Terracing

What is terracing?

Terracing cuts a hillside into steps. Each step is level, or nearly so, and each is held in place by something: a retaining wall of stacked stone, or a bank of earth held by its own vegetation. Italian keeps the two apart, calling the walled version terrazzamento and the banked one ciglionamento, a distinction that English and German tend to lose.

The reason is water, before it is anything else. Rain falling on a long uninterrupted slope gathers speed, and moving water carries soil. Break that slope into steps and the water is stopped again and again, each time with a moment to soak in rather than run on. What was loss becomes storage. On a Mediterranean hillside, where the year's rain arrives in a few heavy weeks, that difference decides whether the summer is survivable.

The second reason is simply that a level surface can be worked. Terraces made steep ground cultivable across the whole Mediterranean, and the landscapes we now consider beautiful are largely the result: olive slopes, vineyards, orchards on ground that would otherwise grow nothing but scrub.

The uncomfortable part is what happens when the work stops. A terrace is not a natural form, it is a structure under maintenance, and abandonment does not return it gently to nature. Studies in south-eastern Spain measured gully erosion on abandoned terraced fields at roughly 87 tonnes per hectare per year. The mechanism is unkind: without cultivation the surface seals into a crust, infiltration drops, runoff rises, and the wall that held everything gives way. Research on Mediterranean olive terraces found soil loss increasing with the length of abandonment, and the effect becoming much stronger on slopes above about a quarter gradient.

So an abandoned terrace can lose soil faster than a slope that was never terraced at all. This is one of the places where leaving land alone is not the same as healing it.

How Terra Humana understands it

Terracing is not a technique Terra Humana chose. It is the ground we found.

The official landscape survey of the Ogliastra is unusually direct on this point. It names terracing, subsurface drainage and retaining walls as the interventions without which the steep slopes of the district cannot be worked at all, and it records that viticulture was economically significant here, naming above all the municipalities of Jerzu, Gairo and Tortolì. Sa Medada lies in Jerzu.

The regional government treats terraced landscapes as elements of particular rarity in its own methodology for rural landscapes. So the terraces are not just useful, they are recognised as heritage in their own right, in the same way the dry stone walls that hold them are.

For us the erosion figures are the argument that settles a question of method. Withdrawing from a terraced hillside is not a neutral act. Somebody built those steps, and the choice is between keeping them or watching the slope take back the soil faster than it ever would have. That is why our work here is active cultivation rather than release.