Aquaculture, Compost, Conservation, Dams, Demonstration Sites, Fungi, Irrigation, Land, Material, Potable Water, Rehabilitation, Soil Biology, Soil Composition, Soil Conservation, Structure, Surveying, Waste Systems & Recycling, Waste Water, Water Harvesting — by Richard Perkins September 15, 2012
A reflection following a great time finding solutions for dryland water management in Portugal
I’m enjoying working on a job connecting up extensive irrigation in the mountains of Extremadura, Spain, and relaxing for a couple of days after a successful and effective Dryland Water Management intensive at the budding Permaculture Institute, Vale De Lama, near Lagos in the South of Portugal.
This week we have been looking at all aspects of water design, focusing mostly on this varied site where all manner of interventions are necessary to halt the onslaught of the desertification process and regenerate the diverse mixed polycultures and rich soils that had a biological diversity comparative to more tropical regions at one time.
Something that is clear after working so intensively with integrative and regenerative systems design around the globe in different climate zones is that most places I turn up at have been degraded heavily and the localized cultural approach and ecological understanding is often limited by familiarization with the current conditions and often destructive agricultural practices.
Reading the landscape it is clear this part of the Algarve was once retaining and cycling moisture and looked very different from the bare soiled and overgrazed carob, olive and almond orchards of today. Green exists here only where water is being poured through the soil continuously and that tends to be either golf courses or citrus production. Looking around I see the rounded landscapes of a much richer past. Soils must have been thick and dark when this used to be a warm temperate haven. Now it can only be described as a brittle landscape, ever shifting towards desertification. And so we study soil. We study all about soil. If you want to turn this landscape around you cannot hope to separate water and soil. Naturally you cannot realistically neglect any aspects of the permaculture pie and expect to optimize the situation, but managing water effectively in drylands begins with soil and quickly leads to trees and all manner of anti- evaporation strategies. By drylands we are typically referring to areas where evapotranspiration exceeds precipitation. It is important to understand that areas of eastern England where I am from have the same rainfall as this place. At 550mm there is not a shortage of water by any means. But the soil is too damaged to slow and store it. There is not enough soil to support vegetation to retain and recycle it. The more the land degrades the quicker and more effectively the erosion features lead all surface flows out to sea.
In any climate I teach in, in any particular circumstance, people tend to come up against particular shared limitations to that particular climatic setting. Naturally. That is partly the benefit and clearly, in my mind, the necessity of working, learning and experiencing different climates to become ever more effective designers. I have little experience with foreign language, and am always impressed with European friends who are fluent in four or five, and I am often told it is the best way to learn about your own language. Well that’s how I relate to interpreting and applying nature’s patterns, seeing opportunity regardless of the conditions and limiting factors of a particular situation. Studying and working in different climates informs our approach and response in any particular setting.
The previous week I was in Sweden teaching, and in a cold temperate zone you can focus in on leveraging everything in terms of heat sinks and microclimates. Here with the limiting factor of water you simply leverage everything possible to slow, sink and store every water source possible. Water is the basis of all life, and you need to get it under control to grow the crops and integrate the animals to build up the carbon that turns this whole desertification process around. That is what good water design is about — getting water under control, slowing its flow by taking it over the longest distance possible over the longest amount of time with the most passive friction and positively effecting more life to create more diversity and abundance.
Soil is the cheapest and most effective place to conserve water, with more layers of stacked benefit than any other way you could store it. One particle of humus can hold on average four parts of water, and so we start to see the cost effective, production-increasing effects of building healthy soils, the basis of all our production, and indeed, of civilization itself. For every percentage increase in soil carbon we increase the soil water holding capacity by 144 000l per Ha. Around the farm, a typical 40 Ha patch around here, we see evidence of pedestaling around multiple trees evidencing between 200 and 300mm topsoil loss, and I would put my dollars on the majority of this happening in the last 80 years, if not 50. If you apply the higher rate evenly across this landscape, realizing 120 000 ton net loss, things start to take a new perspective. We currently lose around 24 billion tons of top soil a year globally, largely to poor agricultural practices, which equals out to about four tons per person per annum. The dry, bare terracotta soil surface typical in this region today is the scarred scabbing of a deeply injured land.
So how to turn things around? Well, it is not so difficult to identify useful potential solutions, and by marrying up these with the budget, resources, priorities, etc, we can begin to select the appropriate solutions. There will be some intensive work, clever planning and constant reassessing to do. And it will not all happen at once. But it can happen, no doubt!
