Written by Doug Crouch
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.
Small Scale Terracing
On a southwestern facing slope at my parents house in the suburbs of my hometown Cincinnati, Ohio, USA, I implemented a small zone 1 terrace garden with the help of my father in 2013. We did a simple measurement of contour just below an already existing garden bed that was up against the house which afforded a great microclimate. Thus we were building off of that but wanted to expand the garden so that more crops could be planted and done in an aesthetically pleasing way. Once we had the layout approximated through pegging roughing dimensions based of of the contour measurements, we went to the big box store of Home Depot to buy the stones that we would use. Having not learned the skill of dry-stacked masonry growing up, I felt more comfortable with going with pre-made bricks to do this project. Furthermore, these stones meet the aesthetic of the neighborhood, which is also an important aspect of edible landscaping.
I then cleared the whole area with a mattock to remove the grass that was in the area. It was a slight slope leading to a much steeper sloper at the bottom. I then re-pegged the area with flags making the more precise bed location and began to do the construction. With terracing its best to work bottom up and have some flexibility within the implementation as surprises always occur. The first thing I did was to create a level platform for the bricks to sit on. This is not easy, the most difficult part actually, which is compounded by the rectilinear pre-made brick aspect. I used a large level to help and used a bit of masonry sand to help wiggle the bricks flat on the ground. I have to admit this first wall is a bit shoddy as it was my first time doing it. However, I learned as I went and created the wall by easily stacking these fabricated bricks. After that I then began digging with measurements of how big I wanted the terrace to be. I displaced dirt from the uphill slope down into the container like space of the terrace wall to create a level surface of 1.5 meters. This accounted for the bed space of 1 m, the path of 30 cm, and 20 cm for the next row of blocks to be laid for the next uphill wall. In the pathway area I created a small depression like swale and filled that with wood chips as I had seen it on a much bigger project that I describe below in contour bench terracing section. This gives the water a place to sit when heavy rains occur and is an access path for the beds. Moreover, I simply repeated the pattern as I went uphill creating two more walls. The two bottom ones had more stones as it was much steeper and the top one not as many because of the more gentle grade around the house. I left a walking path of grass in between the existing garden bed against the house and the terraces below. The upper terrace bed has a weird oblong shape because of this and the contour of the terraces so the part that was bigger got a couple of stepping stones to increase access and not diminish the growing space. To finish the process I sheet mulched to build organic matter and suppress weeds and poured a compost extract over the beds to help repair the soil damage. It is an extremely heavy fill clay soil that I have been augmenting over the years with compost but also sand from my families land in kentucky. Since I was driving back and forth between the two for work, I would load several buckets into the back of my pickup from a sand deposit on the family land. I would then pour that into the terraces and hand till in it. This helped to give the soil a different composition (clay loam instead of just clay) helping with drainage, fertility, and overall soil building.
With this project under my belt and working at an organic nursery where I found a client, I was hired to implement a similar project in another suburban location. He liked the look of the one described above and hired me to implement three beds on his land as well. We had the bricks delivered which saved time, compost delivered, and quoted the project for two days. While it should have been quoted for three, myself and one other person worked two very intense days in extreme summer heat. We built off of the experience I had acquired in the last project and worked from the bottom up, did the earthmoving and construction, integrated the compost and also did a sheet mulch with compost extract to build soil before planting was to commence.
Furthermore, individual tree planting platforms can also be implemented on the small scale and are often used for the anchor species of food forests along with their guilds. I have used earth banking below to support as well as contour brush piles made of cane grass as well as stone. Either way the land is leveled and the tree is more easily mulched and watered as neither of these two energetic pulsations are as quick to leave. Neither is the soil that is built there and I am always amazed to see it grow over time with a nice layer of humus at the top and the darker colors that come forth in the soil below as it gets sequestered into the top layers of the soil horizon.
