The quality of the soil affects the nature and health of the plants in your garden, and every gardening enthusiast needs to understand the effect of pH to make sure that plants have access to all the nutrients they need.
As the pH level changes, several nutrients become more available in the soil. This is why there’s always a recommended pH level for every plant species you’re trying to grow.
So, how can you change the pH level in your garden’s soil? There are multiple factors affecting the pH of the soil, as well as multiple ways to either raise it or lower it.
Factors Affecting Soil pH
The soil’s pH level refers to the concentration of hydrogen ions in the ground, and it can range from 0 to 14. A pH level of 7.0 is considered neutral, while anything below 7.0 is considered to be acidic, and anything above 7.0 is alkaline. There are different factors that affect the pH level of the soil, and some of them can be controlled to adjust the soil acidity.
- Climate has a massive impact on the acidity of the soil. In warm and humid areas, the continuous rainfall eventually decreases the pH level of the soil, so it becomes more acidic. The high amount of rain causes leaching that weathers the soil minerals. In drier environments, the soil is more likely to be neutral or alkaline.
- The nature of the soil itself can affect its acidity. Sandy soil has a lower concentration of organic matter, so it’s more likely to be acidic. Clay soil, on the other hand, is more alkaline because it contains a higher concentration of organic matter.
- Land use and management will also affect the soil pH. Forestland is more likely to be acidic, and transforming this land into grassland will increase the pH level. These changes lead to the removal of nutrients when the crops are harvested.
Soil with a pH level that is too low or too high can affect the plants’ health. When the pH level is too high in alkaline soil, the plants won’t be able to absorb the nutrients. When the pH level is too low in acidic soil, the nutrients will be overly absorbed, which overloads the plant’s systems.
Products to Increase the Soil pH
The pH level of the soil can be altered by several different products. If the soil is too acidic, it will be more subject to erosion, have a lower concentration of the helpful bacteria that improves plant growth, and decrease the amount of nutrients available for plants to thrive. Nevertheless, there are several products that you can use to fix highly acidic soil and increase its pH level.
Limestone
There are four types of limestone that can be used to change the soil’s acidity level, and you can expect the pH level to rise over the course of 2 to 3 months. The finer the lime, the faster the effect will be. Limestone is usually the fastest method to increase the soil’s pH level.
Pulverized lime is easy to apply and takes moderate time to show an effect. Granular and pelletized types can be mixed with fertilizer, while hydrated lime should be used only when the soil is highly acidic and delivers a faster effect. Lime should be used at least 2 or 3 months prior to the planting season, ideally during the fall or winter.
Potassium Carbonate
Potassium Carbonate can reach the root system faster, so it’s used periodically to protect the soil from a change in the pH level. When mixed with irrigation water, Potassium Carbonate will also increase the percentage of potassium, which is an essential nutrient for potatoes and other vegetables.
Bone Meal
Bone meal will increase the level of calcium in the soil and will also increase its pH level in the long run. However, this solution won’t work if you need a quick fix and will only fix the ph level if the soil is slightly acidic.
For best results, bone meal should be mixed with other solutions to increase the pH level of the soil. On average, 5 pounds of bone meal can be used per 50 square feet of garden.
Ground Clamshells
Grinding clamshells into fine powder will help elevate the pH level in acidic soil and also increase the level of calcium. However, too much calcium can affect the absorption of magnesium, so you can add Epsom salt to neutralize its effect.
Ground Eggshells
Just like clamshells, eggshells can be ground to increase the pH level. The finer the ground, the better the results will be.
The increased level of calcium will protect your plants if they suffer from blossom end rot or any other condition that is related to calcium deficiency. Ground eggshells don’t represent a fast remedy, but they also won’t harm your plants.
Ground Oyster Shells
Ground oyster shells represent a rich source of phosphorus and calcium. Therefore, oyster shells should be finely ground to facilitate absorption and raise the pH level of the soil slowly over time.
Oyster shells are sometimes used instead of lime because they can be used all year long, unlike lime which should be used only in winter. The shells also filter the water, so they will protect your plants from toxins.
Hardwood Ashes
Wood ashes contain high amounts of calcium and potassium, so they will enrich the soil with nutrients, and at the same time, they will increase the soil’s pH level. Ashes are rich in some elements like phosphorus and boron, but they’re not as fast as limestone if you need to fix the soil’s acidity rapidly.
One thing to note is that hardwood ashes shouldn’t come into contact with germinating seeds or the roots of growing plants as they might cause damage. Therefore, ashes should be used sparingly and only in winter or spring.
Products to Decrease the Soil pH
Some types of ornamental plants, flowers, and berries need to grow in slightly acidic soil. If these plants grow in alkaline soil, they’re likely to develop iron chlorosis, which causes plant leaves to yellow. If this is the case, there are several products that you can use to decrease the pH level if the soil is alkaline.
