Infiltration Earthworks

Pattern Understanding

On a pattern level, we must understand that to complete the hydrological cycle we often

Sheet mulching a regenerative Earthwork at Terra Alta, Sintra Portugal 2010

Sheet mulching a regenerative Earthwork at Terra Alta, Sintra Portugal 2010

need to alter our landscape to increase its receptivity.  As land has been degraded from the extractive capitalistic model and poor land management, its ability to receive water and transform this potential energy into higher life forms has been degenerated. Furthermore, we failed to keep traditional systems of rainwater harvesting going because of piping and canals and other technologies as the industrial revolution raged on.  With this broken knowledge set, we must come back to this ancient practice and leverage our current technologies.

With that, the pattern level thinking that is needed in this chapter of the book is to recognize the overall path forward to sinking water.  Waters infiltration depends on the following factors:

  • vegetation type
  • land use
  • soil structure and organic matter percentage
  • Slope
  • complete watershed usage and management

Vegetation Type

Depending on what level of succession the land is at it will be more or less receptive for infiltration.  Forested areas, well developed grasslands, prairie or savannah all infiltrate

Multilayered Forest type but also a compacted road, two different absorption surfaces

Multilayered Forest type but also a compacted road, two different absorption surfaces

water at a higher percentage than industrial agriculture fields, compacted, chemical lawns.  Receptive landscapes leverage development of good soil structure and their use of biodiviersity to create balance.  Forests slow water entry and exit in the system because of its canopy.  In areas that are too dry to support forests, well developed grasslands are essentially like a forest. They prevent soil being bare where water runs off causing erosion gullies and evaporates quickly causing salting.  Both lead to desertification and the catastrophic social and environmental consequences.

Land Use

Use of compost tea vs use of synthetic fertilizers or pesticides will have a dramatic affect on infiltration rates.  Overploughing the soil vs using biological resources to build natural

Runoff percentage from different land use

Runoff percentage from different land use

capitol on the farm also has a cascading affect.  Fungi are integral parts of the fabric of soil building and are ripped to shreds with tilling.  Also is the land being used for a road or a well mulched organic garden.  The road will be an impervious surface and through creating beds on contour or terracing and building organic matter rich soil, the garden will be very efficient in infiltration.

Soil Structure and Organic Matter Percentage

Essentially all of the these headers point to this one as it is the fulcrum within the water

jar test for soil type

jar test for soil type

infiltration system.  Clay soils inherently have lower infiltration rates as opposed to well balanced loams or sandy soils.  All of those soils are balanced in terms of water infiltration and water holding capacity by raising the organic matter percentage.  This helps to create better soil structure which facilitates the infiltration of water, more developed root systems and greater photosynthesis which shows the exponential factor of nature.  Moreover, on overgrazed, degraded pastures soil organic matter has been washed away and the exponential degradation speeds away like the runaway freight train.  However, when we combine efforts of stimulating the soil food web, planting for biodiversity, regenerative earthworks, creative human interaction and rotational grazing, completion of the hydrological cycle is catapulted.

Slope

Flat lands tend to have higher infiltration rates because of the embedded energy in flowing water.  This is why earthworks to create level land through terracing or speed bumps along the way known as swales are so important in our regenerative earthwork approach to increasing water infiltration.  So as slopes increase more water runs off and reforestation on these steeper lands is really important.  Giving these lands up to fodder producing tree crops is a much better land use than grazing which tends to really erode these soils. On the broadacre on our land where the slope is not to steep to bring a tractor in, keyline can utilize its pattern of bringing water from the valley to the ridge thus rehydrating landscapes and facilitating reforestation efforts.

Steep Slopes of a reforestation project at an Ecovillage in New Zealand

Steep Slopes of a reforestation project at an Ecovillage in New Zealand

Complete Watershed Use

Unfortunately in our cartesian approach to development over the last few hundred years,

Boundary lines of a very unique 130 HA project that is complete watershed in Alentejo, Portugal

Boundary lines of a very unique 130 HA project that is complete watershed in Alentejo, Portugal

we have divided land in squares quite often and ignored watershed lines.  You may have really great soils and nice earthworks, but your position in the watershed might leave you at a disadvantage for water infiltration.  I know this is true from my time in the Dominican Republic and the low lying property I worked where the neighboring lands poor land management caused many our our water headaches. On that above piece a keypoint dam with swales extending would have solved much of our problems.  So consider this in your assessment of land.

