Soil types 

Index:

• What soil type do you have in your garden
• Types of soil
• Determining the acidity (pH) of the soil
• What is mulching
• Humus
• Groundwater

What soil type do you have in your garden 

In virtually all gardens the soil consists of particles of minerals and organic material plus water and air. Those particles of minerals can be of various sizes: the coarsest are grains of sand, and if they become finer, it is called silt which is deposited as clay. There are innumerable different compositions which each have a different name.

Here’s a way of establish the soil type by hand and by eye:

1. Take some soil in your hand and try to knead it into a ball.
2. If it does not fall apart, it contains a substantial proportion of clay particles.
3. If it does fall apart, then the percentage of sand particles is greater.
4. If you are totally unable to knead it into a ball and the (dry) soil trickles through your fingers, then you have poor sandy soil.
5. If the soil feels fibrous and is dark in colour, it is peat soil or at least has a high proportion of organic material. Generally speaking, the darker the soil the more organic material it contains.
6. Also rub some soil between your fingertips. If it clearly feels grainy, and you can see small stones, then it is sandy soil. If it feels smooth, you are dealing with a clay soil. 
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Gardening books identify the following types: 

- Sandy soil

Consists mainly of grainy particles which can be round and worn down or have rough edges (sharp sand). There is always a lot of air between the particles. Sand is a light soil and easy to work. The disadvantage is that water drains through it quickly. Pure sandy soil therefore dries out fairly quickly and fertiliser and other nutrients are rinsed out into the groundwater.

In the spring and autumn you should work in substantial quantities of organic material and apply a layer of mulch. Do not dig it over too vigorously. It is often enough to dig over a sandy soil thoroughly once when creating the garden and then ensuring that the percentage of organic material is maintained.

Determine the pH and if the soil is fairly acid, you can add lime. Do that well before you apply any fertiliser, since the nitrogen in the fertiliser and the lime will react with one another.

- Loamy soil

This has the perfect balance of characteristics. Any gardener would like to have this soil – a mixture of sand and clay particles. It is very fertile and good to work, retains enough water, and excess water can drain well. Improve it by applying a substantial mulch layer every spring once the soil has warmed up.

- Clay soil

Clay soil is very fertile, but hard to work. Mainly because there is so little air in between the fine soil particles. Clay soil retains a lot of water, but in the summer it can sometimes become as hard as concrete. It shrinks and cracks when it dries out, whilst it becomes one wet, stick mass in winter.

Dig over heavy clay soil in the autumn and work through organic material. Leave the raw clods lying there - they need to be frozen apart. Walk on clay soil as little as possible in the winter. Scattering chalk also improves the structure, as does applying a mulch layer in the spring when the soil has warmed up.

- Chalky soil

Chalky soil can be identified by the lumps of white or pale yellow lime which are present in the usually light-coloured soil like little stones. Chalky soil is fertile, but dries out quickly. Not all crops do well in it. Most chalky soils developed below ancient seas from the skeletons of animals and algae.

Limestone is usually full of fossilised remains and consists of all sorts of calcium compounds. You can check whether the soil in your garden is very alkaline or acidic using a chemical test. Work organic materials into the soil every spring and cover it with a thick layer of mulch. Scattering gypsum helps to loosen the soil.

- Peaty soil

Peaty soil consists mainly of dead plant remains, i.e. organic material. Peat is always acidic. It is also dark. The fibrous structure and the enormous ability to hold water means that peaty soil can remain wet for a very long time. But if it dries out – which can happen in long, hot summers – it is very difficult to get it moist again. A dry sod, practically a lump of dried peat, is also almost impossible to get wet.

Peaty soil already contains a lot of organic material. The problem usually lies in the drainage. You can boost drainage by digging grit, sand or other gravel-like material into the soil. Increasing the amount of mineral materials also improves the nutritional value.
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Determining the acidity (pH) of the soil 

There are two extremes: pH 1 is extremely acid and pH 14 is extremely alkaline. The switchover point is at pH 7, where the soil is equally acidic and alkaline. Most garden plants and fruit trees prefer a slightly acid soil, with a pH of around 6.5. There are also acid-loving plants, such as many types of heather, rhododendrons, Pieris and blueberries. The biggest variety of plants occurs on chalky soil. You can buy testing kits for measuring the pH in garden centres.
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What is mulching 

Mulching is covering the soil with a layer of permeable material. That can be mineral, such as gravel or chippings, but also organic: bark chippings, old cow manure or cocoa shells. Organic material is gradually absorbed into the soil by the soil-life and converted into humus.

A layer of mulch prevents the soil from drying out or compacting quickly. Spread a layer of at least five centimetres on all open soil and around plants. This also prevents a lot of weed growth.
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Humus 

Humus is the top, living layer of the soil with mineral particles and organic material. In the humus layer the soil-life (bacteria, fungi, worms, enzymes) arranges a gigantic recycling process whereby dead or organic material is broken down into substances which plants can absorb as nutrients.

Humus retains water and allows excessive water to drain away. Soil with a lot of clay becomes more workable and looser through the formation of humus, whilst sandy soils gain a more coherent structure. The mixing creates a homogenous structure.

Plants which are growing in a layer of humus are effectively growing in a sort of astronaut food for plants. It contains everything they need. The only thing you need to do is ensure that the humus layer is maintained by regularly adding organic material. Nature does the rest.
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Groundwater 

Rainwater sinks into the soil and continues to sink until it hits an impermeable layer (or rock). A continuously wet zone is created above such a layer which can be metres thick and through which the water moves gradually. That is the groundwater.

If there is a lot of water, the top of that water zone will be higher than if it has been dry for a long time or a lot of water has been pumped away. There can be various groundwater layers present in the soil above one another, separated by impermeable layers. Hence there are enormous underground lakes underneath the Sahara.

If you dig a hole in your garden, water will flow into that hole at some point. That means that you have reached the groundwater layer. 
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