Gardening can be energy efficient and enjoyable if we undertake the right tasks and share the work with nature.
We often overlook how amazing nature really is. Plants have been growing on this planet without human intervention for the past 460 million years, so clearly nature has evolved some rather remarkable systems to support plant growth.
If we want to work with nature, we need to ask ourselves how we can support these existing natural processes that support plant growth, and leverage them for our benefit.
TEAMING WITH NATURE
In the ecological design system of permaculture, we aim to use biological resources to do work or conserve energy. If we can use a plant or animal to perform a certain function or task, rather than our own eﬀort or non-renewable resources such as fossil fuels, this is our preferred approach.
So what do we need to garden more sustainably? Conventional gardening and agriculture are energy and resource intensive, but permaculture is not; it’s information and imagination intensive instead. If we want to work with nature, we need to first understand how natural systems work and then get creative.
In permaculture, one of the central teachings is “feed the soil, not the plants”, because it’s physically impossible to naturally feed a plant directly.
We’ll look at the science shortly. By understanding how plants feed, we can give them precisely what they need to achieve optimal plant health and vigor.
THE SOIL – FOOD WEB
Soil is often mistakenly considered to be nothing more than an inert mineral substrate, a mix of sand, silt and clay of varying proportions, which serves no purpose other than to anchor down plant roots and to hold water and fertilizer. Nothing could be further from the truth.
Mineral particles make up only around 45 per cent of the overall volume of healthy soil. A critical portion of soil, around five per cent, is made up of organic matter; four per cent of this is humus, essentially decayed organic matter.
The rest of the organic matter is actually living, comprising 0.5 per cent roots and 0.5 per cent soil organisms.
And the other 50 per cent? It should be no surprise that healthy soil is 25 percent air and 25 per cent water, which is there to keep soil organisms and plant roots alive, of course.
Soil is one of the most complex ecosystems in nature, and it’s the most densely packed ecosystem of all.
There are more organisms in a tablespoon of healthy soil than there are people on the planet.
Soil organisms include bacteria, actinomycetes, fungi, yeasts, protozoa, algae and nematodes, as well as arthropods and insects, including earthworms.
All the soil organisms interact with one another and with plants and animals in a complex web of ecological activity we call the soil– food web.
There’s a lot of life in the soil and it’s critically important as it supports all terrestrial life on the planet.
It’s not appreciated simply because most soil organisms are invisible to the human eye, and soil ecosystems exist underground.
FEEDING THE SOIL
Plants feed oﬀ anything that was once alive, but they can’t access the nutrients directly. The organic matter first needs to be broken down by the organisms in the soil–food web, then converted into a form that plants can use.
That’s how nature feeds plants, and it’s the only way, in fact. So when we feed the soil, we feed the soil–food web, which in turn feeds the plants. It’s a collective eﬀort.
Synthetic mineral fertilizers, which didn’t exist before the 1900s, work quite diﬀerently. They’re usually water soluble and force-feed plants whenever they draw in water.
Being mineral salts, synthetic fertilizers are quite damaging to soil health as they desiccate soil micro-organisms and cause a loss in soil microbial numbers and biodiversity.
THE ROLE OF SOIL ORGANISMS
Soil bacteria can form beneficial symbiotic relationships with plant roots, the best known being the nitrogen fixing Rhizobia bacteria associated with legumes.
Similarly, soil fungi form beneficial relationships with tree roots, helping them access nutrients.
Mycorrhizal fungi can extend the surface area of the roots by as much as 400 times, assisting trees with the absorption of water and nutrients, making them more resilient to heat and drought conditions.
Soil organisms carry out many important functions, such as:
- Decomposing organic matter and nutrient cycling
- Improvement of soil structure to aid water and air movement through
- Control of pests, diseases and parasites
- Soil detoxification
- Enhancement of plant growth
KEEPING THE SOIL ALIVE
Soil organisms require a dark, moist environment to survive, and they need a continual supply of organic matter for food. We therefore need to cover the soil, prevent it from drying out and keep adding organic matter to fuel
Here are some practical ways to improve soil health:
- Feed the soil with organic fertilizers at the start of spring and autumn.
- Grow cover crops, dense perennial groundcover plants grown close together, as a living mulch.
- Sow warm- or cool-season green manure plants, fast-growing annual crops that add organic matter and nitrogen to the soil. Chop-and-drop them on the soil surface or dig them in when they first start to flower.
- Practice no-dig or low-till gardening to keep soil disturbance to a minimum.
- Rotate annual crops to avoid nutrient depletion and build-up of pests and diseases.
- Amend the soil to improve drainage, water-holding capacity, soil structure and nutrient retention by using materials such as compost, worm castings, zeolite and biochar.
- Keep the soil covered with mulch to protect it and retain moisture.
Inoculate the soil with beneficial microbes using compost teas or worm farm leachate.
Sensible gardening should be about caring for both soil and plants equally. The soil–food web is intimately connected to plant roots, and soil organisms can do a far better job of supporting our plants than we can – that’s what they do best.
Plants growing in healthy soils are better able to resist drought, pests and diseases, and are more resilient in general.
By supporting the soil biota, we can work with nature to maximize the success of new garden plantings and ensure that our existing gardens are maintained at their healthiest and best.