Why Does Soil Become Acidic? [Explained]

Soil acidity, also known as soil pH, refers to the level of acidity or basicity in soil. Soil can become acidic due to a variety of factors, including weathering of rocks and minerals, the decomposition of organic matter, and the application of acidifying fertilizers and other chemicals. The pH scale ranges from 0 to 14, with 7 being neutral, less than 7 being acidic, and greater than 7 is basic. Acidic soil can have a negative impact on plant growth and can also lead to nutrient deficiencies in plants.

What Does It Mean When Soil Is Acidic?

1. The pH scale: Soil acidity is measured on the pH scale, which ranges from 0 to 14. A pH of 7 is considered neutral, a pH below 7 is considered acidic, and a pH above 7 is considered basic.
2. Impact on plant growth: Acidic soil can have a negative impact on plant growth as it can make it difficult for plants to absorb essential nutrients such as phosphorus and potassium. This can lead to stunted growth and a lack of foliage.
3. Nutrient deficiencies: Plants grown in acidic soil may also suffer from nutrient deficiencies, as some elements like calcium, magnesium, and zinc are less available at lower pH values.
4. Altered microbial activity: The acidity of the soil affects the microbial activity, which can be beneficial or harmful to the plants. For instance, acidity may inhibit the growth of pathogens but also can inhibit the growth of beneficial microorganisms.
5. Altered soil structure: Soil acidity can also alter the structure of the soil, making it more compact and less porous, which can lead to poor drainage and poor aeration.
6. Altered soil chemistry: Acidic soil can alter the chemical composition of the soil, leading to increased levels of aluminum and manganese, which can be toxic to plants.
7. Altered soil biota: Acidic soil can affect the soil biota by killing off beneficial microorganisms and reducing the diversity of organisms in the soil, which can lead to a decline in soil fertility.
8. Altered water retention: Acidic soil can cause water retention issues as well, making it difficult for plants to absorb water and nutrients.
9. Altered soil color: Acidic soil can also change the color of the soil, making it appear yellow or red.
10. Altered soil temperature: acidic soil can retain more heat, which can be beneficial in cold climates but can be detrimental in warm climates.

Why Does Soil Become Acidic?

1. Weathering of rocks and minerals: Over time, rocks and minerals in the soil can weather and release acidic compounds, which can lower the pH of the soil.
2. Decomposition of organic matter: The decomposition of organic matter in the soil, such as leaves and plant debris, can also contribute to soil acidity. This is because the decomposition process releases organic acids into the soil.
3. Application of acidifying fertilizers: The use of acidifying fertilizers, such as ammonium sulfate, can also lower the pH of the soil.
4. Acid rain: Acid rain, caused by the release of sulfur dioxide and nitrogen oxides into the atmosphere, can also contribute to soil acidity as it falls to the ground and mixes with soil.
5. Industrial pollution: Industrial pollution and mining activities can also contribute to soil acidity by releasing acid-forming compounds into the soil and air.
6. Natural vegetation: Certain types of vegetation, such as pine and spruce trees, can also contribute to soil acidity by releasing acids into the soil through their needles and leaves.
7. Soil type: Some types of soil, such as sandy soils, are naturally more acidic than others and are more prone to becoming even more acidic over time.
8. Climate: Climate also plays a role in soil acidity. For example, areas with high rainfall tend to have more acidic soils than those with low rainfall.
9. Human activities: Human activities such as the overuse of fertilizers, overgrazing, and deforestation can also contribute to soil acidity.
10. Time: Soil acidity can also increase over time due to natural processes such as weathering, leaching, and decomposition.

What Happens When Soil Is Too Acidic?

1. Nutrient deficiencies: When soil is too acidic, it can make it difficult for plants to absorb essential nutrients such as phosphorus and potassium, leading to nutrient deficiencies and stunted growth.
2. Altered microbial activity: The acidity of the soil affects the microbial activity, which can be beneficial or harmful to the plants. For instance, acidity may inhibit the growth of pathogens but also can inhibit the growth of beneficial microorganisms.
3. Altered soil structure: Soil acidity can also alter the structure of the soil, making it more compact and less porous, which can lead to poor drainage and poor aeration.
4. Altered soil chemistry: Soil that is too acidic can alter the chemical composition of the soil, leading to increased levels of aluminum and manganese, which can be toxic to plants.
5. Altered soil biota: Soil that is too acidic can affect the soil biota by killing off beneficial microorganisms and reducing the diversity of organisms in the soil, which can lead to a decline in soil fertility.
6. Altered water retention: Soil that is too acidic can cause water retention issues as well, making it difficult for plants to absorb water and nutrients.
7. Altered soil color: Soil that is too acidic can also change the color of the soil, making it appear yellow or red.
8. Altered soil temperature: Soil that is too acidic can retain more heat, which can be beneficial in cold climates but can be detrimental in warm climates.
9. Reduced crop yields: Soil that is too acidic can also result in reduced crop yields and can make it difficult to grow certain types of plants.
10. Environmental impact: Soil that is too acidic can also have negative environmental impacts, such as reducing biodiversity and altering ecosystem processes.

How Do You Reduce Acidity In Soil Naturally?

