Soil analysis: simple methods to understand the quality of your soil
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Time to read 11 min
Summary
Why analyze soil? Better cultivation: adapt inputs, prevent deficiencies. Identify problems: acidity, compaction, pollution. Guarantee soil sustainability (garden, crops, pasture, etc.). What are the methods for analyzing soil? Basic methods: visual observation, texture, smell, manual testing. Simple DIY chemical tests (kits available) . Laboratory analyses: precise and detailed results. Physicochemical, particle size, and biological analysis. How to test soil yourself? Necessary tools: spade, container, testers. Take a representative sample . Perform the tests: pH, texture, drainage, organic matter, etc. How do you know if the soil is good? 6 criteria for evaluating good soil. Analyzing your garden soil: a concrete example. Why should gardeners analyze their soil? Simple methods for individuals. When and how often should you analyze it? What to do after the analysis? Read the results of a test or laboratory report. Adapt your practices: amendments, fertilizers, soil rest… Repeat the analysis after a few months: follow-up. Frequently Asked Questions (FAQ). Why trust Pouryère for your soil analysis? To learn more
Why analyze soil?
Soil analysis can be carried out for several reasons.
Better cultivation: adapting inputs, preventing deficiencies
To better cultivate plants and trees, assessing soil fertility is fundamental. The soil's pH, its type (clay, sand, silt, or humus-rich), and its mineral content or underground burrows produced by earthworms are all factors that favor plant growth.
This will help you determine if your soil needs fertilizer and which types of plants will thrive best, depending on its composition. This type of analysis is suitable for amateur and professional gardeners, market gardeners, and farmers alike.
Identify the problems: acidity, compaction, pollution
Analyzing soil also allows us to detect certain problems that are not necessarily visible to the naked eye:
- Is the soil acidic? If so, earthworms are scarce and most nutrients cannot reach the plant for growth. It also promotes disease and the deposition of heavy metals like aluminum. Acidic soil has a pH below 5 or 5.5.
- Is the soil compacted? This phenomenon occurs particularly in agricultural fields that have been heavily tilled by tractors and machinery. The repeated passage of heavy equipment has compacted the soil, forming what is also called soil compaction or a plow pan. This can prevent any plant from growing properly.
- Is there pollution present? This could be heavy metals such as lead, iron or cadmium, but also PFAS, hydrocarbons or pesticides such as triazotes or triazines.
Ensuring soil sustainability (garden, crops, meadow…)
To ensure long-term soil health, analyze your soil to understand its specific characteristics and needs. By providing the right nutrients, planting appropriate tree and plant species, and working the soil correctly, you will maintain your garden or lawn in perfect condition with a harmonious ecosystem.
What are the methods for analyzing soil?
Basic methods: visual observation, texture, smell, manual testing
Even without the need for tools, visual observation of the soil can already provide a good overview. For example, yellowing or stunted plants, as well as areas where nothing grows, can indicate the presence of pollutants in the soil , such as heavy metals.
To assess soil texture, a particle size analysis is necessary. By taking a sample of soil and placing it in a jar of water, you perform a sedimentation test. If the grains are very small, less than 2 µm, you have clay soil. Between 2 µm and 50 µm, it's loamy soil, and between 50 µm and 2,000 µm, it's sandy soil.
Finally, the smell of the soil is also an indicator. Soil that gives off a forest floor scent is healthy. On the other hand, a rotten smell could be a sign of an excessive presence of mold or fungi.
Simple DIY chemical tests (kits available)
If you want to take your soil analysis further, you can purchase a chemical testing kit. Most garden centers sell pH tests with strips or more sophisticated devices, such as soil testers. For around twenty euros, you'll get data on the soil's pH, light levels, and moisture content. Other kits allow you to measure soil nutrient levels: nitrogen, phosphorus, potassium, etc.
These solutions are, however, quite superficial, especially since, for example, soil testers only carry out their analysis a few centimeters from the surface.
Laboratory analyses: precise and detailed results
Laboratory analysis is the most comprehensive solution for analyzing your soil in depth. This provides you with a detailed agronomic analysis: texture, particle size distribution, acid-base status (pH), organic and biological state, chemical balance, trace element content, etc.
In this context, you have two options:
- You can contact a specialist company that will send a technician to your location to take samples. These samples are then sent to a laboratory for analysis, and you will receive a detailed and explained report.
- Purchase a complete kit online. You collect the soil sample, but the analysis is done in a laboratory. This option provides a comprehensive diagnosis for a few hundred euros. Pouryère offers this service through its AGROKIT: a very thorough agronomic soil analysis for under 200 euros.
