In this article:
May 10th, 2014
Over the past 6 months I have been carefully esigning and beging to implement a large-ish scale forage system for our animals.
I made a video in February about how the work was coming along, and giving a picture of how I anticipate the system developing.
The video also provides some background information to this update where I will be goin gover the large amount of work that has been done in the swale up until this point.
A Bit of Overview about Silvopasture and Swales
Silvopasture (literally forest-pasture) refers to a combination of both forestry and grazing systems. They come in many flavors, but are set apart from other systems in that the intent with silvopastures is the maximize both forage production and forestry related yields such as timber, fruit/nuts or fuelwood.
There are many ways a silvo-pasture can be structured and I will not go into great detail about all the posibilities, but the system we are implementing involves a "linear food forest" set along contour-swales (AKA Water-Harvesting Swales, with grazing activities in the regions between the swale.
Here how swale generally look and operate. Diagram taken Gaia's Garden by Toby Hemenway.
Contour swale are long, shallow depression laid out and dug along perfectly level lines (AKA 'contours') designed to collect water from surface runnoff or to slow down moving water features such as seasonal creeks so that the water can soak into the landscape and have a beneficial, life-enhancing effect - as opposed to an erosive one.
Swales are most useful in reforestation of degraded hillsides, and function to direct water to trees that would otherwise run off the bare soil and be lost to the valleys. In a healthy forest with a thick mulch of leaves or needles covering the ground, very little runoff occurs and swales would usually be unnecessary.
The main swale in this system, along with it's associated plantings will serve a multitude of functions.
- The swale bed provides an access way for cars and tractors to get inside the pasture without running over the productive grazing area.
- The swale's structure will passively stop and store water/nutrients moving downhill in the system. allowing those nutrients to be sequestered in the long-term storages of the trees
- Edge Locusts trees will support the pasture by providing nitrogen fixation, high quality "hangover forage and mast" (branches growing over the fenceline and locust pods falling into the pasture) annually.
- The trees will act and a windbreak downwind pasture, decreasing the evaporative stress on the landscape.
- Wood and herbaceous perennial provide an emergency stock of cut forage for bad forage years.
- fruits, nuts and locusts inside the fencing provide storable fodder crops for animals and food directly for people
- Coppiced locusts provide fence-posts for the ongoing maintenance of the fencing infrastructure
Trees and Shrubs Selected for the Swale Food Forest
Here a diagram originally from Permaculture: A Designers' Manual but modified by the Center for Sustainable Community showing the general pattern of planting downhill of a swale so that the taller trees are in the back with plants decreasing in height as you move downhill.
We will be planting in a similar way as the above diagram but with some particular modifications and different species. Our taller trees will actually be on the uphill side of the swale unlike the diagram. At the far back will be the honey-locust "standards" grown as a single trunked large spreading tree somewhere between 30-65ft tall.
just down hill of the locusts are black locusts managed as a coppice system to provide fenceposts to the 12 acre system and beyond. Harvesting of such a coppice will likely happen in a staggered fassion on a 5-20 year rotation depending on the specific needs. These trees will be anywhere from groundlevel to 15 feet tall and provide patches of light into the undersotyr where we can crop more forage for animals.
On the downhill side of the swale, gull sized fruit trees will eventually be established (once enough soil conditioning has taken place). Cider Apples, full-sized pears, mullberry, are all potentials for this large-scale system. These trees can top at out anywhere from 30-50 feet depending on the conditions and caharacter of the plants.
Moving downhill, large shrubs and small trees can be nestled into the nooks of the larger trees behind them. I anticipate many of these being nitrogen fixing plants to help support the nitrogen demanding fruit trees. Including:
- Pea-Shrubs (Caragana spp.),
- Sea-Buckthorn (Hippophae rhamnoides), and
- Goumi (Elaeagnus multiflora ).
Part of the design of this system is to have the resiliency to carry animals through a period of dry years. In service of this there are several cut-forage coppice crops included in the design such as
- the native Beaked hazel (Corylus cornuta) and
- Scouler's willow ( ), as well as
- mid-sized cold-hardybamboo ( Phyllostachys spp.),
Below these shrubs can be an assortment of smaller fruit, nut, berry, medicine, and forage producing shrubs and bushes or herbs that thrive in full-sun. I am also inclined to choose thorny species in order to deter browsing from through the fencing. This might include easy to propagate plants such as:
Constructing an inlet swale
The inlet and gabion. looking down the swale with the swale mound on the left.
