How To Fix Alkaline Soil-Best Practices

how to fix alkaline soil

What Is Alkaline Soil?

Have you recently discovered that your soil has turned alkaline? This might be something you need to look into. Alkaline soil is possibly harmful to the growth and quality of your plants.

Alkaline soil is known to stunt the growth of plants and cause nutrition deficiency. While a little alkaline soil might be beneficial for some plants, soil pH higher than 9 is considered harmful.

Soil pH value that is greater than 7 is deemed alkaline soil. A pH scale is divided from 1 to 14. Here, 1 is the most acidic, 7 is neutral, and 14 is the most alkaline. Alkaline soil falls between the pH value of 7 and 14 on the pH scale. A lot of farmers call such soil ‘sweet soil’.

Alkaline soils are less soluble than acidic soil. The levels of sodium, magnesium, and calcium are also high in alkaline soils. Water and plant nutrients also have a tough time penetrating alkaline soil and don’t get absorbed by plant roots.

This is harmful to plant health and often leads to stunted growth.

In soils with high pH value, nutrients such as iron, phosphorous, and manganese are in low quantities. This, too, affects the nutrition of plants. Some plants, such as asparagus, grow well in a high pH value soil, but that isn’t the norm for many plants. Most plants grow best in 7.5 ph soil.

There are many different ways of doing a soil test without visiting a soil laboratory. A simple way of soil testing is using cider vinegar. Put a few drops of cider vinegar on the soil sample. If it fizzes, then your soil pH is alkaline in nature.

This is the simplest and easiest way of getting soil test results, especially for garden soil.

What Makes Soil Alkaline?

There are many reasons for soil alkalinity. Humans, as well as nature, are responsible for increasing the pH value of soils. Let’s discuss these.

Natural Minerals

Soil minerals that produce sodium bicarbonate and sodium carbonate cause alkalinity in the soil. All these by-products are produced upon weathering. Weathering is the process of breaking down rocks upon contact with rain, gases, and biological organisms.

These compounds produced by soil minerals are alkaline in nature and increase soil pH values to make them more alkaline.


Alkaline soil is commonly found in desert regions or land that is arid. Areas that receive regular rainfall and are densely forested usually have acid in their soils. The absence of hydration in desert regions makes soil texture dry.

If there isn’t enough water content to leach the soluble salts of soils, the accumulation of alkalinity occurs. Soil moisture is important in leaching these salts.

This is due to compounds like calcium carbonate and sodium carbonate being formed. These compounds increase soil pH and make it more alkaline.

Soft Water Irrigation

Irrigation is an important step in growing crops and plants. Almost everything, whether large farms or garden soil, needs some form of irrigation. Irrigation is the process of providing water to your crops and plants through an artificial process. It also helps improve water retention and absorption of nutrients.

Irrigation is beneficial in places where rain is scarce and unreliable. A lot of farmers use soft water for irrigation purposes. This is responsible for soil alkalinity as it has a relatively high level of sodium bicarbonate and lower levels of magnesium and calcium. It increases the soil pH value.


Liming is the process of adding calcium and magnesium minerals in various forms. These can be ground limestone, chalk, marl, burnt lime, or hydrated lime. Liming helps in better absorption of nutrients and helps in plant growth. Liming is almost universally done to all plants.

Liming also increases soil’s pH values and is used if the acidity of the soil is too high. This is because lime causes the soil pH to rise, making it alkaline. Thus, over-liming or using excessive lime can cause soil to become alkaline and increase pH levels.

Tips On How To Fixing Alkaline Soil

There are many ways to lower soil pH values. Let’s discuss some of these.

Add Sulphur To Soil

One of the best ways to reduce the alkaline nature of the soil is by adding sulfur. Adding about 1-3 grams of ground rock sulfur to 9 square feet (1 square yard) can reduce soil pH by one.

Soil bacteria convert sulfur into sulfuric acid, which helps reduce the pH level. Compounds such as iron sulfate and aluminum sulfate can also help reduce the alkalinity of the soil. You can also use elemental sulfur (soil sulfur) to reduce the pH of your soil.

This method is extensively used for farming blueberries.


Fertilizers that use an acidifying nitrogen source are used to increase the soil pH levels. Ammonia or urea-based fertilizers are an excellent way of reducing soil pH. These kinds of acidifying fertilizers contain ammonium sulfate, diammonium, and mono ammonium phosphate.

This ammonium from the fertilizers oxidizes to form formed nitric acid. Nitric acid is when the nitrogen oxide is oxidized into nitrogen dioxide, which H2O then absorbs. Nitric acid helps reduce soil pH, thus reducing its alkaline nature.

It is recommended that you don’t use more than 5 pounds of acidifying fertilizer forever 100 square feet.


Composting is the process of recycling organic matter and using it as fertilizer. Composting is an excellent way of ensuring your plants get the necessary plant nutrients organically from soils. It also improves soil structure and provides beneficial micro-organisms. Composting has increasingly become popular in vegetable gardens.

You can make your compost acidic by using acidic materials. You can also increase acidity by adding some aluminum sulfate. The organic matter in compost helps balance soil pH levels. If the soil pH level indicates acidity or alkalinity, compost helps bring the level closer to neutral.

Plants That Fix Soil pH

There are a few plants that help reduce the pH of soils. They are also the best organic way of doing so. Here are a few of the best plants to reduce the pH of your soil.

Sphagnum Peat Moss

Sphagnum peat moss is a natural amendment that can be added to the soil. This kind of moss helps reduce the pH level of the soil. Plants such as rhododendrons and azaleas are acid-loving plants and thrive at lower pH levels. These plants don’t grow well in alkaline soils.

Thus, many people use sphagnum peat moss along with their soil to lower the pH value for such plants. Such remedies are easy to execute in garden areas.

Pine Needles, Oak Leaves, And Coffee Grounds

Some of the best materials to make compost more acidic are pine needles, oak leaves, and coffee grounds. These kinds of organic matter help reduce the pH of soils.

Materials like wood ash should not be used for composting as they increase the pH of the soil and make it more alkaline.

Final Thoughts

Alkaline soil is caused due higher than 7 pH soil. The reasons can be completely natural, like low rainfall, or man-made, like over-liming.

There are multiple ways, both natural and chemical, to fix the pH of your soil. It is recommended that you choose the option that is best for you and your purposes. Some of the easiest ways are composting and using sphagnum moss.