The ground has two essential functions:
- serve as a support,
- feed the plants.
The type of soil in your garden is ultimately much less important in itself than how you know how to use it. It is important to emphasize that most cultivated plants adapt to a wide diversity of soils. As for soils poor in nutrients, it is easy to improve them.
However, all gardeners know that there are soils that are particularly pleasant to work with and provide plants with the maximum for rapid and harmonious development. These are generally soils with good fertility, allowing air and water to penetrate well, rich in organic matter in the surface layer and whose pH, which is rather acidic, is towards neutrality. The main elements must be taken into account, which are the texture of the soil, its structure and its composition.
Some elements of appreciation
Soil texture
It depends on the size of the different elements that make up the soil: sand, silt, clay, etc. Thus, good garden soil will be a mixture of 20% clay in small particles, 40% silt in medium particles and 40% sand in larger particles. This type of texture corresponds to a soil that retains water well while being aerated and easy to work because it does not stick to tools.
The structure
This is the way in which the constituents of the soil are associated. A sandy soil is thus characterized by its lightness, a clay soil by its compactness. Good garden soil will fall between these two extremes, with a loose structure.
Soil drainage
Properly drained soil can quickly absorb rain and become wet again. Drainage must be done on the surface, but also in depth.
A simple test consists of digging holes (with a crowbar for example) 80 to 90 cm deep, filling with water and as soon as absorption is complete, filling again. From this point on, the water level should drop by 2 to 3 cm per hour and disappear within 24 hours. If the phenomenon takes longer, the permeability of the soil is poor. It is necessary to drain.
Chemical composition
Only a laboratory analysis (or more briefly using an amateur kit) will make it possible to determine the distribution of mineral elements and decide on possible additions and corrections.
Organic matter
Decomposed by the action of fungi and bacteria, it will produce humus, the presence of which is essential to retain nutrients. Additionally, organic matter increases the ability of sandy soils to hold water and improves the texture of clay soils.
The color of the ground
It does not act very significantly, although dark floors retain heat better than light floors. This is a useful criterion for determining the type of soil you have.
Acidity or alkalinity
It is appreciated with the pH whose neutrality is marked by the number 7. The majority of plants prefer neutral soil.
| Recognition characters | Almost black soil, rich in plant debris. Retains moisture well without sticking. Slightly spongy and easy to work with. | Dark brown soil. Granular. A handful held tightly in the hand stays in shape, but then crumbles easily. Harmonious mixture of clay, sand and humus. The higher the proportion of humus, the richer, warmer and easier the soil is to work. | Gray, compact and sticky soil. Squeezed in the hand, it is difficult to crumble afterwards. Formation of clumps that are difficult to break up and become hard when drying. | Gray colored floor. Squeezed in the hand, immediately crumbles without staying in shape. Does not retain water and does not form clumps. | Whitish soil without much cohesion. |
| Nature | Humous soil. | So-called “garden” land or loam. | Heavy earth. Clay soil. | Light earth. Sandy soil. | Limestone soil. |
| Qualities | Its lightness makes it easy to work with. Excellent support for all “heather earth” plants; Acidic pH. | Water and air permeability. Easy work. Soil retains fertilizing elements well and retains humidity. Perfect for virtually all ornamental, fruit or vegetable crops. | Very fertile, because it retains mineral particles from fertilizers well. | Easy to work, even after heavy rain. Excellent drainage and good permeability to water and air. Soil warms up quickly. | Only for calcicole plants. Difficult for the garden. |
| Defaults | Its acidity which is not suitable for many plants, and which must be corrected with limestone amendments. | None. | Hard work. Hardens into cracks in dry weather. Sticky and heavy if humidity is high. Not very permeable to water and air, which results in a cold floor. Need for frequent drainage. | Dries very quickly, hence the need for regular and abundant watering. Does not hold fertilizer well. | Causes chlorosis (yellowing) of leaves on many plants. Poor retention of fertilizing elements, resulting in frequent deficiencies. |
| Improvements | Liming to reduce acidity. Drain if necessary. | Regular fertilizer applications to maintain fertility. | Liming to improve the structure. Drainage most often essential. Addition of sand to lighten it and especially spreading of organic matter (compost, peat). | Regular contributions of organic matter (compost, peat), and fertilizers which will maintain good fertility. | Copious and regular contributions of acidic humic amendments and fertilizers. It generally takes several years to consider growing plants sensitive to limescale. Watering with iron chelates in case of chlorosis. |