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Terraces Article From Earthworks Chapter of TreeYo EDU PDC handbook

Douglas Crouch
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In depth article from TreeYo EDU PDC handbook on the varying contexts and scales of land terracing. From a look to the past to modern day application this article hopefully inspires people to go and do this piece of regenerative land management. I have had great fun building those and enjoying the landscape here in the north of Portugal now full of them! Terrace, plan carefully, execute precisely, and manage holistically. Header art Bonita Edwards.

Terraces, a long standing tradition throughout many cultures, can still be seen from the past and are being implemented once more for their multi-function approach to landscape productivity and regeneration. They create access, help to slow water, retain and help build soil, and give productive space for production of crops of all sorts including animal integration. They follow the curves of nature and are quite aesthetically beautiful when done with craftsmanship. They can be accomplished in several different fashions and scales which we will cover in this article. These contour retention platforms are a wonderful application of the past and present need for farming on slopes while keeping them productive and abundant.

One of the best examples I have seen in broad acre terracing in person was on the island of Ibiza where I taught a PDC in September 2015. Although mainly known for the party scene, Ibiza was once an agriculturally productive ecosystem aided by terracing the land. It has a wonderful climate because of its southern island presence in the Mediterranean but it is a quite brittle drylands area. Terracing began thousands of years ago and some of the trees planted originally back then, like olives, still can be seen today. These terraces did all of the above listed functions and helped to make the island more resilient in its harsh climate. However some lands changes happened over the years, which are typical patterns globally once the industrial revolution of farming took over. People stopped having a biodiverse set of crops including the shepherding of animals, they began to plow the terraces with metal and more often, and they began to be obsessed with keeping the land clean for fire by constantly tilling. So even with these earth-shaping techniques, it was not enough to keep the landscape resilient enough to sink water into the earth and keep the landscape green and water tables high. Its a holistic and systematic approach that is needed to reverse this and terracing the land can be one of those techniques, especially on our steeper slopes. Swales are done on more gentle slopes so keep that in mind with the graphics and images below to help you decide which feature to implement.

The General Pattern

The pattern of following contour is utilized in terracing just like swales however it is implemented slightly different as terracing creates a whole new contour. Terracing gives a stair-stepped approach to moving the earth and flattening it as much as possible within each terrace or even angling it slightly back towards the slope. While not always completley flat, (sometimes used to create only less steep land) that is the aim so that water has to migrate through the land as slow as possible. Normally in landscapes with drastic steepness waters descent is quick and often erosive, which is exactly what terracing addresses. It also aids in access as most often in farming of such steep landscapes animals were inserted to create a yield but then were mismanaged over the years. Once terraces are implemented, landscapes can have a mosaic of different land uses including animals but also savanah like density of tree crops and those around the house more intensely farmed in a food forest type of style. Row crops were grown more easily as well, from vines to tomatoes, but also a less erosive way to produce grain crops. Furthermore, where terraces bridge valleys, these areas often have the deepest soils and the most humid so special tree crops were planted like citrus in Ibiza. Terraces also aided in cleaning up fields as rocks were moved from fields after ploughing to the walls and then craftily built. Otherwise piles of rocks here and there would be left which wasn’t as aesthetically pleasing. Terrace walls also heat soils from the radiant heat of their rocks so keeping them weeded is necessary for this important growing season extension. It was at one time about human ingenuity, intuition, and a lot of hard handwork. These days we can alter the landscape with machines and precise leveling devices so it is done at a much quicker pace and requires due diligence both in planning and post site recuperation. While an amazing use of technology, the speed of doing it by hand and with animals like in the past also affords a more gentle impact on the landscape. Thus we must be prudent with our planning that a machine driven implementation on the land will require a lot of rehabilitation work afterwards so you may want to start with small ones. Finally if going big, never forget to utilize the approval of an engineer.
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