As the video above shows, the first element in the system to be put into place was an initial inlet swale. This inlet swale was abuut 80 feet long and performs a handfull of important functions.
The water flowing out of the culvert can be moving very quickly. Our goal is to slow down and passify the water so that it ceases to erode soil and insted deposits it's silt and nutrients and soak into the soil.
So I dug out a splash pool for the culvert water's energy to disipate before it heads out to the swale.
I have yet been unable to fully complete the splash pool, and dig it out to it's full size given the amount of water which has been barrelling into it this spring.
However, the basic idea is the create a crater lined with large stones to safely absorb the waters energy and so it does not enter the swale (with it's soft, water absorbing edges) with much force.
The seasonal creek is not being totally diverted. a portion of it is being tipped into the swale and carried out along the pasture.
You can see in the second picture the permeable checkdam which is slowing the water enough to back it up about 6 inches where it enters the slightly sloped inlet swale which feeds the larger main swale.
The water coming out of the splash pool is very passive, clear (i.e. free of sediment) and is moving very slowly.
The soil here was very rocky and difficult to excavate. However, it did provide a lot of stones to help stabalize the bank, create the check dam, provide shade for the soil, collect heat in the cold months, and create small terraces on the steep hillside for both planting and walking.
looking in the opposite direction as the last picture, toward the culvert and splash pool. notice how still the water is.
The inlet was dug out, and the soil bermed up on the downhill side. This mound was mulched and planted with willow.
I completed the inlet about a month before the est of the swale was cut. It was passively sitting full of water for the whole time without any issues.
Standing on the downhill side of the swale mound looking toward the end of the inlet swale.
Planting a Riparian Buffer
I had the opportunity to host a Montana State University sustainable-agriculture student named Graham for an "alternative spring break" wherein he helped me with various permaculture related projects and learned more of the practical hands on components of agriculture. (Graham is actually Windward member Claire's brother.)
Here's Graham pounding in live willow stakes along the seasonal creek
He helped me with many projects in the pasture, including propagting loads of willow from live stake cuttings to create a riparian buffer around the creek, culvert and inlet swale.
A large scale buffer along a river in Iowa. Image courtesy of wikipedia.
What is a riparian buffer? It's usually a dense thicket of vegetation planted to help protect waterways by preventing livestock from eroding the bank, checking erosion in flood events, as well as capturing/filtering nutrients, fertilizer run-off, and pollution.
In our case we are looking to prevent our animals from getting access to the edges of a waterway - preventing compaction, erosion, and ultimately the gullying out of creek.
The willows and Dogwoods we're plantng will also serve as a source of cut forage for the animals and materials for further propagation in the future.
We will install and fortify specific areas of the creek to enable the animals to get access to the water. The buffer is to prevent the from getting access at any old place.
Cultivating the willow from live stake cutting is suprising simple.
We took local cuttings from an upland willow variety Scouler's willow (Salix scouleriana).
Scouler's Willow. Image courtesy of USDA PLANTS Database.
What is meant by "upland" is that it is more adapted to growing in a high altitude dryland forest conditions not associated with stream banks, unlike many of the other kinds of willow which almost exclusive inhabit the edges of waterways and marshes.
Upland willows are thus more drought tolerant, and in the case of Scouler's willow, much more tolerant of the harsher conditions here up on the plateau than any willow we would be able to find down by the river.
Scouler's willow also is a prefered forage plant for deer and elk, and thus also for goats sheep and cattle. So it will double as a coppiceable tree forage crop.
Wilderness.net has a great resource, The Art and Science of Restoration, which I used as a primary resource in this project. The NRCS also have lots of information about creating riparian buffers.
Live stake from Salix spp. is very common and has a high rate of success. This is because the plants create indeterminate buds throughout their body which can develop into either roots or shoots depending on the environmental conditions.
