Good soil is central to food production, and therefore to human life. It is necessary for strong, healthy plants that can feed us well. Modern industrial agriculture makes huge demands on soil and there is widespread evidence of soil erosion and a slow decline in soil fertility. Improving you growing soil will not only improve the crops you grow, it is a crucial contribution to healing the planet.
Good growing soil has three characteristics: rich biological life, good structure, and readily available nutrients. A range of simple tests can be done at home to measure the biological life and structure (see The Permaculture Association Soil Test Handbook).
Biological life
Good soil has rich biological life ranging from billions of things you can't see like bacteria and fungi to big things like worms and beetles. The biological life in your soil creates the soil through its digestive activities and binds the soil together. Whatever kind of soil you have, improving the biological life will improve it; in sandy soil, biological life will bind it together, improve the amount of water it can hold, and keep nutrients in the soil. In clay soil, biological life will breakup the lumps in your soil and free up trapped nutrients for plants to use.
Soil structure
Good soil has a number of structural features; it lets water through when weather is wet and holds water when weather is dry; it consists of a number of small, loosely packed balls (crumbs) which allow plant roots to pass between them while anchoring them securely, it is deep enough to allow plant roots to grow extensively, and it is not easily eroded by water or wind. Soil naturally forms layers; the organic layer, the top soil, the sub soil, the bedrock. Together, these layers are termed the soil profile.
Nutrients
Plants primarily feed on energy from sunshine (photosythesis). However, to be strong and healthy they also need a number of minerals from the soil; soil nutrients. Soil nutrients are difficult to measure without using a lab, so you may want to submit a sample to a lab to find out the balance of nutrients in your soil. However, if you feed your soil properly, look after its biological life, and ensure it has a good structure, it will generally feed your plants well unless it is lacking in a specific mineral.
This content is derived from work created as part of the GROW Observatory, which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 690199.