Week 2: It’s all about the water-Earthworks August 2nd-August 6th

This is the first course that is open to the public.  A couple of other non-interns participated in our study and action of planning for and moving earth.  Swales, dams, culverts-all are needed to control the flow of water-the blood of life-over the land if we wish to slow the flow of water.

Throughout recent agricultural/urban history water was thing to get rid of, to move away quickly.  As long as energy is cheap, water seemed more of a nuisance than a need.  Dig straight channels, drainage ditches, high dikes-get the water away.  Large mechanical machines have moved enormous quantities of earth-often causing long-term negative consequences with water availability on the land. Yet now, to repair the damage, we must also use large equipment-perform “geosurgery” as Geoff Lawton-Permaculture Research Institute of Australia, calls it. 

We had some discussion regarding using these large machines.  Using fossil fuel, heavy equipment to dig up the earth.  We discussed looking at the long-term productivity that these systems will have.  An estimated 800-1000 people would be needed to move as much earth as fast as the excavator.  In situations where manpower is more available, this may be feasible. 

For much of our earthworks week we worked in front of or behind a 25 ton pivoting arm excavator.  In this photo, the excavator is making the swale.  A swale is part of a tree planting system that represents a long-term modification to water flow over the land.  The swale enhances subsurface water flow, slowing down water, giving it time to percolate into the soil and subsoil.  The swale bottom is nearly exactly level-we measured the level using a couple of methods.   The dumpy level (transit-see photo)

One main premise in permaculture based water management is to hold or slow down water flow as high in the land as possible.  How this is done depend on the topography and the geology of the site.  If you are in a wilderness survival  situation one of the best places to carry water is in your stomach.  Likewise, the best place to store water for plants is in the soil.  Using a combination of dams, and swales, it is possible to capture as much rainwater as possible and get it to the plants as they need it.  By carefully placing swales and dams into the landscape, the need for irrigation or watering is reduced or eliminated.

All of us became very impressed by the skill of the excavator driver. 

As soon as the swale or dam was finished by the excavator, we planted a cover crop to help stabilize edges of the banks.  This cover crop was a mix of plants such as vetch and field peas.  Later shrubs, trees and other plants will be planted to transform the land into a food forest.