Here is a picture of the basic idea. Beveled living stakes pushed into the soil where they take root and start taking root. Images are borrowed from NativeRevegitaton.org
We used stakes of 3/4 to 1 1/2 inches in diameter cut to lengths of 4 feet, and beveled at the end for easy penetration deep into the soil where they will have easy access to water in their first summer.
We plunged a rock-bar into the earth about three feet to open up a hole for the cutting and then shoved the willow into the hole and pounded it in a deep as we could with a rubber mallet.
The tops were painted with a red latex paint, both the help the plants not dry out, and to help us easily see them.
Live stake cuttings are very common in areas of slope stabilization and quick revengetaion erosion prone hill-sides near water ways.
I hope to continue to propagate willow in various places in the pasture system. Including on some steep hillsides near out main entrance, and as a part of pioneering living fences and hedgerows.
Finding Contours with a Water Level
Intern Monica and I enthusiastically finding the contour.
Before any of the excavation and planting could begin, we needed to first find out where the contours led out across the landscape.
We did this with some home-made water levels. (Here is a good notes article from Walt back in 1997 espousing the virtues of the water level.)
The water level was made of uv resistant grey pvc electrical conduit, marked at every 1/2in, with a 25ft length of 1/2in clear plastic tubing zip-tied to the conduit. Simple but effective.
I double checked the level of the contour with a Berger pocket sight-level, by walking down hill of the flags until my eye level was level with the flags and turning in either direction to check all the flags lined up.
Planting out the Pioneer Locusts
Page helping to stage materials along the uphill side of the contour lines before planting.
Before the swale was cut, we did some initial planting of hardy pioneering nitrogen fixing forage, pole and fuel wood trees. These consisted of Black Locust(Robinia psuedoacaccia) and Honey Locust (Gleditsia triacanthos).
A look at a section of recently planted Locusts. A line of Honey Locust on the right and Black Locust on the left.
Black locusts are one of those special plants that are prized by homesteaders for their multifunctional benefits. They are heavy nitrogen fixers which produce a very rot resistant wood that is prized for construction and fence posts, as well as for firewood.
Their flowers are also an excellent nectar source for honey bees, produce a high-protein leaf that is loved by goats, deer and to a lesser degree cows and sheep, as well as a high-protein easily storable seed which is excellent for gallacious birds such as chickens and turkeys.
Black Locusts can be coppiced for fuel wood, posts and animal forage, and there-fore are commonly managed in sucha way as to provide a perennial yield for many many generations.
Honey Locusts produce similarly rot-resistant wood which has been used for fenceposts and sawn timber for a long time. The large straight- boled growth habit and yellow-red wood also make it a highly merchantable timber for construction and cabinetry.
Honey locusts produce a large sugary pod which has been a staple of silvo-pasture systems throughout the United States and beyond for the last two centuries. The sugar content makes them highly palleteable to livestock, easy to digest even for non-ruminant grazers such as pigs, and a prefered supplemental feed for cold-temperate dryland pastures which usually experience a "summer slump" in high quality forage production as the pastures tend to be drier and more fibrous as the season progresses.
A closeup of the Honey Locust in the tree protection tube.
The sugars help to jump-start the fermentation process in the rumen of grazing animals, enabling them to efficiently convert the high-cellulose summer forages into metabolizable energy.
The pods are easy to dry, and can be stored for many years. This is wonderful as it allows us to gather up pods in surplus years for use in the off-years of pod-production.
Both Honey and Black Locusts also produce a dappled shade which enables pasture to grow thickly underneath. This, combined with their nitrogen fixation and quality mast production make them very good candidates for any silvo pasture.
I propagated all of the Locusts onsite from locally available seed sources. Local seed is prefered because these plants have proven to survive and thrive in the conditions similar to the site of planting. The particular plants I gathered from recieve no supplemental water through the dry season, as so stand a high likelihood of serving the purpose of helping to pioneer this system.
The temporary strawbale greenhouse constructed to get the seeds started.
The mother trees were thornless or small-thorned varieties, which will hopefully make it much more pleasant to work with them as they grow up and fill out the upper portion of the main swale.