Physico-chemical, particle size analysis, biological analysis
For a high-performance physico-chemical analysis of the soil, three main factors are essential.
Type of analysis |
Items sought |
Indicators of healthy soil |
soil pH |
Soil acidity level: if it is less than 5 or 5.5, it is acidic. |
Ideally above 6.5. Below this, the soil is considered to need leveling, generally by adding lime. |
Particle size |
Soil grain size is used to define whether the soil is sandy, silty, or clayey. This is done using the soil texture triangle: a soil can have a single or multiple composition (sandy-silty, clayey-sandy, etc.). |
No single type of soil is better than another; each has its advantages and disadvantages. For example, clay soil is susceptible to ground movement but retains moisture and minerals well. Sandy soil is easy to work but retains little water and nutrients. |
Biological |
Biological analysis assesses, in particular, the presence of organic matter, its level, the depth and appearance of the roots, and the biological activity of the soil (presence of microorganisms, earthworms, etc.). |
Healthy soil has many microorganisms, abundant organic matter, and a dense root system that penetrates deep into the earth. |
How to test the soil yourself?
Without resorting to a professional, you can test the soil yourself with a few tools.
Tools needed: spade, container, testers
A spade will be useful for removing soil from your plot. Also, have a container ready to store it, as well as a jar of water for the sedimentation test. Finally, purchase commercially available testers, such as a pH tester or a test kit that combines several elements: pH, moisture, soil temperature, etc.
Take a representative sample
To obtain a representative sample of your soil, collect soil from several locations: in your vegetable garden, under a tree, in an open field, near your compost heap, etc. Carry out this task under suitable conditions. Avoid periods of frost, drought, or flooding. Soil that is too hard or waterlogged will not give results that accurately reflect reality.
To obtain a usable sample, remove any leaves, decaying leaves, branches, twigs, and other small stones. However, leave any small roots and naturally occurring microorganisms. Place the sample in a resealable bag, such as a zip-top freezer bag.
Perform the tests: pH, texture, drainage, organic matter…
Next comes the time to perform the tests for your soil analysis. For pH, use test strips or a soil tester. For particle size analysis, carry out a sedimentation test, which will reveal the nature of your soil: clay, silt, sand, or humus-rich. Finally, some test kits can detect the presence of chemical compounds beneficial to plant growth, such as phosphorus, nitrogen, or potassium. These are the three major soil elements: if they are present in insufficient quantities, your plants may not thrive.
How can you tell if the soil is good?
Good soil displays specific characteristics, particularly in terms of smell, color, water circulation, and the presence of organic life: earthworms and mycorrhizae.
6 criteria for evaluating good soil
1- A lumpy structure
Soil with a crumbly texture is rich in humus, well-aerated, and has abundant root systems. To check this, simply take a clod of soil, dug out with a spade, in your hands and try to crumble it. It's a simple test that requires no tools.
2 - A smell of undergrowth
When you collect soil, if a pleasant, earthy scent reaches your nostrils, that's a good sign. These aromas are produced by the presence of humus, moss, microorganisms, and decomposing branches, leaves, or twigs. You often smell it in the woods at the base of trees. It's a sign of rich, fertile soil.
3 - Biological life (worms, mycorrhizae)
The presence of burrows in the soil is a sign of earthworm activity. Casts, which are the excrement of anecic earthworms or marine worms, can also be observed. These structures play a major role as they promote plant growth and aerate the soil. They contain nitrogen, phosphorus, potassium, magnesium, and calcium.
Mycorrhizae are an symbiotic relationship between fungi and plant roots. This symbiosis promotes plant growth. Some plants have a greater potential for mycorrhization than others. This is the case, for example, with grasses such as corn, peas and beans, or leeks and onions.
4 - Good water retention without engorgement
Soil that retains water effectively provides sufficient hydration for plants. However, efficient drainage is essential to prevent waterlogging and stagnation. Not all soils react the same way to water input:
- Clay soil quickly becomes waterlogged in the face of repeated heavy rains: water does not circulate very well.
- A crust can form on silty soil when exposed to rain and watering.
- Humus-rich soil retains water well, like a sponge.
- Sandy soil is less prone to waterlogging thanks to its porous texture which promotes drainage.
5 - A dark color
Dark-colored soil indicates efficient drainage of water, nutrients, and air. Black soil is composed of a high density of organic matter: humus, often covered with a layer of decomposing leaves, especially in autumn. Yellow soil is a sign of a high iron oxide content. The presence of rust spots indicates stagnant water and/or heavy metals.