An important area for our designed response involves collecting and collating data and designing ways to reduce water use to eliminate any current ‘bleeds’.
By designing ways to capture, store and slow water, reduce evaporation and human consumption we can turn any situation around. Installing flow monitors and clocking water use we can collect tangible and very useful data to share with others as we transition to more intelligent production systems.
Exploring roof catchments and understanding catchment coefficients from different roof materials, etc, allows us to consider safe and free drinking water possibilities. We discuss ways to harvest rainwater effectively and it is not long before one participant returns with the size of ferro-cement tank necessary to provide 30 people a day with 5l of drinking water each year round. Nice! It’s useful to multiply the number of people with the daily consumption and the longest dry period in days to establish required tank storage.
Ferro cement is one of the cheapest and easiest ways to construct water tanks anywhere with minimal materials. We have also used it to make saunas and shower rooms.
Some basic plastering skills are required, and getting familiar with forgiving earthern plasters is useful….
This week we have been exploring various clear approaches to the essential patterning behind the thinking and actions we will take on this property. We can make minor interventions that cost nothing and are easily actuated, and complex these with more materials, money, etc, to see more beneficial or faster results. We can start with the orange orchards.
Currently there are 200 trees on irrigation, with bare soil below as is typical in these parts. Some critical observation and application of our new soil knowledge leads us to a patterned response that we can scale up in any way we like depending on the resources, money, time, labour, etc.
Lets go through the design approach.
Firstly I look around and analyze the current situation. We have trees on conventional grid patterning, not maximizing footspace in the orchard, and allowing a lot of sun to the unprotected soil surface. This is an opportunity for mixed species and layers of cropping in the future. Right now we need rapid soil restoration to set off a set of beneficial chain reactions in the opposite direction than current degradation. Delicate fungal networks are the first thing to die back in exposed, baked soils. We dig down and find the top 15-20cm is dry and lifeless — virtually no carbon, no water. I suspect this soil had 3% carbon not so long ago, and I want to see it return fast to maximize biology and water holding capacity.
The first concern is the spray irrigation under the trees. Spraying onto these soils is, at a guess, losing 50% of the water to evaporation immediately. My next concern is the spray jets are aimed at the tree trunks and the soil water column is less than a 40cm radius around the trunk. These trees are not feeding and watering here primarily, and with continued watering in this pattern I would expect to find very odd rooting patterns if we were to do an archeological dig on one of these specimens! So, when a bit of research has been conducted, I am not at all surprised to find we are applying 4 times the government recommended irrigation limits. It’s probably well over 50% evaporation. We can change this around at no cost with very little work.
The first thing I would consider is exchanging the spray jets for tree drippers placed out just beyond the drip line of the tree. This dripping on the soil surface will create plumes underground, penetrating far more effectively than surface spraying ever could, and placing it exactly where the tree wants it. We can expect to cut watering down dramatically just from this action alone, as well as promoting healthy rooting which will have various beneficial affects.
Next, if we divide the orchard up into individual areas surrounding each tree, we can make small yet very effective earthworks by hand to ensure all the water that lands as rain, as well as irrigation sources, accumulates in the area extending out from the dripline of each tree. Now we can naturally sink water where we want it, and can treat each tree zone as its own catchment. In this scenario each tree has over 20m2 catchment for itself, which equates to nearly 11.5 cubic metres of rainwater landing and moving exactly where we want it. Currently it is not getting stored in the soil, but we can change that too.
Simple hand dug earthworks can direct rainfall where we want it. We can account for the tree’s current and future size and get water going where its needed. Even simple dry mulch will benefit infiltration and reduce evaporation. We are taking that one step further for this lucky tree!
So we need carbon. Humus rich soils in eastern England are in the same process as this landscape, albeit quite a lot further behind. The deep carbon rich soils can maintain life and a sense of stability for longer, but once the carbon has gone that will change. So here we need to put carbon back. During the course of this week we have studied various ways to do this. From the simple, cheap and successive through to the more rapid, intensive and more costly approaches. We have looked at how to do it mechanically, biologically, with plants or with animals. We’ve talked about integrating all these approaches and strategically beginning in areas of the land where something is already happening. There are so many strategies we could employ here, whatever the budget, needs, goals, etc. It is important to remember when designing that what may be a perfect approach for one client may be perceived differently by another with the same conditions but different aims, budget, etc. It does not matter which particular strategies we employ, as long as we are clear why, and understand the patterns behind our interactions.
