In our last blog, we looked at how water and soil interact in assuring the success of your permaculture property. In this post, we’re going to take a look at how you can revive the soil ecosystem of a depleted suburban lawn as the first step toward creating your food forest.
When we began creating our permaculture homestead in Calgary, the front yard looked exactly like every other yard in the neighbourhood: a monoculture grass crop growing in poor, highly compacted soil. But we were already envisioning our food forest: a biodiverse, self-sustaining ecosystem growing delicious, nourishing food to sustain our family and serve the community.
To achieve that vision, we needed to build it, literally, from the ground up! And we wanted to provide all the components we’d need to support the food forest, in the food forest.
We began by sheet mulching and composting to establish the soil system. Next, we strategically selected plants to provide the nutrients and conditions our food crops would need….and just three short years later, we were already seeing the difference! The soil was starting to clump and form aggregates, and we were seeing bugs, worms, and other creepy-crawlies beneath the surface.
How could this happen so fast? When Rob was apprenticing at permaculture pioneer Geoff Lawton’s Zaytuna Farm in Australia, he learned the “chop and drop” technique: growing a cover crop, then chopping it to the ground to release its nutrients. It’s a highly efficient way of fast-tracking healthy soil development without chemical amendments.
Rob explains the principles of chop and drop in the Avis food forest in Calgary.
Of course, you could use this technique with just about any cover crop: all plants absorb nutrients and release them back to the soil when they’re cut and mulched, or die and decompose. But the real magic comes when you stack functions, strategically selecting your plants for the ecosystem services they’ll provide in your food forest as well as the nutrients they provide.
So, for example, we planted a small pear tree adjacent to cover crops of rhubarb and comfrey. These two played important roles in our pear tree guild: the comfrey is both an insectary (attractive to pollinating insects and birds) and a dynamic accumulator: its long taproot dives deep below the soil, absorbing calcium, magnesium, phosphorus, potassium, and other minerals which are stored in its large leaves. Meanwhile, the giant, funnel-shaped leaves of the rhubarb act as a water harvesting system, while storing calcium, potassium, and other minerals mined by roots that can extend 18” deep.
Once the comfrey and rhubarb reached maturity (and were crowding the pear tree), Rob cut them down, chopped their stalks and foliage into mulch, and piled that around the tree’s roots. The tree gained light and air, while the decomposing mulch released the nutrients that had been stored in the cover crop foliage.
So what do you look for in choosing cover crops for your food forest? Consider the functions you want these plants to serve:
Shading the soil: these are large-leafed plants like comfrey and rhubarb, as well as borage, burdock, Swiss chard, and others. They all have taproots to plumb the soil, and store minerals in their leaves while they shade and cool your food-forest floor.
Providing mulch and nutrients: You can chop and mulch both large-leafed and grassy grain cover crops to gain the nutrients from their leaves. Buckwheat, for example, accumulates phosphorus and potassium, making its leaves an ideal mulch for potatoes. Other cover crops, such as beans, peas, or clover, release nitrogen to the soil through nodules in their roots as they decompose.
A buckwheat crop in flower.
Contributing to the soil structure: All cover crops photosynthesise carbon dioxide and store it in their foliage and stems, exuding carbon to the soil structure through their roots as a form of sugar. This feeds soil microorganisms, whose activity supports healthy soil aggregation. Grains such as buckwheat and ryegrass are particularly useful in this way, with their thin, densely networking roots.
De-compacting the soil and improving bioactivity: The real heroes here are “biodrilling” plants such as Daikon radish, whose roots can penetrate compacted soils to a depth of six feet or more. As the roots die back, microorganisms feast on them, opening space for air and water to restore a healthy soil ecosystem.
Full-sized Daikon radishes, freshly harvested,
These are only a few of the cover crops you can use to revive depleted or compacted soil and guarantee the success of your forest garden, without the need to schlep in bags of fertiliser and other amendments…never mind the environmental cost in energy and pollution!
Want to learn more about cover crops for your forest garden? Check out Rob’s video on how he laid the groundwork for a client’s ¼-acre food forest with a “kill crop” of buckwheat, pea and rye grass:
To get you started on your food forest creation journey, check out our other post, How to Design a Permaculture Food Forest.
And be sure to sign up for our newsletter HERE, so you’ll be the first to hear about our upcoming, brand-new Food Forest course!
