Reconstructive Earth Surgery
Having started my engineering career in the oil and gas industry my first experience with large earth moving machines was relatively negative. Whenever I had to employ them it was to bring down a swath of trees called a “cut line” in order to make way for a new pipeline or hydrocarbon processing facility.
Luckily for me, I discovered that we can employ earth moving machines with intentional design and with a change in approach we can have an astoundingly regenerative impact on our landscapes and ecologies.
Earthworks at Zaytuna Farm, November 2009
While at Zaytuna Farm I spent a lot of time face to face with a twenty-five ton excavator, a roller, and a bulldozer and I got to see how productive these machines could actually be. Geoff Lawton refers to permaculture earth moving as “Reconstructive Earth Surgery” which to some people may seem like a strange analogy. But if you think about the size of earth moving machine relative to the size of the planet, we can actually make incisions at a much higher degree of accuracy than brain surgeons and scalpels. Couple these machines with a science based design system and you have regeneration of landscapes being brought to a whole new level! Darren Doherety, another past teacher of mine, always says “Blue, Green, Brown”. This means fix the water cycle first (blue), get the fast carbon pathways going second (green) and lastly, carbon fixation (brown) will happen as a result.
Degraded and severely eroded creek
When dealing with degraded landscapes nature can usually repair the water cycle but it can take hundreds if not thousands of years. When we use earth machines to make sutures in the landscape we can provide the conditions to accelerate this regeneration to as little as three years.
The permaculture ethics of earth moving are quite simple. Similar to a good financial investment, the large movement of earth that has an energy return on energy invested is an investment you should make. How can an earth construct accomplish this? Well, it turns out that between 30-40% of the energy we use in society goes to pumping water and sewage around! Just by installing water storage at elevation we can supply all of our water needs without the need for pumps. In addition, these water storages can be used as fire breaks, fire fighting, irrigation, recreation, aquaculture, creating microclimate, creating habitat and aesthetics. Note that all of these activities currently consume additional fossil energy because of the way they are designed (or not designed).
The Main Surgical Earth Works
A swale is a water harvesting ditch on contour and has been used for centuries. This construct has to be built dead level with a soft mound so that it pacifies and infiltrates water. The mound has to be planted to prevent it from becoming compacted and holding water. Swales can also be described as tree growing systems built on contour or used in our gardens to passively harvest water and irrigate our plants from the roots.
A Swale (Water Harvesting Ditch) on Contour
The swale is a suture we can use in the prairies, on cattle and on grain farms to increase water retention, crop yield and biodiversity. The trick with farm integration is to contour strip forests for windbreak, sun shelter and use the additional foliage & timber for livestock forage, fuel, and construction materials.
Bill Mollison claims that we can put land under 25% forest without losing any productivity. If we think outside of the wheat field, forests can increase yields in numerous ways:
Wind shelter for crops increases yield and reduces evaporation
Wind shelter for livestock is a benefit as livestock can stop gaining and even loose weight in windy conditions, especially when it is cold or hot.
Contour strip forest can keep snow in the system longer, infiltrating water into the field
If polycultural forest strips are used they can provide their own sets of yields, like free range chickens, pigs, or other forest-loving animals.
Wood and timber yields can be harvested from the system if designed properly
Trees mine nutrients from depths not available to annual grasses and crops which keeps the field mineral rich. For instance, when the Asian rice paddies lost the forests at the top of their paddies, they had to start using fertilizers.
The Pond or Dam
A pond or dam is a surface water storage that can hold water at elevation and is built out of subsoils typically with a clay content greater than 50%. The clay content of your soil can be estimated if you can take a subsoil sample, roll it into a sausage and make a doughnut without it cracking. If you can do this, you have enough clay content! As water ecologies build topsoil at the fastest rate of any ecology on earth you can understand why permaculture designers often have an obsession for ponds and dams. On top of that, they can grow fish, fight fires, supply potable water, provide habitat, and irrigate crops. To increase the effectiveness of the ponds we can also integrate them with swales and increase their catchment area.
Diversion drains are used to direct water in a direction that you want it to go. We are all used to these types of constructs as our cities are built on them. Permaculture designers typically use these constructs on the sides of roads attached to ponds and/or swale systems. They are great at diverting water away from access and house sites where water infiltration could cause problems.
The Check Dam or Leaky Weir
A Leaky Weir Installation at Mulloon Creek, NSW Australia
The check dam is a construct that is typically installed into seasonal creeks, drainages that flow periodically, or draws that have erosion issues due to a lack of top soil and vegetation. They are placed in order to slow water, create a siltation field behind them and infiltrate water. These installations help to repair the water cycle rapidly so that plant life can come back to repair the soil. Bill Zeedyke is famous for his work on stream, creek repair, check dams (also known as one rock dams) and induced stream meandering. At Mulloon Creek Natural Farm, these features have been used with phenomenal results in conjunction with fencing of riparian areas to repair and regenerate a creek that had been destroyed by cattle and bulldozers in less than three years.
The Main Surgical Earth Machines
The excavator is a versatile machine that every designer aspires to own. It can climb slopes in excess of 35 degrees, and can perform nearly all of the major “surgical operations”. This machine is good at excavating, track rolling for compression of dam walls, building swales and diversion drains.
We sometimes decide to hire a small excavator to complete a job because of the lower per hour cost but larger machines can move more earth per hour and taking significantly less time for the same job. The larger machines can also do significantly more: while at Zaytuna Farm we hired a twenty-five ton excavator to install a large dam, fix a pond, build a road crossing, extend 2 swales, install two new benches for the new kitchen classroom and toilet block and repaired some road drains in less than a week!
A versatile machine that packs a lot of punch. I was surprised to learn that these machines can build ponds at a good speed, compact pond walls, build swales, diversion drains, and pretty much anything that needs earth moved. Now combine a dozer with an excavator and you have a weapon of mass regeneration! This is another one of those machines that pays to “right size”. Too small and your dam project will become a damn project, too big and you will pay too much.
This machine is used endlessly in Alberta for clearing snow, making roads, repairing road and flattening sites. Some people say that you need to have country that has lots of varied topography, but with the topography you loose options in design. Most topographically diverse land almost designs itself, but flat-ish land like we have here in the prairies offers endless opportunity. The grader brings a lot of that opportunity to life because of its ability to move copious amounts of land which equates to inexpensive earth works. Why dig a swale with an excavator when a grader can do it in half the time? In the prairies it is often a grader and dozer game with the occasional excavator!
The Sheeps Foot Roller
The Sheeps Foot Roller is a steamroller-looking machine that has protrusions that increase compaction dramatically. If you have a big pond wall or an earth construct that needs serious compaction, this is what you use. You also can get a version of this machine that can be towed behind a bulldozer which cuts down costs. The great things about using a roller is that it really speeds up the job execution when used conjunction with an excavator or bulldozer. It compacts while the other machine moves earth!
It has been said that the surgeon has been one of the most important contributors to the medical system in the history of human kind. I believe that when my children grown up, earth surgeons are going to have a similar reputation. If soil erosion is the main issue that we face on our planet then earth surgery will be touted as one of the most successful mechanisms to reverse this trend. But like everything else in permaculture, techniques are only as good as the strategy and pattern that they are applied with. Without them, you are just encouraging a system that is broken at its core.
Swale distributing water through the landscape after a rain event at Zaytuna Farm