So here we are going to mulch. Serious mulch! In this climate I am looking to leverage every possibility, so when I say mulch I mean real thick, nutritious mulch. I’m talking bombproof! I want to go from a 50-70% evaporation situation down to 0% overnight. Boom! So with drippers installed at the bottom of our gentle earth shaping we set about sheet mulching with wet cardboard several layers thick. Dried manure goes on next to add nitrogen rich amendment in a form the trees will enjoy. With a lot of old hay on site, and clear we do not want to be planting grass everywhere, a 15cm layer goes on to be totally covered by later layers. Everything is lightly watered as we go. We are setting up a chain reaction and we want to reestablish life here. Life needs water. Next goes on more cardboard or newspaper, then a thick covering of cheaply sourced (but low quality) municipal compost. We moisten this and inoculate with our very high quality 18-day compost. We just set off a beautiful pile with a fox as a kicker, with very few bones left after just 5 days, and they crumble up in your fingers when you do find one. This is priceless material and will kick start the biology that will allow this whole thick mulch to become permanent soil. This diverse microorganism-rich resource, with perhaps 5000 different beneficial species of fungi and bacteria thriving, will kick start the regeneration of this area. On top of that goes a nice thick layer, perhaps 10-15cm of clean straw. We are looking not to grow anything we do not plant into this new soil, and we want to keep heat off the living portion and moisture in.
It’s an intensive ‘restorative’, nutritious mulch which will quickly be succeeded by living groundcovers. Intensive and possibly expensive, but the sum of the described interventions equates to a complete u-turn ecologically….
A road kill adult fox turns up at the right time — this seems to always
happen when we make compost!
5 days later, after twice daily turns in the first 3 days (necessary to keep on
top of the biological explosion!), and a lot has clearly happened. Part of
the skull and a couple of leg bones and small patches of fur are the only
traces, and these simply crumble up with light pressure already.
Into the mix we plant sweet potato cuttings to spread out and colonize this area, so we do not have to ever mulch so intensively again. This is a one-time reparative mulch in my mind. Some low cultivar perennial herbs will help us shift this to a fungal rich forest floor along with regular applications of fungal-optimized teas and annual additions of good aerobic compost and ethylene precursor rich mulch sources whilst we stabilize this new situation.
Now lets be clear, this is resource intensive, and so if we calculate to do this thoroughly for 200 trees it will be around Eur 8000. In my mind that is a great investment if you can put a cash value on the less tangible aspects of our ecology. Now we are in a biological succession leading the opposite direction to before. Desertification has u-turned and is now heading to reforestation. If we start intensively cropping interlane and on various levels then we can generate that expenditure back pretty quickly. So the next layer of design turns to creative ways to raise capital to invest. Then comes planting design, and we start to feel into the added cropping values to see how this fares. We can intelligently anticipate water reduction, based on pumps and degenerative technologies, and that initial large sum starts to feel a lot more comfortable.
If we can end up with living ground cover like this next year, but on top of the mini earth shaping and restorative mulch, then we’ve shifted things in a huge way. I wonder how strawberry would fare?!
One thing to bear in mind is the impact even dry lifeless mulch has when applied to the soil. A simple experiment with bottles, soil and dry mulch will show how putting the skin back on the earth leads to groundwater recharge. We’ve put more than the skin back on, we’ve dressed it up for the sort of conditions not seen around here for a very long time! Apply some of the patterned thinking above and you get some of the results. It may be free, it may start to build itself and succession does all the work for you. Pump in resources and time and effort and you can transform things very fast. In my mind in this land where desertification is underway, if I have the capital and resources, I will prioritize going the whole way and design in how to make full use of the rapid and developing ecologies. With things like mulch it is not worth going half way in many ways. Some straw is better than bare soil, but if you are getting weeds growing through and no rapid carbon accumulation, and the biology is not there to kickstart regeneration, is it not worth that little bit extra effort initially? My approach here is restorative, and I like to do a job well. On 40 Ha there is a lot to do, so I am in favour of getting this done properly once with nutritious amendment layers, complex biological inoculations, etc, and letting the plants take it on from there. I am not going to have to come back and weed, mulch or worry about this until the other cropping layers are established, when there is a totally different ecosystem budding and I’m not going to be worried at all!