Aged Sawdust
Sawdust is rich in fibers that provide the roots of plants with necessary nutrients. However, sawdust should be used in tiny amounts and mixed with green waste to decrease the pH level. Otherwise, it will absorb all the nitrogen from the soil, and plants won’t be able to grow for a long time.
Mixing aged sawdust with nitrogen-rich material and turning the soil regularly will lead to better results. Sawdust takes a few years to break down, but it will safely decrease the pH level of your lawn in the long run.
Wood Chips
Just like sawdust, wood chips are rich in carbon and need access to nitrogen to decompose fully, and this means that your soil won’t have healthy nitrogen levels for a year or two. Nevertheless, if your soil is highly alkaline, wood chips can work as a remedy that gradually and safely decreases the pH level.
Wood chips should be mixed with green material like grass clippings or manure to help them break down faster in the soil. Ideally, you should turn the pile every month or so, and your soil’s pH level will be adjusted in a year or two.
Leaf Mold
Leaf mold is made of partially decomposed shredded leaves, and the leaves are usually acidic. Leaf mold has the capacity to hold 500% of its weight in water, so it will help retain the moisture level in the soil. It helps to moderate the pH level of the soil and helps neutralize it if it’s highly alkaline.
It’s best to keep leaf mold away from the base of the plant for pest control. However, it’s safe to use around vegetables and flowers.
Peat Moss
Peat moss is harvested from peat bogs and is commonly used in soilless mixes where the young roots of the plants are unable to push through. It’s lightweight and affordable, so it can be used both in indoor pots as well as in the garden.
Although peat moss can efficiently decrease the soil’s pH level, it’s not very sustainable because it takes hundreds of years to form. Moreover, it doesn’t add any nutritional value to the soil.
Cottonseed Meal
Cottonseed meal is used as a fertilizer if you’re growing acid-loving plants or if the soil is highly alkaline. It helps aerate dense soil and retains moisture in sandy soil. Additionally, cottonseed meal adds nitrogen and phosphorus to the plants, and is often mixed with bone meal if the soil has poor quality.
Pine Needles
Pine needles add a lot of nutrients to the soil and are used in compost or mulch to decrease the pH level. Just like other types of organic matter, pine needles improve soil aeration and drainage. You can mix pine needles with mulch and apply it to your soil.
Coffee Grounds
Coffee grounds are used in compost or applied directly as a fertilizer to provide the soil with nutrients. Coffee grounds gradually improve the aeration and drainage of the soil while adding the needed nitrogen. The grounds also attract earthworms and provide other organisms with the required nutrients.
Unwashed coffee grounds will help decrease the soil pH level because they’re acidic. Used coffee grounds are neutral, but they will provide the plants with the needed nutrients.
Fresh Manure
Manure is rich in fresh organic matter that adds a lot of benefits to the soil. When added, fresh manure can help loosen clay soil and tighten sandy soil, as well as adding nitrogen.
As manure decomposes in the soil, it forms humus, which attaches to the soil particles and changes the overall structure of the soil. At the same time, it gradually decreases the pH level, so it will work if your soil is alkaline. Only small amounts are needed, as the high concentration of salt and ammonia can burn the roots of new plants.
Oak Leaves and Bark
Although oak leaves are slightly acidic when they first break, they tend to become more alkaline after a while. Therefore, leaves should be chopped up and added directly to the soil or mixed with mulch.
Adding oak bark to mulch will also keep the soil’s temperature stable and reduce erosion. The bark should be applied regularly because it breaks down over time.
How to Alter Soil pH Level
Calculating the pH level of the soil is essential for the health of your plants. It will also help you decide on the products to use to modify it.
Test the Soil
You need to evaluate the soil by identifying its type and condition. Compact clay soil is usually more challenging to alter, while well-drained soil will be easier. You can buy a commercial test to calculate the pH level and accordingly determine the best types of plants that can easily grow in this soil.
Determine Which Product to Use
Depending on the condition of the soil, you can determine the right product to use. In the case of acidic soil, there are several products to choose from, but limestone usually yields the fastest results. If you have alkaline soil, you can use leaf mold, coffee grounds, or peat moss, as well as any of the above mentioned products. You can also wood chips or aged sawdust if you want to alter the soil’s pH level over an extended time period.
Mix Product Into the Soil
Depending on the product you’ve chosen, you can either apply the product directly and mix it with the soil or mix it with mulch.
Check the Water
The water you’re using can also have an impact on the soil’s pH level. Groundwater is more alkaline, while rainwater can be more acidic. So you need to water the plants and allow the materials to alter the pH level.
Test pH After Few Months
Use another test to check the pH level after a few months. Some methods like limestone can work within 2 to 3 months, while others like sawdust can take a couple of years to show results.
Conclusion
Different plants need various pH levels to grow. Some plants prefer acidic soil, while others prefer alkaline soil. Luckily, there are several products that you can use to alter the soil pH level and add more nutrients to keep all of your garden plants healthy and thriving.