I initially dug the tree holes with Graham in early March. A few weeks later, when the locusts had 2 sets of leaves and were thus ready to plant out, we came back out and prepared the holes for planting.
That involved using a digging bar to open up a deep channel in the soil for their tap roots to easilt sink way down in the first year. The early and vigrous development of a taproot in one of the primary reasons why I both propagated the locusts from seed, and planted them out so early in their life.
We added a couple of soil amendments to each of the holes before we began planting. Powdered gypsum (calcium sulfate) was added to as a long term soil amendment, contributing to calcium and sulfer which will become biologically available to plants over the life of the plant through the efforts of soil organism.
Ruben digging the taproot hole and Pat making sure the gypsum is nicely powdered before we get started.
The gypsum will also help improve the condition of the pastures heavy clay soils by "flocculating" the fine particles into slight large aggregates - keeping the clay form packing up tightly. Thus increasing aeration and drainage, reducing anaerobic conditions and generally supporting the trees in establishing a solid root system.
We also added about a handful of well decomposed animal bedding (a mix of wasted hay, straw, manure and urine). This has a good, but modest amount of nitrogen in it to help nourish the soil and tree, but not so much as to send the tree a message to put on lots of succulent growth.
This is important because we want the trees to be focusing on building a solid root foundation in order to make it through their first couple of summers.
Here you can see the taproot of a 2 month old Black Locust seedling is over 4" long already and growing.
About a tablespoon of gypsum was incorporated into every handful of manure compost, which was then mixed into the native soil which can out of every hole.
Each plant was given a tree protection cage, 4-6" of wheat-straw mulch, and a stack of conifer branch mulch. The straw and woody mulch will help retain moisture, shade the soil, collect any leaf material that may come tumbling by, and to hopefully prevent trampling by deer by detering them from walking over the plants.
Illustrating a watering tube, and a closeup up of a locust with it's watering tube. Diagram taken from this informative article by David Bainbridge
" Getting Started with Efficient Irrigation Systems".
Each hole also recieves a tree watering tube made of a 8" long section of 4" diameter perf-pipe set into the hole.
Watering tubes are an inexpensive effective way for tree growers in arid regions facing a combination of 1.) low accessability of irrigation and 2.) a highly evaporative landscape which makes other surface irrigation inneffective (i.e. evaporation) or short-sighted/dangerous (i.e. salting up os soil).
Watering tubes eliminate evaporation by putting the water directly where the plants need it, in the root zone, while encouraging deeper root penetration as the water is filling the soil several inches underground as opposed to from the surface downward.
The tubes can be removed once the trees make it past the critical survival period the first few years, and can be re-used over and over again.
Preparing to plant a baby tree!
Excavating the Main Swale
Looking south along the first leg of the swale,
with the locusts on the right.
Toward the end of april we brought in a bull-dozer to cut the main tree planting swale in this system.
April and May are great times for us to do a lot of heavy earth moving. The soil is still moist and so is still easily moveable, but most of the residual moisture from snowmelt and rain has had a chance to percolate down deep into the soil.
We had the dozer first cut about 6in deep and one blade width wide along the back end of the whole length of the over 1000ft swale. The blad was tilted so that the soil fell to the downhill side. This demarkated the uphill side of the swale.
The dozer then turned around and moved another 1/2 a blade width of soil about 6in deep, along with mound of soil created by the first path. This demarketed the fill width of the swale - approximately 12 feet. The dozer worked all the way to the end of the swale.
The bull-dozer at work making the second pass.
Unfortunately, there was a significant amount of soil moisture still in a "draw" in a part of the swale. The dozer got stuck, and we had to spend about a half-hour jamming firewood rounds under the tracks untill it could get enough traction to back out of the swale and go around.
The dozer on the third pass.
We were unable to finish this section of the swale, and will need to come back at a later time and smooth out the ruts and get the swale mound shaped up.
Once the full width of the swale had been established, the dozer then cut the first pass deeper to a depth of about 1ft.
Similar to before, the dozer turned around at the end of the swale and cut the second pass deeper and moved the all the soil to the downhill side.
Being still a bit wet, the heavy clay subsoil did not break apart into fine particles. Instead it clumped together in large chunks which fell to the side of the dozer. This ultimately made the swale mound a lot more rough than I was anticipating.
