Perma-thoughts, 2

Here's an example of how my Permaculture course has changed my perspective on elements of the Patch:

On the northern boundary we're establishing a windbreak against hot, drying winds. At the moment, this consists of 15 Flinders Ranges wattle saplings. All but one are doing well, and should start to be effective in the next 24-36 months. I was quite pleased with this idea when I first thought of it: 'Good idea to create a microclimate, Steve!' I thought.

Will eventually be a windbreak: 15 tiny wattle seedlings , Aug 2011

Now, applying some Permaculture principles, I can see ways to make it a whole lot better:

Principle: Build diverse, stable ecosystems.

OK, a 15 x 2 metre windbreak (eventual mature size) isn't exactly an ecosystem. But what if I planted sheokes on the leeward side of the wattles, and grew a small-leafed (because not rampant) hardenbergia up the sheokes when established, and dug a swale to catch water runoff, and sowed the bank of the swale with dichondra and native violets, and planted blueberries in the lee of the windbreak? And put logs in the swale to provide habitat for lizards and amphibians?

Would this be an ecosystem, or just a collection of plants and landscape features? Let's have a look:

The wattles and the sheokes together will make a more effective windbreak; both are nitrogen fixing. When they are cut back (mulch for the veg beds), some of their root mass will also die off, making nitrogen available to the soil. Hardenbergia is also nitrogen fixing, so we have three plant species improving the soil. Blueberries on the leeward fringe of the windbreak will benefit from the added nitrogen, and also the acidic environment provided by the mulch of sheoke needles.

All of these are flowering plants and will provide forage for bees and nectar-eating birds. In addition the swale should become an ephemeral wetland, attracting the numerous frogs from the surrounding area - we're lucky to have two established wetlands to the northeast and northwest of the site.

So this begins to look like a functioning ecosystem, with beneficial interactions between the various species. In time further species would be introduced (or colonise by themselves) and it would become more diverse.

Principle: Every element of a design should function in many ways.

This is also referred to as 'stacking' functions. How does our windbreak fit in with this?

As envisaged above, it now serves the following functions:

• reduces the impact of hot, drying winds
• provides mulch for veg beds
• provides forage for bees (pollinators, suppliers of honey)
• provides habitat for insectivorous birds, reptiles and amphibians (pest control)
• provides fruit
• improves soil nitrogen
• improves water infiltration
• removes the need for mowing (saves labour)

Now, not all aspects of the plan will turn out as envisaged. For example, it may be that blueberries just won't flourish where I want them, so I would have to use other berries. That would tie in with other Permaculture principles:

Apply self-regulation and accept feedback.
Use small and slow solutions. (Otherwise referred to as incremental design.)
Creatively use and respond to change.

Soil

For the past couple of years I've been paying more attention to the soil in my garden – 'soil' is a short word, but what is it exactly?

Soil is an amalgam of tiny particles of rock with humus (decayed vegetable matter), fungi and bacteria. This provides a substrate for plants to anchor themselves in and a sponge to capture water, making it available to the plants' roots.

Soil contains a wide variety of nutrients which are essential to healthy plant growth, including the big three – potassium, nitrogen and phosphorus. Then there are the secondary nutrients calcium, magnesium and sulphur. Thirdly, there's a range of micronutrients: boron, copper, iron, zinc, chloride, molybdenum and manganese. 'Micro' because they are only present (and needed) in tiny quantities. They're also called 'trace elements'.

So far, so complicated. But we're not done yet. Not only do plants need all these nutrients in varying quantities, it appears that they also need the help of a type of fungus to enable them to digest their food. This symbiotic relationship is called mycorrhizal (fungus and root).

So there's a lot more to 'soil' than just some brown crumbly stuff. But how can I apply this knowledge practically in the garden?

Well, I monitor soil pH (acidity/alkalinity), because I know that it affects a plant's ability to take up nutrients. A pH test kit is quite cheap and easy to use. An excessively acidic (under 5.5) or alkaline (over 7.5) soil can be corrected by the addition of lime or sulphur respectively. I check the soil pH about once a year.

