Achieving the right soil pH is essential for plant health and growth. Alkaline soil (pH above 7) is beneficial for certain plants and helps with nutrient availability.
Understanding how to increase soil alkalinity naturally can lead to healthier plants and improved yields. In this article, we’ll explore natural ways to raise your soil’s pH and make it more alkaline.
Factors Affecting the pH of Soil
Soil pH is influenced by several factors. These include the parent material, organic matter content, and rainfall [1].
Acidic soils often develop in regions with high rainfall because rain leaches away calcium and magnesium, which are alkaline-forming elements.
Soil with high levels of organic matter tends to be more acidic. On the other hand, soils formed from limestone are typically alkaline.
Other factors that affect soil pH include fertilizer use (acid-forming fertilizers lower soil pH), decomposing plant material, and natural weathering of minerals.
Things to Consider Before Adjusting Soil pH
Before adjusting soil pH, it’s crucial to understand the needs of your plants. Some plants thrive in acidic soil, while others prefer alkaline environments.
Therefore, adjusting the pH too much in one direction can affect the availability of essential nutrients, potentially harming plant growth.
Factors to consider before making changes:
- Plant type: Know the pH preference of your plants.
- Soil type: Sandy soils respond to pH changes faster than clay soils [2].
- Current soil pH: Testing your soil’s pH is vital to determine how much adjustment is necessary.
- Water: Alkaline water can also raise soil pH over time.
Soil pH Testing
To test your soil’s pH at home, you can use a pH test kit, available at garden centers, or use a simple DIY method. Here’s how:
DIY Vinegar and Baking Soda Test:
First, collect soil samples from different areas of your garden. Next, place about 1 tablespoon of soil into a small container.
Finally, add a few drops of vinegar. If the soil fizzes, it’s alkaline.
If there’s no reaction, add a little water to another sample. Next, sprinkle baking soda over it. If it fizzes, the soil is acidic.
A more precise method is to use a digital pH meter or soil pH test strips.
How to Make Soil More Alkaline Naturally
Now that we’ve covered the basics of soil pH, let’s explore some natural ways to raise the alkalinity of your soil.
However, be very careful not to overdo it. If the soil becomes too alkaline, many plants may have difficulty absorbing important nutrients.
1. Wood Ashes
Wood ashes are a quick and natural way to raise soil pH. They contain potassium, calcium, and magnesium, which are alkaline-forming nutrients.
To apply, first collect ashes from a clean wood-burning source. Avoid ashes from treated or painted wood [3].
Once cooled, spread a thin layer of ash, no more than 1 inch thick, across the soil surface. Work the ashes into the topsoil gently to help it blend evenly and prevent runoff.
Since wood ash is high in calcium, potassium, and other alkaline minerals, it raises the soil’s pH. However, over-application can cause pH levels to spike too high, which could harm plants.
Therefore, apply ash gradually and test your soil’s pH regularly to monitor its effects.
2. Agricultural Lime
Agricultural lime (also called garden lime) is one of the most common and effective ways to make soil more alkaline.
To use, first determine the current pH of your soil and the type of soil you’re working with. This will guide how much lime to apply.
For clay soils, you’ll need more lime compared to sandy soils, as they require more effort to raise the pH.
Now spread the lime evenly across your soil surface using a broadcast spreader or by hand for smaller areas. Next, work the lime into the top few inches of soil using a rake or tiller for better absorption.
Lime works gradually, so it may take several months to see the full effect [4].
3. Baking Soda
Baking soda is another household item that can help raise soil pH. However, it’s best used for small, contained areas like pots or small garden beds.
To use, mix about 1 tablespoon of baking soda into 1 gallon of water. Stir the solution until the baking soda is fully dissolved.
Then, use this mixture to water the soil around your plants, applying it evenly to the areas where you want to raise the pH.
4. Oyster Shell Lime
Oyster shell lime is made from crushed oyster shells, which are rich in calcium and magnesium.
It’s slower-acting, which means that it slowly helps neutralize soil acidity. This makes it a gentler option compared to other remedies.
Since oyster shell lime works overtime, regular soil pH testing will help track progress and prevent overapplication.
5. Eggshells
Pulverized eggshells are also a great way to add calcium to the soil and slightly raise pH over time.
To use, start by collecting and thoroughly cleaning the shells to remove any residue.
Once dry, crush the eggshells into a fine powder or small pieces. The finer the texture, the faster they will break down in the soil.
Next, sprinkle the pulverized eggshells evenly around the base of your plants or directly mix them into the top layer of soil.
The powdered eggshells will gradually raise soil pH as they decompose. This makes them a gentle and slow-release option for increasing alkalinity organically.
This home remedy is also best for long-term pH adjustment. Therefore, it’s important to regularly monitor the soil’s pH over time to ensure it reaches the desired levels.
6. Bone Meal
Bone meal also helps to raise soil pH slightly. It’s a great addition for flowering plants and root crops.
To apply, sprinkle it evenly across the soil surface or mix it into the soil when planting.
However, be sure to follow the recommended dosage on the packaging. Also, test your soil’s pH periodically to monitor the effects and avoid overapplication.
7. Dolomitic Lime
This is similar to agricultural lime but contains a higher magnesium content. It’s a great choice for soils that are both acidic and deficient in magnesium.
To use, begin by determining your soil’s pH and magnesium levels. Next, spread the lime evenly across your soil surface using a broadcast spreader for larger areas or by hand for smaller patches.
Work the lime into the top few inches of soil to ensure it mixes well. Dolomitic lime also works gradually, so it can take several months to fully adjust the soil’s pH.
Plants That Prefer Alkaline Soil
Many plants do well in alkaline soil. These include lavender, clematis, carnation, hydrangeas, and lilac.
Certain types of vegetables, like beans, cabbage, kale, and beets, also do well in alkaline soil.
Takeaway
Raising soil pH naturally takes time and care. But it can be a rewarding process that helps your garden thrive.
Whether you choose to use lime products, wood ashes, or household items like eggshells and baking soda, make sure to monitor your soil’s pH regularly and adjust accordingly to ensure healthy plant growth.
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