5 things to know about your soil for better yields

The soil on which you grow has a fundamental impact on production. It is an aspect to consider as soon as you start a greenhouse production project.

But it is not easy to differentiate the types of soils between them. Each one has its own peculiarities that you have to identify in order to recognize them. You also need to know more than just the type of soil, you need to know its characteristics. Is my soil poor in nutrients? Too acidic? Too calcareous? Optimize your production by getting to know your soil with these 5 essential things to know!

1. What type of soil do I grow in?

Sandy soil

A sandy soil is composed of more than 60% sand. It is light in colour. Its texture is granular to the touch. Light and airy, it is very easy to work. It is one of the main types of soil found in Quebec. It is well suited for growing asparagus, carrots, potatoes, beets, radishes, turnips, celery, strawberries or any other plant with a taproot.

Clay soil

This type of reddish brown soil contains more than 1/3 of clay. Its heavy and compact aspect makes it difficult to work in all seasons. It is characterized by its sticky texture when it is wet and hard when it is dry. It is one of the main types of soil found in Quebec. It is a great soil for growing tomatoes, cabbage, cauliflower, broccoli, brussels sprouts, eggplant, etc. Avoid root vegetables that do not like asphyxiating soils, desert plants and others that need quick drainage.

IMPORTANT: To aerate a clay soil and improve its drainage, add a copious amount of compost every year. But no sand, to avoid destructuring and impoverishing the soil.

Loamy soil

This type of soil is usually found near waterways. Loamy soil is powdery to the touch when dry. This soil tends to form a crust on the surface due to rainfall and watering. This makes it impermeable to water and air. In this soil, avoid growing root vegetables (including parsnips and carrots), desert plants and others that need quick drainage. Instead, aim for wheat, corn, melon, beets, raspberries, strawberries, etc.

IMPORTANT: Spread compost or manure to prevent the soil from being left bare. This will also help keep the soil fertile.

Loamy soil

A loamy soil is made up of about 40-60% sand, 30-50% silt and 15-25% clay. The properties of this soil are maintained and improved by regularly adding organic matter. This type of soil is excellent for most fruits and vegetables. But it is particularly suitable for growing wheat, cotton, sugar cane, berries, legumes, etc.

2. What is the structure of my soil?

The structure of soil refers to the way the particles of sand, silt and clay are arranged in relation to each other. In good soil with an ideal structure, the sand and silt particles are bound together in small clumps, called aggregates.

The more empty spaces there are between the aggregates, the better water and air can circulate. It is also easier for roots to sink into the soil. These large voids are called "macropores". There are also small voids, called micropores, which hold the water that plants need.

Clay, sand and loam soils rarely have an ideal structure. However, they can be improved by incorporating soil amendments. For clay soil, you can improve its structure by adding organic matter in the form of compost or composted manure. These amendments are best incorporated in late fall.

It is preferable for sandy soils to incorporate these amendments in early spring, because working this type of soil in the fall promotes erosion.

Finally, for a loamy soil, improve drainage and aeration with large additions of compost or composted manure. As with clay soils, it is best to incorporate these amendments in late fall.

3. What is soil pH, and how do I calculate it?

The pH, or "hydrogen potential" is the unit of measurement for the degree of acidity of the soil. The amount of pH in the soil affects the availability of nutrients. Soil that is too acidic or calcareous prevents plants from properly absorbing the minerals they need, even if they are in the soil. A pH that is not appropriate for your crops unbalances the soil structure, promotes fungal diseases and threatens the survival of many beneficial living organisms.

It is counted on a scale of 1 to 14. Your soil will be calcareous if its pH is above 7. When it is below 7, it will be acidic. If it is close to 7, it will be qualified as neutral. Most soils have a pH between 4 and 9. The ideal is soil with a slightly acidic picohenry, around 6.5. This is suitable for most plants.

The simplest technique is to place a handful of soil taken from a depth of 20-30 cm in two containers. Pour a few drops of white vinegar on one of the handfuls of soil. If a white foam forms, your soil has a calcareous tendency.

In the other container, mix the soil sample with a little rain or demineralized water. On the wet soil, sprinkle some bicarbonate on top. If an effervescent reaction (gas production) occurs, your soil is acidic. If neither reaction occurs, your soil is neutral.

You could also buy a pH test kit. It works by using a reactive chemical solution, mixed in a tube with a soil sample and distilled water. You then dip a strip of pH paper into it. The paper will turn a certain colour. You will have to compare the colour obtained with the colour chart to determine the pH value of the soil.

4. What if my soil is too acidic?

The perfect acidity for soil is around 6.5 pH. A soil that is too acidic has low microbial activity. There are also a few earthworms. Too much acidity will disturb the assimilation of nutrients necessary for the growth of plants.

To compensate for this acidity, use fertilizers rich in calcium, preferably organic. Lime or wood ash are also good alternatives to amend the soil. In addition, in late fall, add limestone in small doses in the form of lime, chalk or dolomite.

5. What to do with soil that is too calcareous?

You will recognize chalky soil by its light and stony appearance. It will look a bit whitish and chalky. This soil is permeable to water. It will warm up quickly in spring but will tend to dry out quickly in summer. This will form cracks in the surface. Rain makes it easily muddy and sticky.

You don't want soil that is too high in limestone, because limestone causes deficiencies in plants. Like chlorosis, it can block the assimilation of certain minerals.

To acidify your soil while continuing to enrich it, incorporate a large quantity of organic matter each fall. You can use sulphur, iron sulphate, conifer needles or composted wood chips as amendments.

No one type of soil is better for your vegetable production than another. Each has advantages and disadvantages. In fact, the quality of a soil depends on the use you want to make of it. It also depends on their geographical location, and therefore on the climate. In the end, the best soil you could wish for is a well-balanced soil: it should contain a good proportion of clay, silt and sand, as well as a good quantity of organic matter.

For agronomic advice on greenhouse production, don't hesitate to contact us!