In a dry landscape, anywhere evapotranspiration exceeds precipitation, we need to approach all scenarios with four clear anti-evaporation strategies. First is adequate mulching, then living groundcovers. Establishing shade and effective windbreaks are the remaining two. We apply all these strategies in our design work, and the next step involves a group design session around developing orchard polycultures for multi-layered diverse cropping. A new tree nursery is going to be necessary, as this is just one tiny aspect of the farm! With the possibility of date palm overstories, pomegranate, mulberry and sharon fruit interplants, much less light will be hitting the ground immediately. Add in cropping and nitrogen fixing lanes of eleagnus and globe artichoke and we are looking a little bit more like a forest already. Adding in useful perennial creeping groundcovers, dynamic accumulators and herb/pollinators and we are suddenly talking about a totally different level of beauty, production, function and form. Not bad for a morning’s effort! With the dramatic water reduction, conservation and storage developments going on in this scenario, I can comfortably imagine the establishing complex plant system and soils here using no more water in total than used currently with all this extra production happening too. A good investment in my mind.
We talked about the roles of grazing herbivores in brittle landscapes — with Holistic Management holding the keys to restoring carbon whilst improving production. It is a big and vital subject matter, but not enough time to diverge here. We are starting a large beef and chicken Polyface style operation over in Sweden next spring, so more to come in this regard another time….
Brad Lancaster’s eight design principles for dryland water management provide a useful framework for approaching the various elements on site, throughout which we might apply any number of strategies depending on all kinds of factors.
Begin with long and thoughtful observation.
Where is water flowing and how. What is working, what is not? Build on what works and start in places where something is already going on. Erosion features, guaranteed catchments and wetter areas will be useful.
Start at the top (highpoint) of your watershed and work your way down.
Water travels downhill, so collect water at your high points for more immediate infiltration and easy gravity-fed distribution. Start at the top where there is less volume and velocity of water. Water stored higher in the landscape allows us opportunity to use gravity alone to irrigate downhill.
Start small and simple.
Work at the human scale so you can build and repair everything. Many small strategies are far more effective than one big one when you are trying to infiltrate water into the soil. This is such an important idea. Small hand dug earthworks on the Northern slopes here will accumulate mulch and allow water to slow and infiltrate. With a bit more effort we can intensively mulch each existing tree and use this ‘edge’ to design and build in lanes of production trees integrating forest garden principles, row crop or grazing on contour, which can allow us to break down the overwhelming task of reforesting this landscape into small achievable steps.
Slow, spread, and infiltrate the flow of water.
Rather than having water run off eroding the land’s surface and taking precious topsoil with it, encourage it to stick around, ‘walk’ around, and infiltrate into the soil. Slow it, spread it, sink it. Understanding contour and using contour and off contour patterning is essential for controlled and functional water design.
Learning to use ancient, simple, modern and high tech. equipment for surveying.
Always plan an overflow route, and manage that overflow as a resource.
Always have an overflow route for the water in times of extra heavy rains, and where possible, use the overflow as a resource. Essential in creating larger earthern dams where loss of life or damage to property is a risk! We have to engineer to the 1 in 100 year rainfall event that could challenge the whole system’s integrity. These are long term features.
Understanding the patterns and the orders of flow of water are essential to
effective planning — here exploring the bigger patterns of watersheds and
getting to grips with the geometry of Keyline design.
Maximize living and organic groundcover.
Create a living sponge so the harvested water is used to create more resources, while the soil’s ability to infiltrate and hold water steadily improves. Our preferred strategy is a bomb proof ‘restorative’ mulch succeeded by living and yielding ground covers.
Deep, nutritious and biologically active mulches succeeded by living ground
covers can rapidly turn the situation around in a dry landscape. Reduced
watering, improved retention, better infiltration, less evaporation, moderated
temperatures, increased diversity, better nutrient cycling, soil structure
improvement, rising carbon levels, higher yields, better rooting plants, less
disease…. Well, you know about mulch already….
Maximize beneficial relationships and efficiency by ’stacking functions.’
Get your water harvesting strategies to do more than hold water. Berms can double as high and dry raised paths. Plantings can be placed to cool buildings in summer. Vegetation can be selected to provide food. Windbreaks, fodder crops, shade, the interactions can be endless. For example, in the image below we see one of the irrigation tank dams, 300 000 litres ready to be back filled with soil, planted intensively and a 3-4 species aquaculture system introduced. Storable protein and living, nutritious irrigation water. Apply our anti-evaporation strategies and you see truly that yields are limited only by the imagination.