Other than measuring pH, soil care is fairly unscientific in my garden. I adopt a variety of approaches, hoping that they will all help.

• I try to get as much organic matter into the soil as possible, through the use of green manure (a crop which is grown, slashed down and dug in to feed the soil) and home-made and bought-in compost.
• I boost micronutrients through the addition of rock dust.
• Now that my worm farm is flourishing I can also add worm castings and worm 'wee' to the soil, hopefully boosting its population of beneficial bacteria.
• The organic mulches I apply, such as lucerne and pea straw, protect soil microbes and plant roots from overheating and desiccation, and add some carbon and nitrogen as they break down.
• I try to avoid deep digging, which brings sterile subsoil to the surface.
• I'm experimenting with the use of comfrey and lucerne - deep-rooted perennials - to recover lost nutrients from the subsoil.
• I don't sieve soil unless absolutely necessary, because it disrupts the soil structure and can produce a hydrophobic surface.
• I'm very careful about what I put in and on my garden soil. No detergents, no poisons like glyphosate (Roundup or Zero), which may harm beneficial bacteria.

As well as these basic measures, I've recently started to experiment with two new products which have come on the market: biochar and Bactivate, a bacterial fertiliser.

Biochar is the 'black earth' that is supposed to have given the naturally poor Amazonian soils great fertility, supporting intensive agriculture in pre-Columbian times. Basically it's charcoal, in a form which binds water and nutrients, making them available to plants and improving soil structure. Bactivate is also carbon based: it's pellets of coal dust coated with beneficial soil bacteria.

By the use of all these methods, I'm hoping to transform the rather poor, sandy and hydrophobic soil I inherited for my vegie patch into a rich, fertile growing medium. Comparison with other parts of the garden suggests that I've already made quite a bit of progress.

What I'd really like is the rich, dark soil of my mum's and stepdad's garden in western France. Come spring, the vegies in the Limousin leap out of the ground at an astonishing rate. However, it's taken probably 3,000 years of organic cultivation to make that soil, so I may have a way to go yet!

How d'ya like them onions?

Reliable spring rain followed by a mild start to summer has given us a superb onion crop this year: big, juicy and full of flavour. In a raised bed about 2.5 x 1.5 metres I've grown about 120 onions - 30(ish) each of Early Barletta, Long Red Florence, Heirloom Red and Creamgold - plus a few English spinach plants. The Early Barletta and the spinach have long since been harvested and digested, but I've just pulled the Heirloom Reds and the Creamgolds, and the LRFs are still going.

I thought disaster had struck when we got the heavy rains last week: all my lovely onions were sodden and I was convinced they would all rot!! Fortunately I keep some long rolls of Solarweave in the garage and was able to cover the onion bed on Tuesday, allowing the soil to dry out.

Creamgold, Red Heirloom and Long Red Florence

Through trial and error I've discovered that to grow onions in our garden I need to avoid mulching. Even the thinnest covering of lucerne or pea straw seems to lead to white basal rot which ruins the onions' flavour and keeping qualities.

No mulch inevitably means more weeding and watering, but a leafy cover crop helps to shade the soil until the onions are well established - hence the spinach. Once the bulbs are starting to swell, some low-growing weeds can be tolerated and may actually help to cool the soil and retain moisture.

I always find onions a bit of a worry - they occupy the sunniest bed in the garden for 8 months of the year, so I want a good return on my investment. I often get it wrong: two years ago I left my newly harvested Creamgolds out to cure in the sun - on a 40 degree day. We came back from the beach to find the onions well on the way to becoming roast onions. Disaster!! There was no way I was going to chuck my precious crop out, so I fired up the barbie and spent the next two hours chopping and frying onions with tomatoes. That all went in the freezer and kept us in pasta sauce for a few months.