Last updated on October 23rd, 2023 at 08:24 pm
It is an advantage for gardeners to know about the garden soil, because not every plant grows in every soil! The soil requirements of the various vegetables and herbs are often very different. Therefore, the condition of the garden soil may well be the reason why a plant does not feel comfortable and does not thrive properly. Soil identification helps with targeted improvement and successful planting.
Contents
Classification into three soil types
So it makes sense to know the soil conditions of your garden. Only when you know how it is composed can you work it properly according to the needs of the plants, care for it and fertilise it properly. It is relatively easy to determine the composition of the soil yourself. With the so-called feel test, the soil can be divided into three types: You can determine whether it is a sandy soil (light soil), a clay soil (medium soil) or a clay soil (heavy soil). You analyse the soil by determining the proportion of sand, silt and clay. These terms define the grain size of the mineral soil components. Light soil has a high sand content (large grain size), medium soil has a high silt content (medium grain size) and heavy soil has a high clay content (fine grain size). Use the table below for diagnosis.
Simple soil identification with the feeler sample
For the diagnosis it is absolutely important that the soil is slightly moist. To determine the soil, first take some garden soil between your thumb and index finger. The sample is now triturated to determine the granularity by tactile sensation. Does the soil feel grainy-rough or smeary-smooth?
Now form a ball in your hand to see how cohesive and sticky the sample is: Does it break apart right away or does it hold together very well? Is the palm of the hand sticky-dirty or does only little soil adhere to the hand lines?
Next, the mouldability is tested by rolling it out. The soil sample is rolled into a sausage between the palms of the hands. When doing this, pay attention not only to the kneadability, but also to the appearance of the roll.
A soil with a high sand content cannot be rolled; it disintegrates in the hand and feels rough and sandy. If the roller breaks into crumbs at the thickness of an index finger or becomes very cracked, then the soil has a high silt content (clay soil). If the soil is very easy to knead by hand and can be shaped without breaking apart, it is a soil with a high clay content. It can be rolled out to almost pencil thickness. This type of soil is called “heavy soil”. The shinier the grating surface, the higher the clay content.
The result of the feel test can usually be confirmed by indicator plants that often appear as weeds in the garden. For example, creeping buttercup or goose cinquefoil are often found in heavy soils.
Determination of soil types
| Diagnosis | Light soil (sand) | Medium soil (loam/silt) | Heavy soil (Clay) |
| Grinding between the fingers (graininess) | Individual grains clearly visible and palpable, rough and grainy, (graininess large) | hardly any individual grains visible and palpable, floury, much fine substance (graininess medium), | not granular, very much fine substance, greasy and smooth (granularity small) |
| Shapes in the hand (binding and stickiness) | Hardly cohesive, not mouldable, not sticky Dirt adheres only in the hand lines | Cohesive, moderately malleable, adheres and sticks, hand little soiled | Very cohesive, very malleable, distinctly sticky and greasy, very strong soiling of the hand |
| Rolling out between the palms (malleability) | Rolling into a sausage not possible – it crumbles | malleable and rollable – but cracked, thin rolls break, matt appearance and rough rubbing surface | very good formability, rolls in pencil thickness and thinner possible, shiny rubbing surface |
After soil identification: What does light, medium and heavy mean for the soil?
Light, sandy soils can hardly store water and have a low nutrient content. They therefore dry out very quickly in summer. However, they warm up quickly in spring, are well aerated, have good root penetration and are easy to work – hence the name light soil. Seeds can be sown early in the spring. Many Mediterranean herbs that do not tolerate waterlogging and prefer nutrient-poor sites feel at home in these soils. These include rosemary, lavender, sage and thyme. Plants that favour more nutrient-rich and moist sites do not find the best conditions here. Tomatoes and cauliflower, for example, do better in clay soils.
Heavy, clayey soils become hard and burst open in dry conditions. When it rains, they have poor water retention, the clay sticks together and soggy puddles form. The soil sticks to boots and spades. Such soils tend to compact, making root penetration very difficult. They are poorly aerated and warm up very slowly in spring. Seeds can therefore be sown later than in light and medium soils. They are impermeable, tend to accumulate moisture and are difficult to work – hence the name heavy soil. However, such soils can store nutrients and water for a long time. Heavy soils are hardly suitable for Mediterranean plants. All vegetables that avoid waterlogging do not feel well here and tend to rot. Root vegetables also develop poorly here, as they have a hard time penetrating the soil.
The medium, loamy soil is the ideal garden soil for most vegetables and herbs. It is crumbly and easy to work. At the same time, it contains enough nutrients and can store sufficient water.
Special features of the critical soil types
| Soil type | Special features | Measures |
| Heavy soils | Disadvantages: slow warming compaction during drought cracked and hard poor water drainage, waterlogging poor aeration difficult to work Advantages: High nutrient content Good water retention | Loosen soil drainage by digging up deep-rooted green manure Mix in sand and lava granules Mulching |
| Light soils | Disadvantages: low water holding capacity little nutrients Advantages: quick heating good aeration easy cultivation good water drainage | Supply of organic fertiliser Green manuring Mixing in bentonite (clay meal) Mulching |
Problem soils can be treated: Mix and improve soil types
Overall, it makes sense to increase the humus content of light soils. This is done by regularly adding organic materials (compost, mulch, manure, green manure). Clay flour (bentonite) and rock flour improve the cohesiveness of the sandy soil and increase its water storage capacity.
Heavy soils must be dug up spade-deep in late autumn so that the frost can reach deep into the soil and loosen it up (frost-rottenness). This soil must also be loosened regularly in summer. In spring, various improvers are added to the heavy soil and worked in: Fine sand, lava granules and stone dust provide better aeration of the upper layers. Compost, mulch and bark humus improve the soil by supporting soil life.
Deep-rooting green manures such as oil radish or white lupine loosen the subsoil. With these measures, the heavy soil will develop positively over the years. Until then, however, you do not have to give up growing Mediterranean herbs and delicate vegetables: Create raised beds, a herb wall or a herb spiral, which you then fill with a 2:1 mixture of your heavy garden soil and sand.