Earthworks- Sculpting for Fertility and Access

Terra Alta and the surrounding lands have had human interaction occurring for countless

terra alta source

terra alta source- Moorish and 1000 years old or Portuguese and 50 years old?????????

centuries.  This influenced not only the vegetation, wildlife, and soil fertility, but also the terrain itself.  Some of the land and surrounding hillsides were terraced some years in the past and planted with tree crops which help to form our food forest.  One of the unique things about Portugal is it is hard to tell if it was done in the 1950’s by Portuguese farmers or a millennium ago by the Moors.  The latter were experts in drylands agriculture and helped to reshape Iberia through their ability to tap into water sources, move water around landscapes, and sculpt the earth for fertility and access.  Thus we have continued this work and our future phases of implementation will continue to deepen this work as well as making sure water has a space to infiltrate.

The Access Road and Water Channel

One of the first major earthworks that occurred at Terra Alta was rebuilding the access.  This is a costly process and must be done right for it to be a lasting feature.  If not it will be a financial drain so take the extra time upfront to ensure it is well designed and implemented appropriately.  It is a layering process with different aggregates and must be done so that water is constantly moving off the road and into the adjacent water channel.  We have two channels that enter the land that are recipients of staggering volumes of water from the roads above the land (nearly a Km worth of impervious surface).  This flow falls into channels on either side of the road and have been altered so that these huge volumes of water are not just flowing into the main stream but rather first circulating through the land.  By creating lots of edge we are working positively towards a full hydrological cycle.

The Rain Garden Serpent- a mandala of infiltration and growing

The next big earthwork was the rain garden serpent.  Being a pattern in nature and classic symbology of many ancient cultures, the serpent shape was formed with heavy machinery to install a new version of how we cultivate our water resources.  Having an

400 Meter Serpent Mound Earthwork in Central Ohio

400 Meter Serpent Mound Earthwork in Central Ohio, USA

incredible amount of water flowing on-site from the impervious surface of the roads above the land, this shape facilitates infiltration, flow, and regeneration.  It is a series of channels that interlinks ponds, which are more like rain gardens as the water is not held all year round.  The sandy soils do not hold water well and despite the addition of clay it is not enough to create an appropriate seal.  One day we do hope to find the appropriate technology to make it hold.


Top settling ponds with the largest pond below and channel connecting

There are different sized ponds all stair-stepping down the land and following a sinuous shape.  This creates a wonderful ambiance as there are even small drops with waterfalls when the heavy winter rains persist.  The largest of the ponds at the top of the system is a huge infiltrator and helps with water quality throughout the whole of the system.  The water circulates the curves in three dimensions and is wonderful expression of edge.  The adjacent beds are used for food production and the channels are used for access when the rains aren’t present.  We fill those channels with organic matter as well to break down slowly and scoop it out into relative location onto the raised beds.  Slowly we are building soil fertility and the yields are flowing from setting up this long-term system.

terra alta serpent earthwork

Aerial with channels and pond earthworks serpent mandala

The Stream Pond

In the middle of the property, a seasonal stream flows that can be quite torrential at times.

Our mountain of Sintra stream

Our mountain of Sintra stream

It is a steep drop in this area as the water bubbles with these flowing forces and the stream folds the land in two creating different aspects towards the sun.  Water is the ultimate sculptor and its sensuous curves are profoundly beautiful.  To slow this torrent down and do some energy cycling, a pond was built.  It’s a simple design of an oval shape about three meters long and two meters deep but retains lots of the slower flow and allows it to sink into the ground.  During the heavier flows it gives the water a chance to spiral a bit and cleanse itself during its rapid descent and then flow downward in the valley below after its trip through the spillway.  We grow floating aquatic plants on the surface to pick up the nutrients that are flowing downhill with it and can be used as mulch for the plants growing in relative location.  Also on its edges we are beginning to expand our aquaculture with emergent aquatic plants such as New Zealand Flax as it is a great fiber plant.  Just up from that we have tree crops such as the already existing quince and also newly planted Feijoa.  One day the Feijoa will tap its roots directly in this water and the trees will be very happy that we created this edge.

Terra Alta base map from 2012, note middle pond in the stream

Terra Alta base map from 2012, note middle pond in the stream 

Keyholes- Earthworks within Earthworks

The earthworks of the site are not static and have been redefined over the years to make earthworks within earthworks and often within earthworks.  Little mini terraces support plants on the outside rim of the ponds/ inside rim of the growing space.  Keyhole beds have been added to decrease the height of the earthworks as the raised beds were just too high and were facilitating drying out in the summer that was not conducive for growth. These keyholes drastically increased our growing space and the accessibility which helps because the impetus to step on the beds has been alleviated.  Within the keyholes, we even try to create mini sunken beds to facilitate the drylands growth.  Also on our raised beds, the paths are fully mulched to reduce the raised effect and creates sponges of moisture and pockets of breakdown in our dry summer months.  This soil is then lifted and put back in the beds as the fall bed turnover occurs.

Terracing For Individual Trees and their Guilds

In 2012, we did minor earthworks in other parts of the land as well during our food forest workshop. This was mostly in forming a sub-tropical forest garden in a more humid and sheltered part of the valley at Slide077Terra Alta.  This stretch of land below the tank is a nice microclimate and we have chosen to plant greats like Avocado, White Sapote, Feijoa, and Annona.  Because the valley is sloping to the north, we made small terraces around where the trees would be planted along with their subsequent guilds.  The design image from our Educational partner at TreeYo Permaculture shows exactly what this looks as it is hard to communicate subtleties of moved earth in pictures.  But everything is thriving and these earthworks again facilitate water infiltration and soil buildup because of the initial leveling.  They also make access into the tree easier for routine maintenance tasks whilst the tree is young.

Avocado mini terrace

Avocado mini terrace fully mulched and young guild plants emerging

Sunken Beds- A Drylands Technique

In 2013 in our summer PDC, we also shaped the earth in a new way by creating sunken beds.  Despite our abundant water from our source, the task of watering itself is quite labor intensive in our raised bed gardens.  So the books say to dig down in drylands climate and having seen others successes with this technique, we went for it.  So we made sunken beds on this same valley as above to help increase the functionality of the food forest and stack in space and time as the system is quite young still. By digging down and displacing the material downhill where we wanted our pathways, sunken beds were created by a group of hard-working students and direction from Doug Crouch and Karsten Hinrichs. The beds are about the same width as a normal raised bed (1 meter) but our larger one does require keyhole adjustment as well.

sunken bed creation terra alta

sunken bed creation terra alta- the terracing effect

Jerusalem Artichoke Flower

Jerusalem Artichoke Flower

These beds have shaped Terra Alta into a more abundant place as we are focusing on staples and perennial crops since they are more in a zone 2 forest garden situation.  The sunken beds should require less water as the other beds facilitated drying out because of so much exposed edge.  We hope the wind will be swept over the beds and these spaces becomes zones of moisture. From that we hope that Jerusalem Artichokes and Asparagus will flourish as they have been tough to grow in other spots. We look forward to more digging and mounding in the years to come and enjoy this process of sculpting the earth; fine art it is!!!!!!!!

Sunken beds

Sunken beds looking uphill where you can only see the raised pathway but the not the recessed growing space.

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