Soil building is one of the most important aspects of regenerative land stewardship. Soil rich in nutrients, organic matter, and beneficial microorganisms supports healthy plant growth, which in turn, supports a thriving ecosystem.
First, soil is the thin layer of material covering the earth's surface that is formed from the weathering of rocks. Healthy soil consists of mineral particles, organic materials, air (gas), water, and living organisms -- all of which interact slowly and consistently.
There are really only two options for soil building: 1) importing the soil or 2) improving the soil that you already have. The latter is where we use our knowledge of soil biology to regenerate the soil, or bring it back to life.
In regenerative (or permaculture) practices, we try to replicate nature's biological richness for whatever we are attempting to grow. For instance, the weight of fungi in forest soil is much greater than that of the bacteria dominated soil beneath annual weeds on bare ground. Grasslands tend to have an equal distribution of both. So whether you are trying to create a healthy pasture, a self-fertilizing food forest, or just a productive home garden, you must try to simulate the conditions where the intended plants are initially found.
What are some common regenerative practices for building soil?
1) Don’t disturb the subsoil and encourage biological tillage
The undisturbed subsoil (or soil right beneath the topsoil) lets the earthworms dig their tunnels and provides aeration and drainage while their excretions bind together to make soil crumbs. They are essential in healthy soil structure and replace mechanical with biological tillage. If you don’t compromise earthworms, microbes, and other soil organisms through soil disturbance, they can perform much of the tillage needed to create and maintain loose, fertile soils.
But what if your soils are biologically dead? In this case, these microbes have to come from somewhere. This is why we need to feed soil with biologically-active, decomposed organic matter that is rich in beneficial microbes – the compost.
2) Bring your soil to life with compost
Good compost supplies both the organic matter for soil building and the fertilizer for the crops. Most importantly, it is packed with soil organisms that trigger biological activity. It inoculates your soil with microbes that will digest nutrients present in the soil and feed your plants.
Compost is the key ingredient for building and maintaining healthy soil. Because of its unique characteristics, compost cannot simply be replaced with manure, natural fertilizers, or green manure.
3) Maintain organic matter with mulch
Once you have your soil biology in place, you need to feed it so that it can feed your plants. There are several ways to maintain soil organic matter from grass clippings, leaves, straw and cover crops, to compost. The actions of the earthworms, bacteria, fungi, insects, and organic matter will slowly break down and release nutrients into the soil for whatever you are growing.
In large-scale market gardens, grassland/pasture situations, food forests and permaculture orchards, soil building efforts should include:
- Crop rotation to mimic diversity
- No till practices
- Keeping your soil covered with perennial cover crops
- Planting diverse perennial cover crops
- Rotating livestock between grazing areas
- Using chop and drop practices
- Allowing cover cropping and woody mulching
- Inoculating your soil with mycorrhizal fungi
- Using woody mulch to feed your fungi
- Creating self-sustaining fertility through nitrogen-fixing plants
As you build soil in these regenerative ways, you return nutrients and organic matter to the soil which restore your soil's fertility and productivity.