How To Add Potassium To Soil

The full extent of potassium’s impact on gardens is still unknown. However, potassium’s impacts on plants are well known because it is considered organic and boosts a plant’s ability to grow and produce.

You don’t need to know the entire how’s and whys plants are harmed by potassium deficiency as a gardener, and it’s not uncommon for plants and crops to be deficient in this nutrient.

If you add it to your soil, potassium will help your plants grow faster and produce more flowers and fruit.

It also contributes to the fight against disease and insect resistance of plants. Plant diseases like rust and powdery mildew are less likely to weaken a healthy, growing plant.

potassium on soil

In our guide, you can learn more about how to increase potassium in soil for your crop needs. By the end, you’ll have all the information about growing plants to the optimum by adding potassium sources that are healthy and organic. (Learn How To Add Phosphorus To Soil)

What Is The Best Source of Potassium For plants?

Potassium is necessary for plant development and growth. Potassium helps plants grow quicker, be water-efficient, and be drought-resistant. It can help defend against sickness and pests and increase crop production.

Potassium helps nearly all plant growth operations, yet it isn’t a part of the plant tissue and is found in the fluids inside plants. A plant with enough potassium will be a better plant overall.

Potash is a naturally occurring chemical found in potassium fertilizers. This is nothing more than wood ash and a typical element of the ecological cycle of growth and decay. Potash can also be found in the seas and mines in its natural state.

Most commercial fertilizers contain potassium. It’s the K in the N-P-K decomposition. Potassium-only fertilizers, such as muriate of potash (potassium chloride) and sulfate of potash, are also available (potassium sulfate).

You can discover natural potash in wood ash, seaweed (kelp meal), and compost if your compost is built from a high proportion of vegetable waste. Banana skins provide some of the highest quantities of potassium out of any source. Banana skins contain some of the highest levels of potassium out of any source. (Find the Best Liquid Lawn Fertilizer Concentrate)

How do you fix potassium deficiency in soil?

Potassium deficiency in plants causes poor overall performance. So it’s tough to spot potassium deficiency in plants. You can, however, see some signs in the leaves, such as brown dots, yellow margins, yellow veins, or brown veins appearing on older leaves.

Potash fertilizer is another name for potassium fertilizer. Because potassium fertilizers often contain potash.

While potash is a naturally occurring chemical, only some potassium fertilizers with potash are organic. Some sources claim high potassium fertilizer, a pure potassium fertilizer, or one with a high “K” value.

The “big three” soil nutrients are phosphorus, potassium, and nitrogen. Phosphorus and potassium are the last two numbers on the bags of 10-10-10, 5-20-20, and so on.

Phosphorus promotes flowering and root growth, whereas potassium aids disease resistance and nutrient uptake.

There are various organic and synthetic ways of adding potassium to the soil if it lacks phosphorus and potassium.

Here’s how to add potassium to the lawn or soil around your garden.

Method 1

  1. Use a simple soil test device to determine the phosphorus and potassium levels in your soil. After this, you can calculate how much fertilizer to use once you know if your soil is extremely low, moderately low, or slightly low in either or both nutrients.
  2. Weeds and other plants should be removed from the garden bed or area.
  3. Smooth the garden bed with a rake.
  4. To add phosphorus to the soil, scatter bone meal on top of your garden bed.
  5. Apply 30 pounds – severely deficient, 20 pounds – moderately deficient, and 10 pounds on slightly deficient soil per 1,000 square feet.
  6. For potassium, spread kelp meal on the ground.
  7. Use 20 pounds – severely deficient, 10 pounds – moderately deficient -, and 5 pounds for slightly deficient soil per 1,000 square feet.
  8. Use a spade or a tiller to work the two soil amendments into the top 8 to 12 inches of soil.
  9. To allow the nutrients to be absorbed throughout the bed, water the garden thoroughly.

Method 2

  1. With your soil test kit, analyze your soil’s phosphorus and potassium levels.
  2. Remove any weeds and unwanted vegetation from the garden bed or area.
  3. Rake your garden bed smooth.
  4. On top of the garden bed to add phosphorus to the soil scatter rock phosphate. For every 1,000 square feet, apply 60 pounds for severely deficient soil, 25 pounds for moderately deficient soil, and 10 pounds for slightly deficient soil.
  5. For potassium, spread granite meal or greensand on the ground. For both amendments, the proportions are the same. Per 1,000 square feet, you would use 100 pounds for severely deficient, 50 pounds for moderately deficient, and 25 pounds for slightly deficient soil.
  6. Use a spade or a tiller to work the two soil amendments into the top 8 to 12 inches of soil.
  7. To allow the nutrients to be absorbed throughout the bed, water the garden thoroughly.

