In a manner of speaking, soil is soil. But what makes great garden soil? Most soils contain 5% or less organic matter. The best garden soils are rich in organic matter and biological activity.
Organic matter makes garden soils workable, a good texture, and full of plant nutrients. Organic matter is where most of the biological activity takes place.
Biological activity within soil provides ways for organic matter to replaced or increased. As well, it is activity at the microscopic level which allows nutrients to be taken up by plant roots.
Adding Organic Matter to Soil
The best ways to add organic matter to soil are through mulch and compost. Add both generously throughout the year. Adding a layer of leaves or straw at the end of the growing season can give your garden soil a boost of organic matter in the spring.
Compost comes with active bacteria included and sometimes worms and other beneficial insects.
Compost Tea and Charcoal
Ways to increase biological activity in garden soil:
- Compost tea or worm tea – Adding compost increases garden soil biological activity. Compost tea or worm tea can do the same. Compost tea and worm tea are made by oxygenating the compost to increase the populations of good bacteria. Spray worm or compost tea directly on plants.
- Charcoal – Charcoal provides great habitat for soil microorganisms. These microorganisms help create the chemistry that allows plant roots to uptake nutrients.
- Worms – Whether the red wiggler, composting variety or average garden variety, worms aerate the soil. Looser, more oxygenated soil plus worm castings equals good environment for biologically active soil.
The Best Soil Recipe
If your soil is very compacted, rocky, clayey, sandy or low in organic matter, you may want to consider raised beds for your garden. Using a raised bed allows you to create great garden soil right from the start.
Any soil mix can be used in a raised bed garden. The best soil recipe will contain lots of organic matter and a good environment for soil microorganisms.
The square foot method for garden soil for raised beds is 1/3 compost, 1/3 vermiculite, 1/3 peat. Another garden soil recipe is 1/3 soil, 1/3 peat, coir, or bark mulch, 1/3 compost.
To any of the above recipes or any garden soil mix the following can be added:
- Charcoal – as discussed above.
- Manure – it’s best to compost it a little first, especially chicken manure.
- Ashes – add sparingly, like a fertilizer. Ashes provide phosphorus.
Even the best garden soils will become depleted with time. Be sure to add compost, mulch and organic fertilizers throughout the growing season.