6 - A balanced pH
A balanced pH is ideal for healthy soil and plant growth. It should be between 6 and 7. There are several methods for determining it: pH paper, which changes color depending on the soil type, or a more precise pH meter that uses an electrode. Laboratory analysis is the most reliable process. Keep in mind that pH varies with the seasons. For example, in winter the pH is higher because biological activity slows down and acidification is low.
Analyzing your garden soil: a concrete example
Why should gardeners analyze their soil?
If you garden or have a vegetable patch, analyzing your soil is essential. Firstly, to determine whether cultivating your garden and consuming its produce poses a risk. Indeed, some pollutants, such as PFAS, are persistent and contaminate plants and water.
Another benefit? Knowing your soil type and whether fertilizers, amendments, or other corrective measures, such as adding lime to overly acidic soil, are necessary. Understanding your soil type—clay, silt, sand, or humus-rich—will guide you in choosing the most suitable plants. For example, if you have sandy soil, root vegetables (carrots, beets, potatoes, etc.), lettuce, strawberries, or parsley thrive.
Simple methods for individuals
The simplest method is to test the soil pH using test strips or a pH meter. Particle size analysis is also quite easy to perform using a soil sample and a jar filled with water. You can also simply observe the soil sample: its smell, color, the presence of earthworms, humus, roots, etc. There are also specific kits available, such as the one from Pouryère, for laboratory analysis of the soil's agronomic quality.
When and how often should an analysis be done?
A soil analysis is relevant when you move onto a new property or start a vegetable garden. It can also be useful after applying fertilizer to check the effectiveness of the amendment. After that, under normal conditions, an analysis every 5 years is sufficient, except in cases of proven pollution or accidents such as severe flooding or landslides.
What to do after the analysis?
Read the results of a test or laboratory
If you use a laboratory, the technician will interpret the analysis results for you. You'll receive both the normal values and the values specific to your soil for easy interpretation. Some service providers, like Pouryère, also include soil improvement advice with their analyses. This will help you determine what amendments and adjustments to make for a healthier vegetable garden or flower garden.
Adapting practices: soil amendments, fertilizers, soil rest…
Once the soil analysis results are available, some adjustments may be necessary. If the organic matter content is too low, fertilizer will likely be required. There are natural methods to strengthen plants, such as compost, seaweed, wood ash, or green manures like alfalfa, rye (which provides nitrogen), or white mustard (rich in phosphorus).
Soil that is too acidic requires the addition of lime, a process known as liming. Some soils simply need to rest without sowing for several months or years to regenerate.
Repeating the analysis after a few months: the follow-up
After making changes to your soil, follow-up is helpful. Conduct another analysis a few months after the amendments or the resting period. This will allow you to determine if the adjustments have been effective or if you need to intensify your efforts.
The author of the article: Joseph OLIVIER
Joseph Olivier is an entrepreneur in the environmental sector. Originally from Nantes, he trained in waste management before creating a circular economy consulting firm . In 2022, he co-founded Pouryère with the ambition of addressing citizens' concerns about soil quality in France and access to environmental data.
Frequently Asked Questions (FAQ)
Can I analyze my soil myself?
Yes, you can analyze your soil yourself. There are pH testing kits and simple chemical tests to assess nutrient content. To determine the nature of your soil (clay, silt, sand, etc.), perform a sedimentation test by placing a small amount of soil in a jar filled with water.
At what time of year should I have an analysis done?
Choose a time when the ground is neither frozen, nor hardened by drought, nor waterlogged. Autumn is the best time, as the soil is still warm, and you'll have time to add fertilizers and soil amendments before the first spring sowings.
Is this useful for a small vegetable garden?
Yes, analyzing your soil is also useful for a small vegetable garden. If only to ensure that the vegetables you'll be eating are healthy thanks to unpolluted soil. And to know which types of plants are best suited to your soil type.
How much does a lab analysis cost?
Expect to pay a few hundred euros for a complete agronomic analysis in a laboratory, or more likely between 700 and 1,000 euros if you entrust the sampling to a technician who will come to your site. Sampling kits with laboratory analysis are available at a much lower cost. For around 200 euros, you can collect the samples yourself but still benefit from in-depth analysis and interpretation of the results in a laboratory.
Why trust Pouryère for your soil analysis?
Comprehensive support, from sampling to interpretation
Pouryère supports you throughout the entire soil analysis process. Our sampling kits come with a comprehensive guide to walk you through the process. Once you've completed the analysis, simply send us your samples for full analysis and interpretation, which takes approximately ten days.
Solutions for individuals, farmers, communities and businesses
Each soil analysis kit is specialized and pursues a specific purpose:
