This Is How Farmers Reduce Acidity in the Soil

Farmers face a litany of challenges every day, but one of the most crucial issues facing those in the agricultural industry is acidic soil. Highly acidic soil can be a nightmare, as crops may struggle to grow in soil with a low pH. How do farmers reduce soil acidity?

Farmers reduce acidity in the soil by applying sodium bicarbonate, agricultural lime, or wood ashes. These substances are alkaline, which helps increase the pH of the soil to neutral levels. This is an important process, as highly acidic soil can affect plant growth and increase erosion.

This article will explore how farmers correct pH imbalances in soil and discuss the factors contributing to soil acidity. We’ll also reveal ways gardeners can reduce soil acidity and make sure their gardens flourish.

How Farmers Reduce Acidity in the Soil

There are more than 2 million farms in the United States, and each faces constant challenges. Low crop yields, prolonged droughts, and outdated equipment are common issues, but acidic soil is a far more insidious danger.

Soil becomes more acidic the closer it is to a pH of 1. Most plants prefer soil with a slightly acidic to neutral pH of 6 or 7. When soil pH falls below this point, plants will fail to thrive, resulting in dead crops and mounting business debts. 

Luckily, there are two tried-and-true ways farmers can reduce acidity in the soil:

  • Adding substances to make the soil more alkaline
  • Preventing soil acidification by implementing operational changes

Let’s discuss both methods to discover how farmers combat acidic soil:

Adding Substances to Make the Soil More Alkaline

It can be almost impossible to grow healthy crops in extremely acidic soil. This is why farmers may need to quickly add alkaline substances to lower the pH of the soil if it ever becomes too acidic. 

There are three main substances farmers use to reduce acidity in the soil:

  • Agricultural lime
  • Wood ash
  • Sodium bicarbonate

While these aren’t the only alkaline substances that mix well with soil, they are widely available from agricultural suppliers throughout the United States. These substances are also far more affordable than synthetic pH-changing chemicals, especially when purchased in bulk.

Agricultural Lime

Commercial farms can generate above-average incomes for their owners, but smaller farms tend to run on a constant deficit. Consequently, choosing low-cost supplies is crucial to keeping farms operational.

One of the most affordable remedies for acidic soil is agricultural lime.

Agricultural lime (calcium carbonate) is the most common alkaline substance farmers use to raise soil pH. That’s because agricultural lime is comparatively low-cost, readily available from most agricultural supply stores, and effective.

Agricultural lime reduces acidity in the soil by changing aluminum and magnesium—two substances that contribute to acidification—in the soil into insoluble substances. This means these elements cannot break down in the soil to produce acids.

Farmers can purchase a 50 lb (22.68 kg) bag of calcium carbonate for about half the price of a same-sized bag of baking soda. It typically costs less than $500 to cover an acre (0.4 hectares) of land with agricultural lime, making it the most cost-effective solution to soil acidification. 

Wood Ash

Those with small farms or organic crops may prefer to use wood ash to lower soil acidity levels and raise pH.

Wood ash is generally the most expensive alkaline substance available to farmers. As such, it’s not used as often as agricultural lime or baking soda. However, wood ash is extremely effective and jam-packed with life-sustaining nutrients. 

Farmers can replenish nutrient-poor soil while also balancing pH by spreading small amounts of wood ash over their fields, typically by adding it to the water in field irrigation systems.

Too much wood ash can cause soil to become highly alkaline. Luckily, little goes a long way. 

Some farmers may be willing to pay a higher price for wood ash to reduce their workload while also creating a balance between soil nutrients and pH. Of course, those hoping to raise soil pH without introducing nutrients will almost always opt for baking soda.

Sodium Bicarbonate

Sodium bicarbonate (better known as baking soda) has a pH of 8, making it slightly alkaline. It’s far less expensive than wood ash but pricier than agricultural lime. 

For example, a 50 lb (22.7 kg) bag of baking soda from a local agricultural supply store typically costs less than $40. To cover an acre (0.4 hectares) of arable land, you’d need approximately 200 bags. That raises the total cost of raising soil pH using baking soda to just under $7,000.

Using baking soda to correct soil pH levels is more than 10x pricier than using agricultural lime. That said, baking soda doesn’t increase calcium or magnesium levels in the soil, while calcium carbonate (the main component in agricultural lime) does. 

This means baking soda is less likely to imbue soil with an overabundance of these nutrients, making it generally safer. Additionally, baking soda can inhibit fungal growth in the soil, reducing the risk of crops developing mold and fungal infections.

Farmers who use baking soda on their fields typically add the substance to their field irrigation systems for a homogeneous application that’s quickly absorbed into the soil.

How Farmers Prevent Soil Acidification

In addition to amending the soil with alkaline substances, farmers also take precautions to help stop further acidification of the soil. Doing so reduces the required application rate and quantity of alkaline substances required to maintain the desired soil pH.

Some of the most common ways farmers prevent soil acidification include:

  • Not using nitrogen fertilizers
  • Avoiding adding gypsum to the soil
  • Removing granite stones from tilled fields
  • Adding animal manure fertilizer to the soil

But how do each of these practices help keep the soil within a neutral PH?

Avoiding Nitrogen Fertilizers

Several types of crops require high levels of nitrogen to produce fruit.

Some of the most nitrogen-heavy vegetables include:

  • Broccoli
  • Cabbage
  • Potatoes
  • Spinach

Because there’s a high demand for these vegetables, they’re a common cash crop. But to ensure a high return on these crops, farmers must ensure that their prepared fields are nitrogen-rich, which is why farmers might apply nitrogen fertilizers before seeding.

While nitrogen fertilizers can dramatically increase nitrogen levels in the soil, they can also contribute to soil acidification. That’s because several types of nitrogen fertilizers contain ammonium.

This substance turns into nitrate in the soil, producing nitrogen gas. This gas can make the soil more acidic, especially when crops cannot consume the amount of nitrogen produced. 

To remedy this issue, farmers must either not apply nitrogen fertilizers or use them cautiously. However, nitrogen-based fertilizers aren’t the only common agricultural products that contribute to acidity in the soil. 

Avoiding Gypsum

Gypsum (calcium sulfate) is considered a liming agent. But unlike agricultural lime or dolomite lime, gypsum doesn’t raise soil pH. Instead, this substance can make the soil more acidic over time.

That’s because gypsum contains sulfur. While most crop plants need small amounts of sulfur, the sulfur released into the soil after adding gypsum can result in a nutrient imbalance. In fact, sulfur (most commonly elemental sulfur) is used to lower soil pH.

Due to gypsum’s high calcium content, many farmers apply gypsum-based fertilizers to their fields after crop harvests. After all, spinach and soybeans can strip the land of its natural calcium deposits, making it challenging for farmers to regrow those crops in later seasons.

Agricultural lime is a far better way to add calcium to the soil, especially when the soil is highly acidic. Instead of releasing sulfur, agricultural lime releases calcium and magnesium, helping to replenish soil nutrients while balancing pH levels safely.

Removing Granite Rocks

Granite is a type of acidic igneous rock. It’s commonly found in states like Texas, Wisconsin, and Georgia. While this rock is useful for several industrial and commercial applications, it can be a nightmare for farmers.

Not only can thick granite chunks damage tilling machinery, but they can also contribute to the acidification of arable soil. Though granite degrades very slowly due to its high density, it’s a porous material.

Water or rain passing through granite stones can carry acids into the soil. Over time, this process can take the soil’s pH to extremely low levels, causing life-sustaining nutrients to sink below the topsoil. 

When this happens, crops may be unable to access those nutrients, causing them to die en masse. This is why farmers must remove granite from their fields or double their investment in alkaline substances to counteract the effects of local granite supplies on soil pH.

Adding Animal Manure

Though plant-based compost is much more affordable and easier to come by than animal-based compost, it can contribute to soil acidification. 

When organic matter decomposes and turns into compost, it releases carbon dioxide. While most of this gas enters the air, some of it can leach into the soil, becoming carbonic acid. This process lowers soil pH, resulting in a highly acidic environment.  

