“You can solve all the world’s problems in a garden.” ~ Geoff Lawton
Soil is not just a “growing media” for plants: if we didn’t have soil, we wouldn’t exist (and the same applies to other species). Our soil is alive and has been in an ongoing process of creation and transformation since millennia…soil is made of “parent material” (rocks, lavae, etc.) and the interaction with many forces such as climate, water, wind, animals and plants, microorganisms and time.
If you want to grow an edible garden, you need to start with the soil: you may have a big yard or a plot in a community garden, or you may need to grow food in containers in a balcony. In either case, you’ll need some soil.
If you are lucky enough to have healthy soil in place, continue with “Observing & Interacting” to make sure you understand your soil.
If you live in the city and don’t have access to soil, check “Home-made soil for urbanites” for soil recipes.
In any case, your soil will need:
- Food to keep the microorganisms happy: this creates a healthy cycle that allows your plants (and therefore, the microbiome in your gut) to be strong and healthy and produce better yields. The best way to “feed” your soil is by adding organic matter from various sources. See “keeping your soil happy” for details.
- Water: the soil “people” need water to live and continue their amazing magic
- Air: soil is made of around 50% of solids (these are around 45% minerals represented by sand, silt and clay in different proportions) and around 5% of organic matter, the 50% left is divided as 25% air spaces and 25% water (this is in an “ideal” soil for growing food): air spaces allow for better water and nutrient exchange and retention and are also necessary for root systems to expand and access water and food. Air spaces are the result or an interaction between soil structure and the many microorganisms in it.
- Protection from compaction: apart from designing your garden in such a way that people, pets or other animals may not stomp over it all the time, compaction can be avoided by adding the right amount of organic matter. In a container, you may also want to balance the air spaces by adding coarse sand or gravel. I particularly don’t like perlite or vermiculite but those are options to prevent the compaction and enhance water retention. These materials are usually present in nursery “potting soil”.
- Protection from evaporation: water evaporates because the soil is exposed to the sun or because the soil is allowed to drain too fast in a container. To avoid fast evaporation you can add mulch, plant polycultures and create a self-watered system with spikes or ollas (in raised beds) or one container inside another with some type of pipe or stream to allow for the water to circulate.
- Protection from undesirable species: bare or unhealthy soil usually attracts “weeds” and pests or diseases. The reason for this is unbalance: nature is always trying to “fix” unbalances and this is being accomplished by species that may not be welcome in our garden. The best way to protect the soil is to keep it covered by a variety of crops and mulched as naturally as possible. Check “mulching” for details.