Simple soil test: Determine soil type & quality

20.05.2019 / Reading time: 4 minutes

When choosing the right vegetable plants, the type of soil you have in your garden is crucial. The soil type also influences how often you need to water and fertilize in summer. To determine the soil type of your garden, there are two key parameters: the particle size and the humus content.

This Article Contains:

Testing soil quality: the sludge sample
1) Determine soil type with the sludge sample
2) Determine humus content using the sludge sample

Testing soil quality: the sludge sample

With the finger test, you can easily determine your soil type without any tools. On the one hand, you can determine the particle size and therefore the composition of your soil. On the other hand, you can use the color to find out the humus content of your soil.

1) Determine soil type with the sludge sample

The type of soil is defined by the particle size, the so-called grain size. The particle size is a good indicator of whether your soil is heavy or light. The larger the particles, the lighter. If you have a lot of fine clay particles in your soil, it is a heavier soil. It holds water longer, a great advantage in dry summers. In addition, heavy soils are often richer in nutrients than sandy soils. You can find more information about heavy and light soils here.

Understanding soil composition: Granulation and grain sizes

Grain size	Particle size
Stones and gravel	> 2 mm/ 0,07 in
Sand	0,05 - 2 mm/ 0,002 - 0,07 in
Silt	0,002 - 0,05 mm/ 0,00007 - 0,002 in
Clay	< 0,002 mm/ 0,00007 in

Materials for the slurry sample

What you need

Materials for the slurry sample

- Large beakers or screw-top jars for the samples
- Your soil sample
- water
- Spoon or spade

Instructions: How it works

To find out the particle size, fill a handful of soil from your bed into a jam jar. Fill the rest of the jar with water, close it and shake vigorously until all the clumps of soil have dissolved. Then leave it to stand for one to two days. You should now see two layers at the bottom of the jar. A coarse-grained, sandy layer at the bottom and a finer layer of clay particles on top. If the finer layer is significantly thicker than the sandy layer, the soil is rather heavy. In optimal garden soil, both layers are approximately the same thickness. If the sandy layer is thicker, the soil can be classified as light.

Sludge sample to determine soil type — On the far right is the result of the test: the coarse and fine layers are roughly the same thickness. An indication of a good soil composition. Photo by Gabriel Jimenez on Unsplash

2) Determine humus content using the sludge sample

The color of the soil provides information about the humus content of the soil. The blacker the soil is when moist, the higher the humus content. A high humus content means that the soil is rich in nutrients, has a healthy soil life and can also absorb and retain a lot of water. Dark, humus-rich soil is particularly suitable for growing plants with high nutrient requirements. These so-called heavy eaters include, for example, various cabbage plants or tomatoes. If your soil is light brown in color, you should increase the proportion of organic matter in the soil. You can do this by mixing in mature compost, for example. You can find detailed information on soil improvement here.

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Author

Jonas

Jonas studied agricultural biology. He discovered his passion for plants and gardening through an internship at a permaculture NGO. Since then, he has been gardening on his balcony and in community gardens.

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