Saturday, April 6, 2013

Rocky Resources

Very useful article for the Norwegian topography, from PRI!

Land, Terraces — by Jonathan Davis April 4, 2013


Every geographic area has a resource waiting to be used. I want to talk about areas that have stone easily accessible. Rocks can seem to be a huge obstacle to design and productivity, but there are some valuable advantages that come with having usable stone. Some advantages to using stone in a design can be: freeing the soil of obstacles to plant growth, being able to use that removed stone for retaining walls or other structures, using land far beyond what common ideology says it is worth, using otherwise unused material and simple beauty. Rocky landscapes can be very advantageous to a permaculture designer.

In many soils there are non-soil components, many times being large stones. Anything over 2mm in diameter is not soil. The stones that are in the soil can inhibit, at least to some degree, the growth of plant life and the ease of planting. Good examples of removing the stones from the soil for use can be seen in many fields in Britain. There is a large amount of work that is involved in removing these stones but in many cases removing at least some of them is worth the effort. Increased usability is the goal.

Removing stones from soil is just one side of the coin. The other side is the usefulness of those stones for building structures. I’m talking about retaining walls in particular. With a retaining wall, land can be leveled off, terraced, making it usable in the sense that it is easier to manage, so steep slopes do not have to be navigated. Terraced ground slows rain water, which helps it sink into the ground and combats erosion. A lot of areas are considered to be unusable because of slope, but terraced land becomes usable. Aeration can be increased by having a stone wall, as it lets air penetrate from the side, and not just from above. A stone wall also allows excess water to drain out. Stone walls also create unique microclimates, by absorbing heat from the sun and re-radiating it out to plants at night — allowing plants to grow that are not as cold hardy. A microclimate can also be created by using the walled terrace to block cold wind. It is the removal and use of the stone as a whole project that may make it worth doing, otherwise the juice may not be worth the squeeze.

According to the common ideology of food production, rocky, hilly land has little or no value. Permaculture finds the value others cannot see. For example, if a rocky, hilly piece of property is near a densely populated area and there is no farmland nearby, then people normally bring their food in, at great cost of energy, from further away. But, land that would normally be overlooked can give a permaculture farmer an advantage — as it is cheaper to buy, and can provide such locations with a closer source of produce. Common thought among ecologists is that most farmland has already been cultivated, and much of that has been eroded. With permaculture, the use of different kinds of land is possible, as soil-building can make almost any land entirely usable.

How to build a stone wall is important knowledge to have. Taking stones out of the soil on sloped land can be advantageous, because the stone can basically be rolled downhill. The easiest rock wall to build, and probably longest lasting, would be a dry stone wall. With a dry stone wall, the stones need to be large enough so the wall has the thickness to support itself and any weight on top of it. The wall should also be able to hold back the expanding and contracting soil behind it and even have a slight angle leaning in to the soil so that it does not get pushed over. Dry fit walls can expand and contract as needed, due to changing temperature and water content in the soil, and so plants can grow freely, without the wall cracking, as a typical masonry wall would. Backfilling a wall can be a task, but it does not have to be soil — other good fill can be added when available. Hugelkultur can be used in the design by adding wood to the terrace to add long lasting nutrients, organic matter, water-holding capacity and heat.

There is something inherently beautiful about a terrace; something that says "useful, bold and timeless". A retaining wall with a terrace on top speaks of human ingenuity, diligence and permanence. There is nothing boring or mundane about a feature like a terrace in the landscape.

Permaculture design has many uses for rocky ground, and stone walls are one of those uses with many advantages such as: helping plant growth, usability of removed stone, revealing the true value of land, having a place for otherwise unused material like logs and to just enjoy simple beauty. There are many opportunities with rocky resources waiting to be acted upon. There can be hard work involved in developing a rocky landscape but worth it in the long run.

Let us know your stony stories via comments below!

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