Soil analysis: an eco-responsible practice

You are ready to make a flower bed or a vegetable garden? You want to improve the look of your lawn? You intend to plant trees and shrubs? First, you must know the composition of your soil and its reserve in nutrients to sustain the plants you want to grow.

Depending on where you live and the history of your land, soil composition may vary greatly. Furthermore, over the years, the soil can be impoverished. Plants draw nutrients from the soil; some elements are washed by rain, while others are naturally less absorbed by plants. Depending on the type of soil, water and nutrients are more or less retained by the soil.

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Soil Analysis
Frequency
What’s included in a soil analysis?
What you learn
When to take a soil sample?
Procedure to follow

Soil Analysis

Soil can be transformed or improved and for that you must know what it consists of. Chemical analysis of the soil measures the content of susceptible nutrients to be absorbed by plants. It informs you on the quantity of nutrients, the content of organic matters, fertility and the level of acidity (pH). Knowing the precise composition of the soil allows you to provide better growth conditions to plants.

Frequency

It is not necessary to make an analysis every year for the same location or a homogeneous zone. Gardeners often choose one section a year (ex: lawn), an other the next year (ex: vegetable garden) and so on, to spread costs and improvement treatments of the soil over several years.

What’s included in a soil analysis?

Generally, when you bring a soil sample to your RONA retailer, the following elements will be analysed: type of soil (particule size analysis), acidity (Soil pH, Buffer pH), and contents of calcium, phosphorus (P), potassium (K) and micronutrients.
    Particule size analysis consists of a visual evaluation of soil dominance. Compact, lumpy soil that is difficult to break up is considered clayish. Soil that does not compact and disintegrates easily is considered sandy. Brown and black lumpy, spongy soil is considered organic.

    Soil pH refers to the soil's acidity or alkalinity. It is determined with the help of a pH meter and an electrode which measure the hydrogen ions in the soil on a scale ranging from 4 (very acidic) to 8 (very alkaline), 7 being neutral. Generally, plants require a slightly acidic or neutral pH, between 6,0 and 6,5.

    A buffer pH test will be realized on soil « water pH » below 7,0. The result of a buffer pH solution will determine the amount of lime required to correct soil acidity from the original soil pH to the ending soil «water» pH.

    P is the symbol for phosphorus. The analysis measures the phosphorus acid contained in the soil. Phosphorus is an essential nutrient and promotes plant growth and the development of a good root system. It plays an important role in production and fruit bearing.

    K is the symbol for potassium. The analysis measures the potassium contained in the soil. Potassium increases the plant's resistance to insects, diseases and stress such as drought. It plays an important role in flowering and improves the taste and colour of the fruit.

    Micronutrients. Consists of elements such as calcium, magnesium and iron. The analysis provides the quantity of these elements in the soil. Calcium favours the growth of young roots and fruit bearing. Magnesium plays an important role in the green colouration of the foliage, contributes to the ripening of the fruit and promotes the absorption of phosphorus and nitrogen by the plant. Iron is an essential element for plant growth and green colouration of leaves.

What you learn

  • The qualities and deficiencies of the soil so that you can provide the appropriate fertilizers and amendments;
  • Choose plants adapted to your soil;
  • Contents of nutrients of your soil (P, K, micronutrients);
  • To choose plants adapted to the condition of your soil.

So, if you don't know your soil well or, alternatively, if you don't rectify soil problems when necessary - and this may well entail one analysis a year - you risk wasting time and money.

When to take a soil sample?

It is important to always take a sample at the same location, at the same time of the year and before fertilizing or amending your soil to avoid distorting the results of the analysis

In general, gardeners take samples in the spring or fall as long as the soil is not frozen or saturated with water. Prioritize fall because you could add lime during that period if required, as the application of fertilizer can not be done at the same time as liming. So, the time to do take a soil sample will depend on the work or planting you intend to do.

Procedure to follow

Before proceeding, you must know that the representativeness of the test results will depend on the quality of sampling that you take. Each sample sent to the laboratory must represent truly the nature and composition of your soil. Therefore, here are some tips for a successful sampling.

Attention: Avoid sampling immediately after amending or fertilizing.

Precautions
  • Take one sample for each section of your yard. For example : one for the lawn, one for the vegetable garden, one for the flower bed (3 sections = 3 analysis = 3 bags);
  • Wash the tool that will be used to take the sample. This tool can be a shovel, a trowel, a bulb planter, etc.;
  • Do not touch the sample with your hands;
  • In the wanted location, do randomly 10 to 15 samples by taking a few spoonfuls of soil in each spots. Samples must be put in a very clean container;
  • Avoid sampling from borders, roads, under rocks, etc.;
  • Sample of soil should be taken at 15 cm deep for the lawn, 20 cm for the vegetable garden and 30 cm for trees without taking any from the upper section. Basically, sampling is done at root level;
  • Sift through the soil and remove rocks, weeds and other debris mixed in the soil. Always use gloves when manipulating the samples.

How to proceed
  • Take all your samples at the same depth to provide the accuracy of the evaluation;
  • When your 10 to 15 samples are in the container, break the clumps and mix the soil in the container;
  • From the container, take 500 grams or about one cup of soil and transfer in a clean plastic bag (ex: Ziploc®). Some garden centers or laboratories provide a small sampling box for the soil;
  • Identify your sample(s) if there is more than one analysis to be made;
  • Bring or send your sample(s) at your RONA retailer. An adviser can help you complete the application form that must accompany the samples to the laboratory.


The laboratory will analyze your samples for a fee. An adviser in-store will help you interpret the test results and draw the most relevant recommendations. With the results, you have all the details about the state of your soil fertility. You will then be able to know which products to use, the dose to apply, the frequency, etc. So, spending a few dollars for soil analysis is a good investment!
So, if you don't know your soil well or, alternatively, if you don't rectify soil problems when necessary - and this may well entail one analysis a year - you risk wasting time and money.
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