Adding animal manure can offset this acidification, as manure is typically alkaline. Manure can also encourage beneficial soilborne organisms like earthworms and microbes to reproduce and spread throughout the soil.

Soil acidification can kill these beneficial organisms, many of which are crucial to soil pore formation. Adding animal manure to tilled fields to prepare for the upcoming planting season is a common practice among farmers, especially those battling acidity in the soil.

How Gardeners Can Reduce Soil Acidity

While some plants (like blueberries) prefer acidic soil, most thrive when grown in soil with a neutral pH. So, if you test your garden soil and it shows a pH lower than 6, you’ll likely want to amend it.

Fortunately, home gardeners can use several of the same amendment substances as farmers!

That said, those growing container or backyard gardens likely won’t want to order bulk amounts of these, which is why it might be best to simply:

  • Add baking soda to your soil.
  • Spread garden lime over your soil.
  • Avoid using acidic fertilizer.

Let’s discuss how to use each of these methods to increase your soil’s pH and decrease its acidity:

Add Baking Soda to Your Soil

Small farmers often use baking soda to alter the pH of their tilled fields, and you can do the same. Adding baking soda to your soil is a straightforward process, and baking soda is generally more affordable than fertilizer or garden lime.

You’ll need to use one tablespoon (14.4 g) of baking soda per gallon (3.8 liters) of water you spray onto the soil. To make things simple, add a tablespoon (14.4 g) of baking soda to a one-gallon (3.8 liters) watering can, fill the container, and get to work!

Depending on the size of your garden and the soil’s acidity, you may need to use a few tablespoons or a few pounds of baking soda to adjust the soil pH. Consider purchasing a significant supply of baking soda to reduce repeat trips to your local grocery store.

Not only is baking soda a useful substance for raising your soil’s pH, but it’s also excellent at removing stains, smells, and greasy messes around your home.

Spread Garden Lime Over Your Soil

If you’d prefer to keep your baking soda in the pantry, you can use calcium carbonate (garden lime) to raise your soil’s pH. This white powdery substance is also the most popular soil amendment farmers use to reverse soil acidification.

Depending on the type of garden lime you choose, you’ll either need to mix the lime into the soil using a twist aerator or mix the lime with water and pour the mixture onto your garden beds. 

Garden lime is available from most garden centers and home improvement stores. If you have questions about how to apply this substance, be sure to ask store staff before making a purchase.

The best time to amend soil is before planting, though you can briefly unearth plants to lower soil pH in the middle of the growing season. Still, if possible, apply garden lime after the last frost but before the spring season begins.

Avoid Using Acidic Fertilizers

Every plant has different pH and nutritional requirements. You can run a comprehensive soil test to determine what nutrients are lacking in the soil or whether or not it needs a pH-altering amendment.

Since many plants thrive in slightly acidic to neutral pH, a small amount of acidic fertilizers like aluminum sulfate or ammonium sulfate shouldn’t be a big issue. However, if your garden soil is already acidic, you may need to avoid using them and find suitable alternatives.

For instance, if your soil needs nitrogen, you can use ammonium nitrate, which is less acidic than ammonium sulfate. Alternatively, you can use calcium nitrate, which is more alkaline.

Better yet, you can use acidic fertilizers locally or only around target plants that require lower soil pH, such as blueberries and azaleas.

Final Thoughts

Soil acidity can cause soil erosion, make plants grow slowly (or not at all), and kill beneficial organisms that live in topsoil. That’s why farmers use multiple methods to reduce acidity in the soil.

Many farmers in North America use agricultural lime and wood ashes to raise soil pH levels to a neutral point. These substances can be more challenging for home gardeners to access, but alternatives like baking soda and garden lime can help make garden soil more alkaline.

Removing and reducing acidic elements, such as sulfate and nitrogen fertilizers, can also reduce soil acidity.

Alexander Picot

Alexander Picot is the founder of and its lead content writer. He created the website in 2022 as a resource for horticulture lovers and beginners alike, compiling all the gardening tips he discovered over the years. Alex has a passion for caring for plants, turning backyards into feel-good places, and sharing his knowledge with the rest of the world.

Recent Posts