Soil Science: Why Soil pH Matters

A map of the United States showing soil acidity levels, with varying percentages indicated by colors.

Lawnbright Labs has been digging in (pun intended!) to soil across the country for over two years, and we're ready to start sharing the results with the hopes of helping people understand what's going on beneath their feet. First topic: Soil Acidity, and how it robs fertilizers of their efficacy. 

If you live east of the Mississippi River, chances are you have acidic soil. This may not mean much to the average person, but understanding the crucial role of optimal pH in lawn care can make all the difference in your lawn. In this blog post, we delve into the importance of soil pH and how it can be the key to utilizing fertilizers efficiently for a thriving lawn.

The Impact of Acidic Soil on Fertilizer Efficiency

Soil pH is a measure of the soil's acidity or alkalinity and plays a fundamental role in nutrient availability to plants. The pH scale ranges from 1 to 14, with a pH of 7 being neutral. A pH below 7 indicates acidic soil, while a pH above 7 indicates alkaline soil. For lawns, the optimal pH range lies slightly acidic, between 6.0 and 7.0.

When soil becomes acidic, essential nutrients, such as nitrogen, phosphorus, and potassium, become less available to plants. As a result, the fertilizers applied to the lawn may not be effectively absorbed by the grass, leading to waste. The acidic environment can cause certain nutrients to leach away, becoming inaccessible to the grass roots and further exacerbating the problem.

fertilizer effectiveness corresponds to pH

Consequences of Fertilizer Waste

Fertilizer waste not only incurs unnecessary expenses but also poses environmental challenges. When excess fertilizer is left unused in the soil, it can leach into groundwater or runoff into nearby water bodies, causing water pollution. This can lead to algal blooms and can kill off aquatic ecosystems, creating a cascading effect on the environment.

The Role of Optimal pH in Fertilizer Absorption

Maintaining the correct soil pH is the key to unlocking the full potential of fertilizers and achieving a vibrant lawn. When the pH is within the optimal range of 6.0 to 7.0, several beneficial processes occur:

  1. Improved Nutrient Availability: In the slightly acidic pH range, crucial nutrients like nitrogen, phosphorus, and potassium are readily available for uptake by the grass roots. This enables the lawn to efficiently utilize the applied fertilizers.

  2. Enhanced Microbial Activity: Soil microorganisms that aid in nutrient recycling and decomposition thrive in the optimal pH range. These microorganisms break down organic matter, releasing nutrients for the grass to use effectively.

  3. Reduced Nutrient Loss: In the right pH conditions, the potential for nutrient leaching is minimized, as the soil can better retain essential elements for the plants to absorb.

  4. Healthier Grass Growth: Balanced pH promotes overall lawn health, making it more resilient to diseases, pests, and environmental stressors.

Most Lawn Soils Fall Outside the Optimal pH Range

Lawnbright has analyzed thousands of soil samples over the last two years, and has found 56% of lawn soils tested fall outside of the optimal pH range. Most that fall outside optimal range are on the alkaline side, but as you’ll see in a moment it doesn’t always require intervention to adjust the pH. As a side note, often calcium in these alkaline soils is "locked up” ie, unavailable to the plant. So many of these lawns still require an application of lime, even with a high pH. 

It’s important not to fight nature too hard. For example, soil in some regions have adapted to life a naturally alkaline environment. If your pH is slightly on the high side, don’t panic and try to lower it right away. You can waste a lot of time and effort (and quickly get yourself into trouble) trying to acidify soil that wants to sit slightly above the optimal range. 
Lawnbright’s soil analysis take pH into account, but do not pivot on a single pH metric when prescribing products. We build a composite picture, taking into account at the naturally occurring pH in your region, the deviation from the median, and other datapoints, to determine if pH altering products are needed.

Measuring Soil pH and Correcting Acidity

To determine the pH of your lawn's soil, a soil test is essential. Lawnbright sends test kits to every new customer in your first box. If the test reveals that your soil is too acidic, we deploy several methods to correct it:

  1. Liming: Adding agricultural lime to the soil can help raise pH levels over time. It is essential to follow the recommended application rates to avoid over-liming, which can lead to other nutrient imbalances.

  2. Increasing Organic Matter: Our bio-stimulants contain dense amounts of organic matter such as humic, molasses, and sea kelp, which can gradually improve soil pH and nutrient retention.

  3. pH-Adjusted Fertilizers: Our fertilizers are formulated to address specific pH issues based on the outcome of soil tests. Using pH-adjusted fertilizers can be beneficial for acidic soil conditions.

Optimal pH is the secret to unlocking your lawns full potential. By understanding how acidic soil affects fertilizer efficiency and the importance of maintaining the right pH range, you can avoid wasting fertilizer, and promote a vibrant and healthy lawn. 

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2 comments

Last year I spent $100 for a soil test kit (that included a special tool for digging up soil for the test). I couldn’t understand the results because I don’t have a PhD in botany, or physics. Imagine my surprise when I signed up for the subscription plan and got a FREE soil test kit, used a spoon to collect the dirt, and I can easily read the result. I’m a new customer and am happy to know that the products in my plan will be chosen specifically for the soil needs of my yard.

Terry W

Last year I spent $100 for a soil test kit (that included a special tool for digging up soil for the test). I couldn’t understand the results because I don’t have a PhD in botany, or physics. Imagine my surprise when I signed up for the subscription plan and got a FREE soil test kit, used a spoon to collect the dirt, and I can easily read the result. I’m a new customer and am happy to know that the products in my plan will be chosen specifically for the soil needs of my yard.

Terry W

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