1. Liming: One of the most common ways to reduce soil acidity is through liming, which involves adding lime (calcium carbonate) to the soil. Lime neutralizes acidity and raises the pH of the soil.
2. Organic matter: Adding organic matter such as compost, leaf mold, and well-rotted manure to the soil can also help to reduce acidity. The decomposition of organic matter releases basic compounds into the soil, which can help to neutralize acidity.
3. Green manure: Planting green manure crops such as clover, alfalfa, and rye can also help to reduce soil acidity. These crops take up acidic ions from the soil and release basic ions, which can help to neutralize acidity.
4. Gypsum: Gypsum is a natural source of calcium and sulfur that can also be added to soil to reduce acidity. It can also improve soil structure and water-holding capacity.
5. Wood ash: Wood ash, which is a byproduct of burning wood, is high in calcium and can be used as a soil amendment to reduce acidity.
6. Bacteria and Fungi: Adding beneficial bacteria and fungi such as mycorrhizae can help to neutralize acidity by breaking down organic matter.
7. Avoid acidifying fertilizers: Avoid the use of fertilizers that are known to acidify the soil, such as ammonium nitrate, ammonium sulfate, and urea.
8. Monitoring: Regularly monitor soil pH levels and keep records of pH test results. This way, you can monitor progress and adjust your approach accordingly.
9. Plant selection: Choose plants that are well-suited to acidic soils, such as azaleas, blueberries, and rhododendrons.
10. Avoid over-watering: Over-watering can also lead to acidity, so be mindful of how much water you’re giving your plants.

What do farmers add to reduce the acidity of the soil?

Farmers add a variety of materials to reduce the acidity of the soil, including:

1. Lime: Lime, which is made from calcium carbonate, is the most commonly used material for reducing soil acidity. Lime neutralizes acidity and raises the pH of the soil.
2. Dolomitic lime: Dolomitic lime is a type of lime that also contains magnesium, which can help to improve soil structure and fertility.
3. Agricultural lime: Agricultural lime is a finely ground limestone that can be easily spread on fields.
4. Hydrated lime: Hydrated lime is a powdery substance that is made by adding water to quicklime. It is more effective than agricultural lime in neutralizing acidity.
5. Marl: Marl is a type of sedimentary rock that is rich in calcium carbonate. It is used as a soil amendment in some areas to reduce acidity.
6. Calcitic lime: Calcitic lime is a type of lime that is made from calcium carbonate. It can be used in the same way as dolomitic lime.
7. Gypsum: Gypsum is a natural source of calcium and sulfur that can also be added to soil to reduce acidity. It can also improve soil structure and water-holding capacity.
8. Wood ash: Wood ash, which is a byproduct of burning wood, is high in calcium and can be used as a soil amendment to reduce acidity.
9. Organic matter: Adding organic matter such as compost, leaf mold, and well-rotted manure to the soil can also help to reduce acidity.
10. Bacteria and Fungi: Adding beneficial bacteria and fungi such as mycorrhizae can help to neutralize acidity by breaking down organic matter.
11. It is important to note that the best option for reducing soil acidity may vary depending on the specific soil conditions, crop requirements, and cost. It is always best to consult with a soil scientist or agronomist to determine the best course of action.

Do plants like acidic soil?

Not all plants prefer acidic soil. Some plants, such as blueberries, rhododendrons, and azaleas, are well-suited to acidic soils and are often referred to as “acid-loving” plants. 

These plants have adapted to thrive in soils with a pH range of 4.5-6.5. However, most plants prefer neutral to slightly acidic soil with a pH range of 6.0-7.0. 

When the soil is too acidic, it can make it difficult for plants to absorb essential nutrients, which can lead to stunted growth and nutrient deficiencies. This can happen when the soil pH is lower than 5.5. Some plants may struggle to grow in soil with pH levels lower than 5.0. 

Additionally, high levels of acidity can also lead to increased levels of aluminum and manganese, which can be toxic to plants. Therefore, it is important to understand the pH preferences of the specific plants you are growing and to test your soil to ensure it is within the correct pH range.

Does rain make the soil acidic?

Rainwater is generally considered to be slightly acidic, with a pH range of 5.5-6.5. The acidity of rainwater is caused by the presence of dissolved carbon dioxide, which forms carbonic acid. 

However, the acidity of rainwater alone is generally not enough to significantly affect the pH of soil.

However, acid rain, which is caused by the release of sulfur dioxide and nitrogen oxides into the atmosphere, can contribute to soil acidity. When acid rain falls to the ground, it can mix with soil, increasing its acidity and lowering the pH. 

Additionally, acid rain can also contribute to the leaching of basic minerals such as calcium, magnesium, and potassium from the soil, which can further acidify the soil.

It is also worth noting that the acidity of the soil can also be affected by other factors, such as the weathering of rocks and minerals, the decomposition of organic matter, and the application of acidifying fertilizers. Therefore, it’s important to consider all the possible factors that may be causing soil acidity and not only focus on the acidity of the rain.

Conclusion

In conclusion, soil acidity, also known as soil pH, refers to the level of acidity or basicity in soil. Soil can become acidic due to a variety of factors, including weathering of rocks and minerals, the decomposition of organic matter, and the application of acidifying fertilizers and other chemicals.

The pH scale ranges from 0 to 14, with 7 being neutral, less than 7 being acidic, and greater than 7 is basic. Acidic soil can have a negative impact on plant growth and can also lead to nutrient deficiencies in plants, altered microbial activity, altered soil structure, altered soil chemistry, altered soil biota, altered water retention, altered soil color, and altered soil temperature.

Farmers use lime and other materials to reduce the acidity of the soil. Rainwater is generally considered to be slightly acidic, with a pH range of 5.5-6.5. However, acid rain can contribute to soil acidity.

Plants have different pH preferences, and not all plants prefer acidic soil. It’s important to understand the pH preferences of the specific plants you are growing and to test your soil to ensure it is within the correct pH range.