden center, and find a variety of commercial potassium fertilizers. Alternatively, you can look for such fertilizers online.

A great example of this is greensand. As the name suggests, it is a kind of sand that is rich in glauconite and is found in the late-Cretaceous deposits of New Jersey. This potassium soil amendment is fossil-rich and low in sedimentary input. Along with potassium, it also has iron and magnesium.

This fertilizer can readily balance the potassium levels in your soil. Along with this, it also helps in improving moisture retention in soil, loosens it, softens hard water, and promotes root growth. Of course, greensand is not the only commercial fertilizer you can use. There are various others available for your use.

Once you decide which fertilizer you wish to use, it is time to ponder on other questions like – how much potassium to add to the soil per square foot. Typically, for every 1,000 square feet of soil, you will need to add 20 pounds of potassium fertilizer. This is especially true in the case of high deficiencies. For deficiencies that are low and medium, you only need to add 10 and 5 pounds respectively.

Further, while using fertilizers, you also need to take care of them when you are using them. For instance, if you are applying it to an already existing lawn, it is a good idea to do so when the soil is dry. Thus, the most appropriate time will be when the weather is cool in spring or fall. Also, it is a great idea to water in fertilizer to avoid burning the lawn grass or small plants.

Also, it is always ideal to use a spreader to disperse the fertilizer rather than just using it randomly. This ensures even spreading of it. Another thing that you need to take care of is the weather. Make sure that whenever you use a potassium fertilizer, there is no rain forecast for at least 24 hours. The purpose of this is to make sure that it does not seep into the water underground or water drains.

If your soil has only a potassium deficiency, use only a specialized fertilizer for it. If the same is not the case, you can even use a generalized fertilizer that contains nitrogen and phosphorus as well. You can easily find fertilizers of various NPK ratios for the same. Make sure to choose the NPK ratio that suits your soil and plants the most.


Use Kelp or Seaweed 

The next solution for how to add potassium to soil is with the help of kelp or seaweed. This solution is the best for those who live near the ocean and have easy access to a natural source of kelp or seaweed. You need to simply add it to your soil, and it will raise the potassium level easily. Now, the kind of seaweed you use will vary depending on whether you are using it on a lawn or a garden bed.

For a lawn, it is best to purchase a dried kelp meal or a liquid seaweed concentrate. In the case of the former, simply spread it over your lawn soil and rake it in. Make sure to do so in the quantities that are recommended. For the liquid seaweed concentrate, on the other hand, you need to spray it on your lawn. While you do so, make sure to do it evenly.

Further, when using kelp or seaweed for garden beds, the above-mentioned kinds may not be the most suitable choice. Your best bet is to look for natural seaweed. Once you have it, you can use it as mulch. This, then, over time will break down, and make sure to nourish your soil. If seaweed is something that is not readily available to you, fret not! We have other solutions for potassium deficiency, as well.


Use Wood Ash

The next thing that you can use is wood ash from a fireplace or wood heater if you have one. Do not throw away the ash from these in the trash. Instead, spread it thinly over your soil or lawn area. It is because this ash is high in potassium. However, if you are searching for how to lower the pH of the soil and add potassium to the soil, this may not be for you.

Usually, wood ash when used on soil can raise its pH, and make it more alkaline. Of course, if the pH of your soil is suitable to use ash (low), you can readily use it. Also, do so sparingly to prevent the plants from burning. Alternatively, you can simply add it to a compost pile, and use it with it.

Add Organic Matter

Organic Matter

The last method for how to add potassium to soil is by using organic matter. Compost is the best solution for it. This is nothing but decomposed vegetable scraps and green material and is surprisingly nutrient-rich. Also, it is cost-efficient and can be prepared at home. To make it rich in potassium, you can add banana peels to it. When using compost, you need to simply spread a thin layer of it, and then lightly rake it in.


Final Thoughts

So, this is how to add potassium to the soil. Whenever you decide to do so, it is always a great idea to get a soil test done first. After all, you do not want your soil to have an excess amount of potassium and other minerals as it can lead to toxicity. It, like a mineral deficiency, can be harmful to your plants, and even turn fatal. Therefore, always make a soil test your top priority.