The Gordon Gnohm

Play along at home, read Future Farmer in The Braidwood Bugle every Wednesday. 

Passive Land Hydration Pt7 Permaculture Swale

In the late 70’s David Holmgren collaborated on an idea with Bill Mollison. Their concept was building on the pioneering work of innovative Australians before them. Focussed on hydrating landscapes and furthering the idea, to provide habitat for permanent food production systems. They went on to describe a design philosophy for this mission and called it Permaculture. The corner stone of this design work is the Swale. 

A Permaculture Swale is the ultimate realisation of a Passive Land Hydration System, by stacking useful elements in harmony, to create a functioning ecosystem. The other techniques previously discussed allow for infiltration of water but not much else. 

PA Yeomans started by cutting a contour furrow to let the water into the earth. Peter Andrews makes trenches with little to no mound on the downhill. The Permaculture boys took this idea and compounded it to allow a connection between agriculture, ecology and design. To assist the production of grass, trees and tucker to be more like Nature, rather than the unsustainable modern practice of annual monocropping. 

A Swale does more than hold water, it provides many benefits. It is difficult to see for the casual observer, but in a few years the transformation will be undeniable. Here are the basics.

Water

As with the other Passive Land Hydration Systems we have discussed, holding water on contour for soaking across your property is the key. This water soaks into the mound then travels slowly downhill in the soil. Moving through the soil, rather than across the surface, is essential to minimising topsoil loss. 

Shade

The greatest threat to water in summer is evaporation. Sun beating down on the surface of your water will quickly transform it to vapour and send it back to the sky. The same will happen to the water in your soil. Shade is the best way to prevent water loss, so plant trees on and around your Swale. The shade will increase every year until summer sun is no longer a threat, and you can maintain productivity longer. 

Wind Abatement

Trees are the best way to slow wind across your property. A woodland setting is better at slowing wind than an open paddock and Monga NP has little wind. What to plant around a Swale is super impactful on your future productivity and wind protection. This is where Ecosystem study assists planting decisions. I plant all kinds of trees, deciduous, evergreen, natives, exotics, fruit, berries, vines and vegetables around the Swale, stacking enough form and function so the system can sustain itself and create surplus. 

Under and overstorey trees need to exist in harmony, giving support to valuable food or grass production and providing protection from frost and sun. A set of trees across the property, covering different heights, shapes and densities will provide a better wind break for your paddocks than the popular notion of 2 rows of dense trees planted on boundaries.

Habitat

Shade, water and mulch, in the form of branch and leaf drop, is the best way to provide natural habitat for microbes and fungi. The planting of trees, shrubbery, vines and vegetables create habitat for critters, and for humans too. The trench will become filled with grass and reeds creating habitat for frogs, yabbies and dragonflies. 

The trees will become haven for birds to feast on insects. When they arrive, and depart, they tend to make a valuable deposit. Add that to the moisture available in the soil and a safehaven for microbes is created. They will thrive and process compost for you while you sleep.

Once the pioneer critters are present in your ecosystem, the habitat will be ready for more apex predators to arrive. Think microbats, praying mantis, and owls. Every year a new critter will bloom and be met with a predator to control the numbers. That’s how it is in Nature, seems logical to have it around your home too.

Nutrient

Leaf fall will find its way into the trench to combine with spent reeds and grasses. This is a literal smorgasbord for microbes to feast and make compost for you. This nutrient is collected and processed in the Swale without any input from you. 

If you want to get involved, you can rake the resource from the trench and apply it to the mound. Adding to the mound and/or the trench for the first few years will assist the system to establish faster.

The nutrient in the trench will soak into the mound and slowly make its way downhill offering food to the roots of your plantings. In the soil, not on the soil. Nutrient rich water flowing downhill in the soil is a great way to grow lush grass. Perhaps I can have a milking cow out here after all… Gotta dream.

Initially, Permaculture was developed to rehabilitate broken landscapes, to provide food and resources for the residents and ultimately offer permanence of habitat for humans to thrive where there was no hope. Since then, Permaculture and Swales have been used to solve many human problems, and next week we will discuss some creative uses.

This Week

A welcome note in the garden is the return of the Eastern Spinebill, happily zipping through the garden dipping into nasturtium flowers. The call of this bird is electrifying as it rings through the space. 

Some hefty moths (perhaps Bogongs) have been arriving over recent weeks and are a great protein feast for our Microbats before they hibernate. Mosquitoes are still around, but not as tasty and nutritious as moths. 

No frost in our Garden microclimate yet, plenty of heavy dew and too much rain, adding to the thermal mass in the earth keeping soil temp up. The basil did not enjoy 2 weeks wothout sun and excess water, resulting in mouldy leaves.

Tomatoes are slowly ripening on the vine, not enough to make it worthwhile for us anymore. The last vine is being left as decoy food for the rodents. They seem to be leaving everything else alone and eating only tomatoes.

After 2 weeks of Skywater and gloom the tanks and Swales are full and the garden is saturated. It’s time to apply some sugarcane mulch. Get it on thick around 100mm. This fresh covering will also keep your soil temp higher, longer. My garden beds are still around 14-15C, what’s yours?

Happy Mulching,

Stay Awesome.

The Gordon Gnohm

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