Open air 300, 000l tank dam. How much evaporation are we losing? What
functions could this also be performing? Lets cover the exposed liner up….
This large tank dam could be providing stacked functions in so many ways.
We consider intensive aquaculture, the steps of implementing this, and the
possibilities of bypassing the leaking septics to create a WET system that
eventually feeds the entire site’s processed grey/black water into this
production unit, to be further utilized as nutritious irrigation water.
Continually reassess your system: the “feedback loop.”
Observe how your work affects the site — beginning again with the first principle. Make any needed changes, using the principles to guide you. Accruing tangible data will be a useful way to influence our own and other’s decision making. There is always some possibility to tweak things and up production with a little bit more work and engagement. In the scenario we are working in here, where the desired ecology several years down the line differs hugely from what we are working with now, observation and feedback loops are going to be essential continuously!
So these principles give us a context for approaching the land, which I would always approach working through the Keyline scale of permanence. Together these approaches for design are going to be very functional, organizing frameworks for the various strategies we might employ and the priorities we choose to hone in on.
It is important to reflect not only on the current climatic conditions, but really understand what this landscape used to look like before a long series of destructive interactions occurred. Some clear understanding of what will kickstart a beneficial chain of successive reactions leads us into considering the landforms we are dealing with. The topographic below details the current array of piping, pumps and ground sources on site, including the canal which offers a false sense of security regarding the future.
Accurately mapping water piping, pumps, etc, is vital. It’s amazing how many places
I go where there is no record of complicated and often redundant systems. Here
CAD mapping allows functional and accurate design to be layered together in
conjunction with GIS systems if appropriate.
With the idea of starting at the top of our ‘watershed’ we are looking to capitalize on areas where erosion features are already present, and ‘edge’ we can work with, or investigate useful sites for tanked/dam storage. The image below details ideal dam placements in the landscape, responding to the landscape features and based on watershed and catchment analysis. I quickly calculated this on a previous visit, and so we are looking with more detail at the proposal.
Initial catchment analysis and dam site identification
There is an idea to develop two separate systems at this point. Lower down in the farm there is a canal feeding to, you guessed it, a large golf course (previously for agriculture mainly) and this along with several wells supply the large majority of the site’s water. This is arguably a questionable source in the long term, and possible saline encroaching and salting topsoils ring bells here at what would have once been salt marsh flood ecology. By utilizing some of this water that is currently freely available we are investigating the effectiveness of a solar pumping system transferring this water to a tank dam right at the peak of the mount. That will supply 2- 4 bar pressure to run existing and future drip systems. The idea of the keyline dam system is to start to slow, store and utilize some of the land’s beneficial catchments and, over time, as soils build and evaporation strategies take hold, these interconnected storages can provide more and more useful and nutritious storages.
Utilizing reliable catchments, hard exposed surfaces, roads and roof surfaces, we can collect accurate data easily. Using conservative run off co-efficients throughout the watershed we can build up a useful and conservative idea of what to expect. Sealed catchment drains will help send water slowly and gently to our well placed water bodies. We want to keep these dams as full as possible year round to maximize their potential for diverse use and function in the landscape.
The tank dam on the mount is clearly the cheapest option for us here — buying tanks of the required volume are likely to cost 15k and upward, and the mount is already covered with hundreds of tons of rubble. Along with some of the excavated and less useful materials from lower dam sites this will make a useful wall construction for a lined storage, replacing many pumps and pipes with purely gravity fed water.
The important factors I would consider are the evaporation rates up here on the exposed mount where long term windbreaks will be necessary from the N and S sides. I would also consider the possibility of a 3- 4 species aquaculture system to lead nutritious water through the entire irrigation system. A matter for further discussion, there is also a similar size lined tank dam lower in the site I also consider suitable for intensive aquaculture. These lined large bodies, perhaps 300 000l lower down and smaller on the mount, can be back filled with earth to allow aquatic and sub marginal plantings and kick start the storage into a whole new way of life! Anti-evaporation in the meantime may include shade netting, plantings to cover the surface water and rafts that could house ducks, plants or simply shade. Many possibilities!
The next step with the earthen dams involves catchment calculations. By understanding topography and the landforms we are detailing with, we can start to piece together a picture of how much water flows through this landscape. Cleverly intervening and collecting from reliable sources as well as diverting water allows us to move towards dam volume calculations. In dry lands it is most effective to create a low surface area to volume ratio where possible to minimize evaporation and stabilize water temperatures.
