The foundation of all growing plants in an organic system. Soil is what actually grows plants by providing a living biological matrix. This biology is critical to what we can grow. Most academic courses cover the chemistry and physics of soil but ignores the biology. We are about to cover all three.
Types (The Physics)
Soil is divided into different types a few ways. The first is by particle size. These particles are created by the actions of weather, wind or water, frosts and thaws and under glaciers.
This is the coarsest of soils. It will drink water like a camel. On the other hand it is free draining. It’s a matter of perspective. It can also be improved and made
This is the ultimate soil. It holds water, it drains as required. Plants love it and if you have it, cherish it.
This is made up of the smallest of particles. If worked wet, it turns rock hard. But we do not “work” any soil, do we? We are no dig gardeners.
In some senses the soil type doesn’t matter. By growing above the soil, or extending the soil up, so to speak, we ameliorate the effects of the soil type. Over time the organic matter rich material we use to create our raised beds has an effect on the underlying soil type.
This can happen much more quickly that would be expected. My first successful raised bed adventure involved putting goat bedding over cardboard on top of yellow, biologically sterile, sandy soil. Eighteen months later when we moved house, I dug up the raspberry canes to discover a friable, rich, worm filled, black loam. Further excavation revealed this change had penetrated to a depth of about 50cm (20 inches). All in eighteen months, one winter was droughty and the beds held water and crops kept growing.
Currently I’m on clayey loam. The beds will be investigated once the eighteen months are up and I can see what’s happened. I don’t have goat bedding, which I think was the secret ingredient, so I’m using compost and chicken bedding. If you check the table in the “Manures” module, you can see this is different from most other manures. Results to be published as they come in.
pH (The Chemistry)
Soils vary between acidic and alkaline. This affects the uptake of nutrients in some plants at some levels of pH. This is important but may not be as important as many people think. I’ll get to that in the No-Dig Implications.
|4.5 to 5.0
|5.1 to 5.5
|5.6 to 6.0
|6.0 to 6.5
|6.6 to 7.5
|7.6 to 8.0
|8.1 to 8.5
|8.5 to 9.0
Acid Loving Plants
- Sweet potato
Alkaline Loving Plants
- Brussel Sprouts
Organic Matter (The Biology)
This where the biology comes in. Anything that is or was once alive will be of benefit to the soil. This can be taken to extremes but most not be. Covering an acre of land with deceased cattle would eventually do the soil good but the process would have many negative effects. Spreading a handful of blood and bone per square metre would be more useful. Similarly, spreading a layer of wood chips will have a benefit but it may take a few years to have an effect. All these options will be discussed below.
Compost is not a natural process. It requires the careful construction of a pile of organic matter in a fairly strict ration with plenty of moisture to ensure a biologically active process. Thye heating kills pathogens and seed viability. As much soil can be created through composting in a year as Nature makes in a century. (Journey to Forever)
Vermicompost is the material left after it has been consumed by compost worms. Technically not a compost more the droppings of worms, it never reaches the temperature of hot compost. It may still contain weed seeds.
Vermicompost can be used neat, placed directly on garden beds, used as a seed raising mix or converted into a tea. (There will be a complete module of liquid fertilisers coming later in 2020.)
Vermicompost tends to sweeten soils over time, especially acid soils moving them to a more neutral pH. It doesn’t seem to affect alkaline soils.
Mulches are the prefered tool of Nature. Think forest floors, deciduous or evergreen. Layer upon layer of organic matter, protecting the living soil. Moderating the temperatures during the extremes of Summer and Winter, mulches both cover and feed the soil. They take much longer to decompose than the compost process mentioned above but they do represent the evolved solution from 500 million years of forests on the planet.
You have many choices when it comes to mulches: straw, hay, leaves, woodchips, slashed cover crops, shredded paper, wet cardboard, unwashed sheep’s fleeces, collected coffee grounds. You get the picture. The materials need to have been alive, capable of protecting the soil from direct sunlight and rainfall and let water in.
These are specifically formulated liquids added to the soil, the mulch, fruit trees and the leaves of growing vegetables. These are made using compost, vermicompost, manures and even weeds. These are soaked in water, with or without aeration. On a small scale, aquarium aerators work well. On the whole, an aerated liquid works better, smells better and is more pleasant to handle. There is a module on this entire process in the pipeline for later in 2020. There are also commercial options on the market. These tend to be based on seaweed or on the shredded bodies of invasive species of fish harvested in the clean up process of local waterways. Always check the labels to be sure of what you’re adding to your food producing gardens.