The importance of monitoring soil pH in a vegetable garden
Healthy vegetable gardens depend on soil acidity. While not maintaining the optimal pH won’t necessarily ruin your vegetable crops, it can impact growth and crop quality. If you’ve ever experienced disappointing crops, this could be why.
What is soil pH?
Before we explore the importance of monitoring soil pH in a vegetable garden, let’s cover what soil pH is. Soil pH refers to the acidity or alkalinity (basicity) of soil. This is measured on the logarithmic pH scale, which ranges from 1 to 14.
The pH scale is typically displayed on a colour chart, with red for acidic values and purple/blue for alkaline values. The pH value refers to the concentration of hydrogen ions (pH stands for the potential of hydrogen). The higher the pH value (alkaline), the lower the hydrogen ion concentration.
On the logarithmic scale, the number indicates acidity. The lower the number, the stronger the acidic content and concentration of hydrogen ions. In contrast, the higher the number, the stronger the basicity and the lower the concentration of hydrogen ions. 7 in the middle is neutral.
The three soil pH classifications are as follows:
- - 0 to 6.5 is acidic (anything less than 5.5 is strongly acidic).
- - 6.5 to 7.5 is neutral.
- - 7.5 to 14 is alkaline (anything above 11 is a strong alkaline).
The average and optimal soil recommended for most gardens and vegetables is between 6.5 and 8. Here is the pH scale with examples for each of the different pH levels:
What affects soil pH in vegetable gardens?
Garden soil pH is typically determined based on the rocks that formed the soil alongside any weathering processes. However, there are some factors, particularly in vegetable gardens, that can change the pH of soil, including:
- - Root respiration
- - Plant growth
- - Fertiliser
- - Addition of minerals to the soil
- - Water flow
Some of these methods, such as using fertiliser, vegetable growth, and decomposition of organic components, are the biggest factors that alter soil pH levels in a vegetable garden. While crop rotation can reduce this, monitoring soil pH is necessary for improving crop growth.
Why should you monitor soil pH in a vegetable garden?
You should monitor soil pH in a vegetable garden for several reasons. From nutrient availability to microorganism activity, here are the most important reasons why monitoring and managing your vegetable garden’s soil pH is important.
Nutrient availability
Anyone with a vegetable garden, or considering starting one, should carefully monitor the soil pH, as it can affect nutrient availability and chemical solubility. As a result, this affects the macronutrients and micronutrients that your vegetable crops can absorb.
However, most essential nutrients your vegetable crops require are readily absorbent at the neutral pH range between 6.5 and 8. Fourteen of the total seventeen nutrients plants need are available at the optimal pH range.
Plant nutrition is one of the most important factors affecting plant growth, alongside water and sunlight for photosynthesis. Limiting these nutrients' availability can significantly impact your vegetables' growth potential.
The graphic below outlines the nutrients in your vegetable garden depending on the soil pH level. The green colouring indicates that the mineral is strongly available and absorbent at the given pH reading, whereas amber is the opposite.
Microorganism activity
Another reason to monitor soil pH in vegetable gardens is its effect on microorganism activity. Microbial activity refers to the microbiological processes that take place in the soil. Vegetable growth is heavily reliant on this activity.
That’s because micrograms play a vital role in organic nutrient mineralisation. Microorganisms require an optimal pH to work effectively for microbial processes. Such processes are essential for maintaining healthy soil that can affect vegetable crop growth.
Most soil bacteria (or neutrophiles) work optimally at the pH range between 6 and 8 (around the neutral range). Soil microorganisms refer to various microbes, including bacteria, fungi, algae, actinomycetes, protozoa, and nematodes.
A diverse microorganism content in the soil can significantly impact the effectiveness of microbial activity. The soil pH significantly impacts the diversity of microorganisms in the soil. A neutral range helps promote diverse microorganism activity in the soil.
Protection from diseases
Like ordinary garden plants, many vegetable plants can also suffer from diseases. These diseases are detrimental to your vegetable garden and can be harmful to eat. Plant pathogens are not harmful to humans in most cases, although fungal or moulding crops can be dangerous.
This is another reason to monitor your soil pH for vegetable gardens. That’s because plants growing in an optimal soil pH build up better resistance to plant diseases. An optimal pH level increases plants’ natural disease resistance alongside sufficient sunlight, nutrients, and water.
A soil acidity level that is too high or low can increase your vegetable crops' vulnerability to diseases. Monitoring and maintaining an optimal pH level also ensures nutrient availability, which helps vegetables gain extra resistance to diseases.
Maintaining an optimal soil pH is essential because many diseases can harm your vegetable crops. Diseases such as powdery mildew, mosaic virus, leaf spot, clubroot, and fusarium are the most common diseases that you can build resistance to with your vegetables with an optimal pH.
How do you test soil acidity?
If you are planning on starting a vegetable garden or are disappointed with previous crop growth, it may be time to test the acidity of your soil. Fortunately, there are a few ways you can test soil pH:
Soil pH meters
A
soil pH meter is the easiest way to measure soil pH levels. Providing accurate results, soil pH is the best way to determine your soil acidity precisely for home vegetable gardens. To use the device, all that’s required is to insert the probes into the soil and switch them on.
Some meters, such as the
EL-SM-METER3IN1, will also provide you with light and moisture readings. This allows you to determine whether vegetables are receiving enough water and sunlight necessary for photosynthesis.
pH test kits
Another method for testing soil pH is pH test kits. This method requires a little bit more chemistry, and you must use a testing solution to get a rough estimate of the acidity level. A small soil sample free from debris is necessary from around 6-8 inches below the surface level.
The soil sample is mixed with the testing solution. After shaking, you match the colour of the solution against the provided colour chart (pH scale). The only downside to this method is that a representative soil sample is required (free from fertilisers, dirt, and debris) and is only a rough estimate.
Litmus paper
The other method to monitor soil pH is litmus paper. This method is similar to pH test kits but uses litmus paper instead of a testing solution. In the same way, the litmus paper is dipped into a mixture of soil and water.
The litmus paper's colour change depends on the soil's pH level. The colour is then matched against the pH colour chart for a rough estimate of soil acidity. Again, this requires a representative soil sample and is only a rough estimate.
Soil pH plays a significant impact in ensuring healthy and blooming vegetable crops. Whether new to setting up a vegetable garden or regularly growing your own, monitoring soil pH is extremely important. By investing in a suitable testing method and taking corrective action, you can benefit from better, stronger, and bigger vegetable crops.