Using conservative figures throughout the data and making dams smaller than ‘necessary’ allows us to keep the levels as full as possible, creating abundant and optimal ecosystems that can be developed and extended over time. Having identified keypoints in the landscape we then dig 3m inspection pits to see if we have the soil depth and useful earth resources to minimize the cost, impact and efficiency of the build. Not surprisingly we found easy digging in the expected places. The upper site has no useful clay content but instead of hitting rock like I would expect on the ridges and edges of the valleys we find decomposed limestone that cuts easily. This dam will need a GCL liner or back filling with suitable clay from lower down in the site. If we have the clay we may use a diaphragm style wall and filling up here.
Lower down in the landscape at the second site my initial feeling is that we should expect to find deeper and more clay rich soils. However, with the level of soil erosion indicated from older trees, one can never be sure what you might find. A pit here indicated solid and apparently uncontaminated clay from 2-3m with potentially useful clay between 1-2m. This opens up the possibilities to do everything considered so far with material onsite if the clay proves suitable. Here we may build a homogenous or zoned wall dam.
Determining what we are working with and how dams can be constructed involves testing, particularly the lowest portion of soil in the lower pit trench. Below are classic tests performed to determine suitability. The construction of an adequate embankment foundation is vital to the success of the storage. The dam wall must support the weight of water and wall itself without substantial settlement and be relatively impervious to excess seepage. Sites that have landslips, and to a lesser extent springs and soaks, need to be avoided due to inherent soil instability.
Various tests can be conducted to assess the suitability of our soil resources:
The Emerson test determines the behaviour of clays in contact with water and to what extent they break down in that contact. This test impacts heavily on the suitability of the site material for dam construction. Soil Dispersivity testing uses the Emerson Soil Dispersivity Method of analysis and classification:
Class 1 exhibits complete slaking in water. Class 2 only some slaking. Class 3 is registered after re-forming the sample, then after immersion and shaking disperses. Class 4 after shaking for ten minutes and left for 24hrs then disperses; Class 5 does not disperse after 24 hrs but does with the addition of Calcium sulphate (gypsum). Class 6 does not disperse after the addition of gypsum but displays some moderate slaking; Class 7 disperses after subsequent shaking. Class 8 completely flocculates after shaking.
Determines the proportion of clay, silt, sand and gravel through the soil profile of the test. Once tested you can get an idea of how much suitable/unsuitable material is in the proposed site.
Two tests – The plastic limit is defined as the moisture content at which soil begins to behave as a plastic material. A plastic material can be molded into a shape and the material will retain that shape. If the moisture content is below the plastic limit, it is considered to behave as a solid, or a non plastic material. As the moisture content increases past the plastic limit, the liquid limit will be approached. The liquid limit is defined as the moisture content at which the soil behaves like a liquid.
Soil is put through a #200 sieve to wash away clays and silts attached to sands and gravels to determine accurately the 15 Group Unified Soil Classification (USC) – which describes the proportions of gravels (G), sands (S), silts (M), clays (C), organic soils (O) and peats (Pt). When formally classified this provides the engineer/designer with the basis for designing the dam wall.
This tests the moisture holding capacity of the soil. The laboratory test determines the rate of permeability of moisture per centimetre per minute. This is simultaneously the most useful and the most expensive of the geotechnical tests.
Another field/home test called the “bottle test” is as follows:
- Cut the bottom off a 750ml soft drink bottle;
- Invert the bottle and 1/3 fill with the soil to be tested;
- Fill the bottle with water;
- If no water seeps through the soil within 24 hours then the soil has good water holding properties.
Investigation begins at potential Keyline dam sites — what are our earth resources?
Getting a clear look at the soil strata and taking samples for testing to determine
suitability for earthern dam construction
Once soil suitability has been determined we must consider bank construction, detailed overflows, outlet fittings and start determining the volume of earth that needs to be moved and the job can then be costed. We are looking for the minimal disturbance that maximizes the efficiency and safety of this work. It is healthy to be cautious throughout this process!
We are considering designing up the earthworks and timing the work to proceed the expected rains, so planting plans, mulch and seeding need to be thought through too to make use of this disturbance to kick start succession the way we desire it to go. As many people desire more knowledge and hands-on experience with designing and implementing this kind of system we are considering a 10 day practicum as early as November covering various aspects of combined Permaculture/Keyline approaches with a focus on hands-on and guided observation to really bring home the effective solutions that can change the erosion and desertification patterns of this part of the world.Comments (7)