Twelve simple food-gardening practices

I have grown vegetables for many years and read many books on the subject, but until half a year ago I was not aware how central microbes are to growing vegetables and fruit that are nutrient-rich.  This blog post briefly discusses why soil microbes are important and then offers a range of simple things food-gardeners can do to improve the quality of the fruit and vegetables they grow.

Microbes, or micro-organisms, the microscopic life forms in the soil in which you grow your vegetables and fruit, are hardly ever mentioned in gardening books, magazines or TV gardening programs, yet their presence, absence or abundance makes a major difference in the health of the fruit and vegetables you grow.  This is because healthy plants have a close physical relationship, a symbiosis, with the microbes around their roots, a relationship that is beneficial to both plants and microbes.

Gardeners feed their plants manure, compost, fertilisers, mulch and minerals and assume that plants 'eat them somehow' and grow and prosper.  However, many gardeners, even many of the experts, do not realise that microbes make all that food available to the plants.

We are lucky to have Letetia Ware in southern Tasmania as an ardent advocate of this thinking.  In a recent workshop on the subject of soil biology she discussed many things to do with microbes, some easy and obvious, some more involved.

Microbes is a term used for an incredible variety of very diverse micro-organisms.  What is a very involved science all on its own can perhaps be summarised by saying that in healthy soil there is a micro-world that can be compared to the unspoilt wild worlds of Africa.  There are many varieties of animals that graze (bacteria and fungi) and there are many varieties of animals that eat other animals (protozoa and nematodes).

In soil that has no microbes, in other words a dead soil, a plant will struggle to access any of the manure, compost or fertiliser added to it because it is not in a form that is readily accessible.

In soil that is rich in microbes those microbes make food available to plants in a form that is readily accessible and in return get food from the plants that the microbes need to thrive.

Based on this information, people such as Dr Paul Stamets ('6 Ways Mushrooms can Save the World'),  Dr Elaine Ingham ('Soil Food Web International') and Jeff Lowenfels ('Teaming with Microbes') and others have developed methods that give microbes a central place in the growing of nutrient-rich food. According to their methods you don't feed your plants, but you feed your microbes, and if you feed them well, your plants will thrive and provide you with nutrient-rich food.

12 simple food-gardening practices

If you see the health and diversity of microbes in your soil as central in growing nutrient-dense food, Letetia recommends you adopt some or all of the following 12 simple food-gardening practices:

• Compact your soil as little as possible by walking over it as little as possible, by not having animals walking over it a lot, and by not using heavy machinery.

• Adopt the no-dig approach.  Turn, till and dig your soil as little as possible so you minimise damaging or killing soil organisms.

• If your soil is really bad or compacted, disturb it in a major way once (aerating, digging, improving drainage, adding major amounts of compost etc.) and then go back to the no-dig method.

• Never leave your soils bare.  Conventional wisdom has it that you leave soil bare until it warms up in spring.  Mulching all year round prevents the top layer of soil from drying out and exposing microbes to heat and sun.

• Never let your soils dry out.  Keep your soils moist, but not wet.  Dehydration kills aerobic microbes.  Wet soil causes anaerobic microbes that kill plants to multiply.

• This one is simple if you are not dependent on town-water: if you can, water your plants with fresh non-chlorinated water, instead of mains tap water, because chlorine harms many microbes.

• If you want to add lime or other materials to your soil directly add small quantities a number of times rather than a large quantity once, so the impact on microbes is minor rather than major.  In addition, if you apply manure straight to your soil, it needs to be aged, never fresh.

• It is much better to not apply fertilisers or manures to your soils directly at all, because their impact can be too harsh for your soil microbes.  Instead, have a compost heap (or two) and add all your manures and fertilisers to your compost heap.  Then apply the resulting well-matured compost (3 months old or older) to your soil.  Cover your compost heap with a shade cloth or carpet, so developing microbes can thrive in a moist environment.

• Add as much organic matter to your soils as you can.  Microbes love organic matter.  You can never have too much of the stuff.

• Try not to use chemicals to treat garden pests.  The chemical may give you a short-term win, but it may have a long-term negative effect on your soil microbes (and your own health).  Garden pests are often a symptom of a problem.  By focusing on good gardening practices and constantly improving your soil you will over time get rid of these problems and have fewer garden pests.  Some people are so strong and healthy they never catch a flu.  In the same way plants that are strong and healthy will be more resistant to garden pests.  It is thought that healthy plants send out different signals and taste differently and repel many garden pests.  The symbiosis between plant and microbes will create this health.

• Be aware that mulches and manures may come from non-organic sources and may have chemicals in them that are harmful to microbes.  Mushroom compost may come from non-organic sources and may have too many chemicals in it.  Sheep manure may have worming chemicals.  Where possible, get these materials from organic sources.  You can mellow the effect these materials have by only using them via your compost heap.

• If you make a new food-garden bed, cover it with mulch and don't use it for the first six (or more) weeks.  This allows the development of microbes that will be beneficial to your first crop.

Most of the dot-points above are simple to implement, but they can make a major difference to the health and diversity of microbes in your soil, and therefore the health and nutrient-density of your fruit and vegetables.  

You don't have to implement all these suggestions all at once to achieve a positive effect. Start with one or more of them, then add others later on, if they feel right to you.

Happy food-gardening!

(this blog post was published with Letetia Ware's agreement and feedback)