Permaculture Designers Manual
CHAPTER 9 –
EARTH WORKING AND EARTH RESOURCES IN PERMACULTURE
Section 9.9 –
Earth Resources in Permaculture
Whenever earth is moved, it seldom reveals a uniform composition; in fact, most excavation reveals materials already sorted by nature and of specific use.
To mix them up is to set back the clock a few thousand years and the supervising designer or property owner will do well to follow every excavator (animal or technological) and put aside the following:
Topsoil is the often dark, root-filled living surface of the earth. It is to be carefully stripped off, piled aside and later returned over other material onto banks, over padi or fields and even below water in ponds.
Topsoil can be very thin and rare, and is usually no more than 6-18cm deep. Where deeper, it can be spread on poorer soils to help them produce, or pocketed for trees in poor soil areas.
Excavation in marshes, bogs, or lowlands may reveal 1-9m (3-30 feet) of semi-compacted fibrous plant material. Most can be stockpiled, otherwise 0.6m (2 feet) or so returned to the surface as for topsoil.
The peat stockpile is most valuable for mixing with sands and loams for making even more topsoil. It can also be used as a fine growing medium in nurseries, as an insulator in buildings and only in desperation as a fuel, for those who burn peat are near the base of life on earth; the next step is into barrens and rocks.
Peat lands throughout the world now urgently need preservation as threatened habitats of unique vegetation.
Peat preserves timber, animals and such unexpected treasure-troves as hoards of acorns and firkins of beech butter from the forests which preceded the bogs.
A whole archaeology may very well lie in peat and the pollen record may reveal past history. At the base of Irish bogs the Fir Bolg (the little people), their axes, bridges, butter and forest life are well preserved.
They and their forests were banished, as if by magic, by the Tuatha de Danan (the Children of Diana) who now digs the peat. Diana was displaced in turn by Mary, mother of God. But all are mixed in the peat and the tongue of Ireland.
Good clay is very useful stuff; a depth of it can extend 0.3-6m (1-20 feet). This resource can be stockpiled and preferably covered with plastic sheets.
Both dried and baked brick can be made of it, dams and ponds sealed and pots shaped and fired.
Some types of clay make good cricket pitches and other types make fine porcelain or special filters and insulators. Fireclay Is 58-75% silica, 25-36% alumina, 0.25-2% iron oxide; silica bricks 95% silica, no alumina, and <2% of lime.
Clean, it may make grinding powder or silica chips, or if yellowish have enough calcium to counter acidity. If fine and black, it may be of use in casting metals or as a material for a black-sand solar collector.
If white, it reflects light like snow and can reflect heat to houses and walls.
Fat sand (containing some clay <20%) makes ovens and mortar; sharp sand (or mostly silica) makes glass and cement or can be mixed with peat to grow trees or other plants in nurseries (the best use).
Sieved sand gives special sizes for special use as a grit or polish in mortars and grinders.
Heaped up, it makes good roads, drains and soft sun-bathing patches much better than lawns (no green stains).
Angular, gravel makes good concrete and smooth, good water filters or enzyme columns.
It is mulch for trees, as is cinder and crushed pumice. 19mm-size angular gravels are the best for heat stores, where air from solar attics or glasshouses is blown into a heat store wall or tank filled with such gravels.
Heat stoves can be placed under floors to heat gravel beds.
Shingle is good under gravels on roads, for drains and coarse filters.
It is excellent mulch for condensing water in deserts or dry places, a refuge for snails and decomposers, a filter bed for swimming pools au naturel, and so on.
Floors, tablets and billiard tables are of slate, as are roofs.
Any rock that can be split can be utilized for walls and houses, roof areas, garden paths and floor tiles.
Boulders can be used as coarse mulch, wildlife refuge and walling and windbreak material which gains and radiates heat.
Some boulders are very good as pounders, others excellent mortar and pestles, weights, anchors and ballast in boats.
To me at least, a bulldozer or excavator is a source of information and the making of a pond is a rare chance to explore, explain and store useful information and material relating to the site.
On a complex site (old volcano, shoreline, swamp, or desert pediment), one can confirm or deny theories on formation, geology and geological history.
Best of all, experience on many sites gives a predictive capacity on similar sites and more confidence in finding the right sites for ponds, excavated houses, silos or silage pits and in finding more earth resources.
Just for a careful look at the actual operation. It would not be uncommon for excavation to pay for itself on any one of the factors listed and for yourself or your client to benefit long alter the water storage is built, from materials put carefully aside during excavation.
If you are wise, you are wise, you never leave the site when earth is being moved; it is very expensive to bring machines back for fine touches, to adjust the work, or to sort out mixed materials.
TRACKS AND SIGNS
Like the snow and windblown sand, newly moved earth and puddled clays reveal to the observer a section of earth life and makes an imprint of those secretive and nocturnal birds and mammals on site, from beetles to elephants, mice to plovers.
After rain, it is a good time to take a notebook and observe the footprints, scrapes, and tracks of any site where earth was freshly moved.
A list of species obtained this way adds to basic information resources and may warn of troubles in store from ground foragers. Many cryptic animals avoid traps, but can be detected by their tracks.
The earth hides a great variety of life forms, from secretive larvae and worm-like legless lizards to redolent fungi revealed only on the surface by their garlic-like scent or fruiting bodies.
Mice, gophers and larger mammals leave tunnels, nests and food stores underground and all these and other secrets, such as the extent of root penetration and spread, can be revealed for our analysis.
SHARDS AND FOSSILS
Under the earth, almost everywhere, lie the mute stories of prior life. These have more lessons for us than do futurologists, who after all can only look forward by looking back first (or they would not know which way is forward).
The camps of our ancestors are revealed in soils by shells, tools, shards, ashes, bones (and can be so dated). Buried trees give growth rings to tell the story of older climate, air quality and to accurately date their own burial.
Pottery shards may encode astronomical or technological data and bones reveal past diseases and wars.
As the Ganges River today bears its children’s bodies, their clothes, adornments and possessions to sea, to race blindly over the continental shelf to the ooze below and as we carelessly drop broken pottery on the ground, so in the far future other people (or other minds) may want to know about us, how we lived and perhaps when and why we died.
Today’s disposal pits may well become tomorrow’s mines. They are ourselves in past cycles, an expression of life preserved for our education and guidance.