 

Earthwork Design Process

From there we can decide how to improve our land use and intervene with earthworks when needed.  Sometime its not possible and simple contour brush piles are the key.  Sometimes we are talking about rehabing the braod acre while other times it is the urban or suburban context.  So first is examine your context in the framework of the above points and the other social, legal and financial constraints before taking on an earthworks project.

Earthworks can be incoorporated once you have done the due diligence in the design process to consider all of the complexities of it.  On a project that I consulted for in extremely dry and degraded lands of Andulucia, Spain in 2010, the client had already contracted out one of the worlds leading Permaculture Designers to do a design.  He designed in several kilometers of swales and numerous ponds on this broad acre project.  However, dam building projects in this region have huge legal constraints and the client was not so happy with the aesthetics of swales especially on the extent that was called for.  A quick analysis of the land for myself revealed that a combination of keyline and compost tea without the keypoint dams would be a much more logical solution and a fraction of the cost.  So below is a graphic of design considerations that comes from Bill Mollison adapted by myself from his Introduction to Permaculture book.

Design Graphic Bill MollisonTo create the design, the harmonious integration of landscape and people, many factors are overlaid and we shy away from the rubber stamping of non-contextual dependent development that already plagues the earth and social systems alike in the pursuit of unfettered capitalism.  If you look at something like Keyline in the above context, we can easily aim to create an overlapping circles of all considered factors.  In this sense we are channeling the flower of life pattern and abundance is sure to follow. Lets look at Keyline design in the four factors above to set the context better.

the keyline pattern

the keyline pattern

Social

With that, Keyline considerations include in the social aspect the legal constraints of dams yet give us a window of opportunity in the ploughing as it is minimal earthworks and no planning commision can turn this down. Farmers are ploughing all the time so

keyline Darren Doherty talking to tractor driver

keyline Darren Doherty talking to tractor driver

this provides no hinderance as their a cultural tendency to manage land in this way could never be a social implication. So local farmers may indeed be more receptive to implementing what they see in a project such as this as your are not asking them to hand dig something that they really don’t understand.  It is a different plough type, a subsoiler, and a different plough pattern, bring water from the valley to ridge, and that is where education lies within the social context.  Also we must look at does the client have the finances to do such a project and who is the person who can lead this design and implementation work.

Site

The gentle slopes of a worn out hay field in Tennessee where we plowed in 2009.

The gentle slopes of a worn out hay field in Tennessee where we plowed in 2009.

In this context the above factors were already laid out for the most part.  Does the land have slopes that tractors can reach, does it have soils which would be receptive to dam building, does the current vegetation type permit the ploughing, and what climate are we implementing these projects in? This last factor ties into the timing part which is one of the abstract factors and shows how thinking holistically rather than cartesianally with its mechanistic worldview will create the balance and subsequent abundance that we seek. Also we must ask does the site have potential spots for keypoint dams and how can these integrate into the overall farm design and management plan.

Energy

One of the key factors to keyline is the technology itself.  Do we have access to this modified sub soil plough?  If we don’t, how can we implement such a project? This ties

keyline plow closeup

keyline plow closeup

back to the first factor of who can do it and what is the price?  If we are to do it ourselves, how long will it take to acquire a plough and what is the cost of such a thing?  The purchase of tractor implement is a common agriculture endeavor and grants maybe available reducing our energy input of finances.  From there we must examine costs of the fuel to power a tractor and if dam building is involved in the keypoint dam aspect of this regenerative broad acre technique, then is the equipment and know how to construct present in your context?  When Yeoman’s was building massive dams, diesel was five cents a gallon which is a far different price than what we face globally.  This tends to make us build smaller dams yet the machines for earthmoving have become more efficient as the technology has progressed.

