The soil combines air, water, rock and organic matter. But not only that, it is alive! Countless microorganisms and small animals live in it, which are indispensable for the soil. Every dead plant is reabsorbed into the material cycle by the soil organisms. The dead tissue is broken down into its components and transformed so that new life can emerge.
Soils have different compositions depending on their location. Each soil type, with its individual characteristics, has advantages and disadvantages. In this article, you will learn about the properties of heavy and light soils and how you can make your soil more fertile naturally. Soil life is very important here, it just needs a little support sometimes to meet your needs.
At a glance
Heavy soils = loam & clay soils
Problem: Soil compaction
Solution: Soil loosening
How it works:
Mix in coarse particles (e.g. humus or sand).
Sow green manure
Light soils = sandy soils
Problem: Poor storage of water and nutrients
Solution: Improve storage capacity
- Incorporate organic material into the soil
- Sow green manure
- Mix in clay or clay powder
- Permanent mulch layer
- Use fertilizer that is difficult to dissolve
- Use our simple soil test to find out what your soil’s rough composition is.
As the name suggests, heavy soils are relatively difficult to work with. Everyone who has a clayey soil in the garden knows the problem: If it is too dry, cracks form and the soil becomes hard as a rock. The other extreme also makes every gardener despair: If the soil is too wet, it also resists any tillage. Heavy soils can therefore only be worked in a certain condition; they must be neither too dry nor too wet. In agriculture, they are therefore often referred to as minute soils, because the tillage period is very short.
Clay soils contain a number of fine pores (= smallest cavities), which are filled with air or water. The fine pores ensure that water and nutrients are well retained. Heavy soils therefore have a high storage capacity. As a gardener, you benefit from this property because you need to water and fertilize less often.
However, because of the high water content, the soil warms up slowly in the spring, so it may take longer for your seeds to germinate. The narrow pores can also cause waterlogging and lack of air in the soil. Both of these are a death sentence for the growth of your plants, and as a gardener, are to be avoided at all costs!
Improve clay & loam soils
The most important thing to do when improving a heavy soil is to loosen up the soil structure. Looser soil structure allows water to percolate faster and roots to breathe easier. It also greatly improves rootability, making it much easier for roots to penetrate hollow passages. These hollow spaces are crucial for success with root vegetables, for example!
Simple soil loosening
- The easiest way to create small voids is to mix in coarser particles. For example, you can use mature compost or sand. The coarser particles allow air to penetrate more easily, improving soil aeration and allowing water to percolate. If you don’t have your own compost, you can also use fresh garden soil. We have used ASB Greenworld’s garden and raised bed soil for this purpose in the past and were very pleased with the results.
- Once you have loosened your soil, you should also mulch it. The mulch serves as a protection against environmental influences. It maintains the crumbly soil structure and protects against blazing sun and heavy rain. It also provides food for earthworms, which are attracted to the plant debris. Ecosystem engineers mix the soil and further loosen it.
- The plant kingdom can also help you loosen the soil. Green manuring does not only help with nutrient enrichment. The plants loosen the compacted soil with their roots, saving you at least some of the tedious work. In permaculture, comfrey is also often used to loosen the soil. The strong roots remain in the soil, where they are decomposed by soil organisms after the plant dies. Over time, hollow tunnels form, which provide good aeration. The large leaves are also excellent for mulching or making slurry.
- In the literature and on the Internet, one often reads about the so-called “frost fermentation”. This involves digging as deep as possible in the fall so that the frost can penetrate the soil and “blast” it, so to speak. However, this method should be used with caution. Frost tillage should be used only in extreme emergencies, as it represents a significant intervention in soil life. It inevitably kills soil organisms that would normally be protected from the cold in the soil. These microorganisms and small animals are in turn extremely important for soil fertility and therefore indispensable for us gardeners!
Light soils, as the name implies, are easy to work with virtually all year round. They dry quickly, weeds can be easily removed and loosening is hardly a problem. This may sound tempting at first, but this type of soil also has its disadvantages. Sandy soils have a rather poor storage capacity. Water can easily seep through the coarse pores, which can quickly lead to drying out in summer. In addition, a soil poor in humus can hold nutrients poorly, they are easily washed out into the groundwater. However, the large pores have the advantage that the roots are always sufficiently supplied with oxygen and waterlogging cannot occur. In addition, light soils warm up more quickly due to the many air-filled cavities, so that early sowings are already possible.
Improve sandy soils
To make a sandy soil more fertile, you should first of all improve its storage capacity.
- Organic material is excellent for this purpose, it is worked into the soil in the spring. Mature compost or rotted manure can also be used here.
- Green manuring (e.g. buckwheat, mustard, phacelia, legumes) can also be very helpful. The plants can then be surface cut after some time and used as mulch. They serve to enrich the soil with nitrogen and humus. The humus serves as a reservoir and can thus help to better retain water and nutrients in the soil.
- A permanent layer of mulch not only helps enrich humus, it also reduces evaporation and protects the soil from drying out too quickly. The decaying organic material also provides food for soil life, attracting earthworms, for example.
- Mixing in finer soil particles also has a positive effect on the storage capacity of light soils. Loam or clay powder, for example, are suitable for this purpose.
- To reduce the leaching of nutrients, you should add them in the form of poorly soluble fertilizer. The goal in fertilizing is to feed not only the vegetable plants, but also the soil life. Poorly soluble fertilizers are mostly made up of organic material and must be decomposed before the plants can absorb the nutrients. This is exactly the point! If you use mature compost as an organic fertilizer, for example, the soil organisms break it down into its components and make the nutrients it contains available to your vegetable plants. The microorganisms are not neglected here, because they can also feed on the organic material. Also suitable are horn meal, horn shavings, bone meal, wood ash and manure from poultry, horses, cattle or other animals. Chemical fertilizer salts, on the other hand, are bad for plants and soil life in the long run. They are very soluble in water and are therefore absorbed directly by plants, even though they may not need the nutrients to that extent. They can quickly become over-fertilized, making them more susceptible to disease. Excess fertilizer is also more easily leached into groundwater, contributing to eutrophication. Aside from that, this fertilization method doesn’t provide food for the soil organisms, so they will “starve” in the long run and you will have to fertilize even more afterwards.
- When using plant slurry, it is better to fertilize less and more frequently, otherwise a large part will seep away. When making liquid manure, you can also avoid removing the plant remains through a sieve. The semi-decomposed plant material makes excellent mulch and can be utilized by soil organisms.
- Sandy soils are naturally slightly acidic, but the pH should never drop below 5.5. If a test shows that the pH is too low, you can raise the soil pH by adding lime (e.g. dolomite). Otherwise, too acidic soil can have a negative effect on your crops (e.g. blossom end rot in tomatoes). Tip: indicator plants can give an indication of the soil pH.
To give you a compact overview, in this article we have gathered all the common methods of soil improvement. There are many ways to make your soil more fertile, which does not mean that you have to use them all. You can simply choose the measures that are easiest for you to implement. You will soon realize which ones will help you succeed and which ones will not. The most important thing, however, is to better understand your soil and the life in it!
I have 30 years of experience and i started this website to see if i could try and share my knowledge to help you.
With a degree a Horticulture BSc (Hons)
I have worked as a horticulture specialist lead gardener, garden landscaper, and of course i am a hobby gardener at home in my own garden.
Please if you have any questions leave them on the article and i will get back to you personally.