Method 3

  1. Analyze phosphorus and potassium levels in your soil using a home soil test kit.
  2. Remove any weeds and unwanted vegetation from the garden bed or area.
  3. Rake your garden smooth.
  4. Broadcast a commercial N-P-K fertilizer mix. Choose a combination like 10-10-10 with at least as much phosphorus and potassium (the second two digits) as nitrogen (the first number).
  5. Choose a blend with a higher last two numbers, such as 5-20-20 or higher, if your soil is moderately to severely lacking in phosphorus and potassium. Follow the directions for the fertilizer amount for your square footage and current phosphorus and potassium levels.
  6. Work your fertilizer into the top 8 to 12 inches of soil using a spade or tiller.
  7. Water the garden thoroughly to allow the nutrients to be absorbed throughout the bed.

How Can I Get Potassium In My Plants Naturally?

You can add potassium, the naturally occurring substance, and what is considered organic to your soil without using potash or other commercial potassium fertilizer.

Compost formed from food waste is high in potassium, and banana peels are a rich potassium source.

1. Kitchen Waste and Compost

Compost your fruit and vegetable waste. Banana peels, which are high in potassium, should be cut into small pieces and added to your compost pile. To avoid potassium leaching, keep your compost covered. When you’re not using your compost heap, use a closed container or cover it with a tarp. Because potassium compounds are water-soluble, they can be easily washed out of your compost by rain. (Read What Is Mushroom Compost)

Fill a spray bottle halfway with warm water and extra banana peels. Allow two weeks for the banana peel to ferment in the water before spraying the organic potassium liquid on the plant soil.


2. Wood

When the fire is out, collect the potassium-rich ashes. As you build your compost pile, sprinkle a few ashes on each layer. Before moving on to the next layer, wait for the ashes to disintegrate.

Add hardwood ashes only if you have to increase your soil’s pH. Because of this, don’t use wood ash fertilizers for acid-loving plants, such as azaleas or blueberries.

Wood ash raises soil pH or decreases acidity, so when you use hardwood ashes to supply your garden with potassium, regularly test soil pH to ensure the soil is balanced. Sprinkle 1 to 2 pounds of ash per 100 square feet or add in small amounts based on pH levels.

3. Coffee

Use your used coffee grounds. To use, dig 6 to 8 inches into your soil solution or plant container and add the coffee grounds into the soil.

4. Muriate of Potash

Potassium muriate, also known as potassium chloride, and potassium sulfate, sometimes known as potassium sulfate, are both naturally occurring substance. Muriate of potash is less expensive, yet the chlorine can harm beneficial bacteria in your garden soil. Potash sulfate is a safer alternative, but it is more expensive. For both, check the product label for details on how much to add per square foot.


5. Seaweed

Kelp meal and other varieties of seaweed contain a lot of potassium and release it quickly into the soil to correct a potassium deficiency in the soil. You can either incorporate a few handfuls of dried kelp meal into the soil or use a water-soluble seaweed spray. Per square foot of soil, add one pound of kelp meal for optimum plant growth.

6. Sulfate of Potash-Magnesia

Sul-Po-Mag is an affordable option. Use when your soil test shows your soil is low in potassium and magnesium. You most often use this product if your garden soils require sulfur.

7. Granite dust

Granite dust is a relatively affordable product that is got from natural granite quarries. It releases potassium slowly, like greensand, so it won’t work well if you need a quick fix for potassium deficiency and crop growth.

Tips for adding potassium content to the soil.

If you notice signs of shortage, supplement with potassium. Yellow leaves and brown leaf edges are signs of a deficit. Older leaves, or those near the bottom of your plant, are more prone to discoloration. You may see uneven ripening or yellow areas on the fruit of fruiting plants such as tomatoes.

If you have sandy soil, monitor your plants as potassium quickly leaks from soil because of its high solubility, especially in coarse, sandy soils. If you suspect that leaching is a problem, keep a close eye on your plants. Test your soils on a more regular basis.

Leaching can be prevented by amending your sandy soil with manure and well-rotted compost.

Examine your body for indicators of magnesium insufficiency. More potassium can reduce the number of other nutrients absorbed by the plant. Because potassium competes most directly with magnesium, watch for yellowing between the veins of the leaves. Although the veins themselves remain green, the gaps between them turn yellow.

If adding potassium causes or worsens yellowing, purchase an organic calcium-magnesium supplement or magnesium sulfate. You’ll either mix it into the soil or spray it on the bottom leaves of your plant, depending on the product.

How To Add Potassium To Soil (2)

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