Contour Bench Terraces- Broad acre application
Not all terracing utilizes stone to hold the earth back. Sometimes its just properly banked earth that gives the hillsides stability but also these level playing fields so to speak. I have worked at several of the locations and they are a more modern terrace version that uses machinery more often than not especially on the broad acre. One such location was at a ecovillage in Motueka, New Zealand on the south island where I planted trees and later did some design work. The hillside was given access through a road and then terraces were created off of that to do regeneration work and food production. In this broad acre landscape the main land use was tree crops and berry bushes. The engineer on the project was a great pioneer there and I had the pleasure of working with him on a very similar landscape in Nelson, New Zealand so I got to see the engineering side of design. In New Zealand if you move more than 2 m difference in earth you have to get it approved and an engineer must help with the design. I applaud this rule as there have been failures due to lack of sufficient due diligence with this technique. It does make it more costly, of course, but it does make it safer as the soils were heavy clay and do have the potential for landslides if done improperly. Thus this land was terraced with a machine to gain access and set the stage for land regeneration and organic food production. The machine followed set out contour lines as it wrapped around the hillside slowly scraping the very little top soil off into an earthen downhill berm where tree crops were planted. On the bottom parts of the slopes that had been altered, berry bushes we planted so they could expand easily and access was available. Windbreaks were added to help with the mediterranean like conditions there and also to further staple the hillside together. Tree crops were interplanted with nitrogen fixers and soil remediation using biochar was applied at this particular place.
Another example, which I was not present for or involved in the design, was Terra Mae, which was a piece of land owned by my colleagues in Portugal. The land featured a 64,000 Liter water tank and below that was an abandoned vineyard that had been dying out and enveloped by invasive blackberry and other brambles. Thus they cleared this vegetation and pegged it all out and brought in machinery to do the terracing. The land had become desertified with the abuse of the soil from plough agriculture on this hillside. However it was altered so water would be infiltrated, soil would be built, access was given, trees were planted, and vegetable keyholes beds were created and planted. Although the property has left our collectives hands it is still a short walking distance from where we work at a place called Terra Alta. It too has been terraced from the past and the present. Because Terra Mae is on my walk to town, I keep observing and although intensive food production has gone to the bottom terrace in a corridor style planting of the drylands, its tree crops remain as well as the perennial guilds. Both thrive in the summer dry and despite the lands relative neglect, the trees continue to grow well especially the drought hardy almond and plum. The Asian Persimmon could probably use some more mulch, supplemental watering and the like, which shows how terracing alone is not generally enough for landscape rehabilitation. Thankfully in its original year or so of management, this site was heavily mulched and lots of compost extract was applied to help heal the land. On an energetic level letting the land know more what was about to happen would have helped the end result and I recommend it to all when bringing this sort of machinery and drastic change into the landscape. Simply talking with the land to let it know will help keep the peace at the site on a vibrational level.
For every action there is an equal and opposite reaction- Design considerations
It is important to know that when terracing land the hillside does become unstable until its structure reforms. It took millennia to create this land form and in just a couple of weeks of bulldozing mountain landscapes can be drastically altered. This is fantastic but must be met with the due diligence of tree planting, soil biology repair, and biodiversity aims. Hillsides can be pinned back together with deep tap rooting plants, often nitrogen fixing pioneer trees, like Black Locust. It is used already in mine reclamation work and if it is right for your climate, use it. If not, then try others. This means in your budgeting process you should leave room for purchasing trees and all the cascading costs of that. Labour, irrigation, fencing, compost, mulch, guild plants, are all possible associated costs. Thus it is important to recognize that when you make such a move on the landscape, you should have that as just one of your phases of implementation followed by years of work to make sure the hillside stabilizes and regeneration ensues. Spreading microbes afterwards is vastly important as well with the digging action for sure dramatically setting back soil succession. In other words, and I have seen different figures on this topic, but for every hour of earthworks from a machine, you are looking at 20-50 hours of labour to help do the regeneration work necessary. That is how much stored energy there is in fossil fuels and the equipment that helps to shape it. Consider this strongly before ever taking on such a project with machinery. However if you can pull it off, terracing is a wonderful technique of altering the land in a multifunctional style.
Below is one last graphic that shows the process of terrace building. Pegging it out and having all the materials, tools and labour is crucial just like any project management operation. One last note on the layout is that the steeper the land, the closer the terraces become. Meaning as you move through a hillside, the parts with less inclination will afford broader terraces. As the landform steepens, the terraces become smaller and smaller even to the point of very little access and growing space. However for some this was the only chance. Having spent so much time in Europe I have become accustomed to the terraced landscape and still remain mystified at the scale of some of it. I have also seen a great many terrace walls eroding or becoming overgrown with jungly forest due to lack of mainentance. The energy that our ancestors put into these terraces is worth maintaining, repairing, and doing earthworks within earthworks to keep progressing the land forward. I have been amazed at the rate of regeneration at Terra Alta, coastal Portugal, where I have contributed for a few years (2012-2016). We have terraced the land for gardens, for individaul trees and their guild, and also in combination with sunken beds dotted around our food forest. Its amazing to look back in space and time to see the difference! Terrace, plan carefully, execute precisely, and manage holistically.
Written by Doug Crouch
Header Art Bonita Edwards