Abstract

The timing around when we plough is very context dependent and one of the key factors in your phases of implementation part of the design process.  It is just before flushes of Ethics imagegrowth which depends in the tropics on your rainy/dry season just as it does in the Mediterranean.  Warmer soil temps in the temperate and Mediterranean regions in spring are also signals of growth while tropical systems cooling down because of the onset of rains might also signal growth.  Furthermore, we must collect sufficient data to make these projects successful.  Surveying the land is essentialt in the field and our initial planning is greatly aided by topographic maps which are more or less available to us depending on where you are at in the world.  Ultimately this hinges upon our ethical approach to development.  If you feel keyline is a great technique, then implement it.  I have received questions about this technique over time of if it could be done without the use of fossil fuels but rather with horses. Technically the answer is no as horses can great aid in swale building which is an overall similar technique but keyline itself does use fossil fuels.  So check in with yourself on all of these overlapping design considerations for all of your earthworks projects.

Earthwork Pattern

sien art- patterns

To facilitate waters infiltration, growing space proliferation, soil stabilization to accrue organic matter percentage, and overall acceleration of succession and evolution, earthworks are designed and implemented to reduce spirals of erosion.  They create landing spots for water, slowing its descent and storing it in the ground and the subsequent vegetation that is quite resposive to this action.  It is also stored in humus, or organic material that has broken down into a stable carbon compound.  Increasing your organic matter percentage has an exponential factor on the soils water holding capacity and is a lasting factor in insuring that photosynthesis rages on when non conducive patterns of growth occur such as prolonged dry or wet periods.  Humans initiate these earthworks and are an essentail feature in evolution and maintenance throughout time.

land surveying with a laser level at the carbon farming course

land surveying with a laser level at the carbon farming course

Whether it’s the terraces of Asia or Europe from antiquity, or the keyline pattern of development from Australia in modern times, these systems have the age to tell us of their successes.  Through their implementation, continual maintenance, and succession, we are able to accrue natural capitol which leads to balanced systems.  This natural capital cascades to financial capitol in higher farm profits while sculpting the earth usually has a profound impact on property values.  These successes of bumper crops easily leads to the fair share ethic through sharing surplus which includes job creation which stimulates a local economy and the people care ethic as people find increased opportunities for right livelihood. On a physical manifestation level, surveying the land with our eyes and then technologies, crude and refined, such as laser levels or bunyip or water levels, allows us to read the landscape so we can implement these elements.

Earthworks Techniques

Once the land has been surveyed and all the aspects of the design have been considered, there are choices to be made on which elements to implement.  Our zone planning in Permaculture allows us to define these choices but there is no set formula.  However I consider certain factors more broad acre or to be done on the small scale.  Most can be adapted to either or so don’t let your preconceived notions be limitations and remember Bill Mollison’s attitudinal principle of “the yield is theoretically unlimited, it is only our imagination and information that does so” guide you. With that the following are your most common earthworks within permaculture:

  • Swales (on contour ditches and mounds with associated plantings)
  • Diversion drains (off contour ditches and mounds, often called canals)
  • Rain Gardens ( depressions in the ground where runoff is directed, on a bigger scale called infiltration pits, these berms and basins are accompanied with plantings)
  • Terracing (leveling earth to create a stair stepped effect on the landscape)
  • Keyline (ploughing with a modified sub soil ripper creating mini swales, plough pattern brings water from valleys to ridges, and is often accompanied by keypoint dams but not always so, also involves some level of reforestation)
  • dams (compacted earth to store water with minimal to no infiltration occurring, the water is then spread in the landscape using other techniques including evaporation)

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As said before other techniques on the land that help to increase water infiltration and often accompany earthworks are the following:

  • Stimulation of the soil food web (through extracts and teas, cover cropping, chop and drop, diverse plantings, and so so)
  • Biodiverse plantings (these systems stack in space and time and one representation is the food forest strategy, they mimic natural forest and place an emphasis on multifunctional species and serve many functions such as firewood, windbreaks and fodder)
  • Rotational Grazing (animals are moved in a pattern that mimics the natural herding tendency of herbivores when pressures of predation are present, this is dramatically different than conventional chemically driven systems that are the main form of animal husbandry and extractive industrial meat production
  • creative human interaction ( our systems require humans to initiate and reevaluate the design and implementation and then alter succession so that earthworks are long lasting and soils are built which increases waters infiltration.)

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2 Responses to Infiltration Earthworks

  1. Pingback: Infiltration Earthworks | A Permaculture Design Course Handbook | TreeYo Permaculture

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