THe bull-dozer is not capable of doing anything about this, as it's primary mode is to push soil. For many applications, the uniformity of the mound is very import. It is common for people to employ a Trac excavator with articulating bucket which can move in three dimensions. This gives a lot of control in shaping of mounds, slopes and terraces.
Something to keep in mind for the future is to wait a little bit longer into the season to do work like this if we are depending upon the tilth of the soil to passive form nice even mounds.
The finished excavation, looking backward (north) from where the first picture was taken.
There was an accumulation of soil at one end of the swale which we could not get the dozer behind to push.
We decided to push it all out of the swale bed up onto an adjacent bench that sits at the base of the slope leading up to our main entrance rouad. This slope represents the northern boundary of this system.
The mound will serve a couple of functions. Like all large berms it will tend to stop the downhill flow of water and leaf litter and passively build soil overtime. It is a great niche to plant a nutrient intensive plant that can make use of all the annual supply of nutrients.
The depression is significantly lower than the rest of the swale. Perhaps 4ft deeper than the rest. When the water enters the swale from the nearby inlet swale, it will first have to fill this depression and create a sort of pond. An unexpected feature, but something which I think adds a nice touch to this quiet little nook.
All in all the excavation took about 4 hours. Pretty quick for such a profoundly useful feature to help move this system into a greater level of productivity for our animals.
Seeding, Planting and Mulching the Swale Mound
The afternoon after the excavation took place, a seed mixture of hardy pioneering plants was seeded across the length of the swale mound.
The mixture was primarily dry-land Alfalfa, with a mix of Clover, Parsnips, Turnips, Rutabaga's, Mullein and St-John's Wort. These plants all have deep root systems which enables them to plunge deep within the swale mound to find water through the summer and thus start the process of building topsoil and organic material in preperation for more complex planting arangements in years to come.
As I said in my last article, it is important to put down seed immediately after earthworks are completed. When the earth is moved, it generally has a more open surface structure than normal. This provides a lot of small valleys and depressions for the seed to fall into.
As time goes on (sometimes in a matter of days) the fine soil structure will begin to collapse, covering the seeds and providing them the cover they need to germinate.
If you wait too long, the soil structure will already have closed up, and the survivability of the seeds is far lower.
After the seeds where cast, we gave the whole mound a scatter mulch of wheat straw to help shade the soil enought to keep it moist for the germinating seeds. A scatter mulch is not intended to cover all the soil, because the seedlings need to have immediate access to light.
Alfalfa seedlings coming up in the crevices of the swale mound, about a week after seeding
In the following days we added another layer of "rough" mulch (AKA "coarse woody debris")consisting of pine and fir branches. Fortunately, the Klickitat County Public Utilities District had come in the previous and cut down many trees which were growing under the power lines which happen to run through the center of the pasture.
straw and branch mulch on the swale mound.
In addition, fortunately or unfortunately, a very large Ponderosa Pine had fallen over in the pasture as well. The elder pine succumb to a trifecta of high-winds, saturated soils, and ice-accumulation in the crown. This is a fairl common occurance in our forest, particulalty for large tree in more open areas such as the pasture.
These trees provided enough material for us to put a layer of branches across the whole mound.
The branches will serve a couple of functions. They will act as a mulch and shade the soil. Also, because of their large size, they will provide shelter to the young plants from any deer that happen to wonder into the system in the next year looking for a snack.
Once the seedlings are large enough, we may also pile on more branches to the mound as a deterant for deer walking on the mound itself, since deer tend to avoid areas where there is un-sure footing. This has been successfully employed in other areas of out property. Primarily from
Slowly, these branches will be broken down by fungus and become yet another addition to the soil on the mound. Only with the branch soil, fungi will be more prevalent.
It is worth noting that woody plants tend to prefer a fungally dominated soil food web for a couple of complex and interconnected reasons concerning soil nutrient availability...I won't get into that here.
Suffice it to say, most woody plants readily form mycorrhizal associations with certain fungi in the soil where they recieve nutrients gleaned from the soil by fungi in exchange for providing the fungi's with energy in the form of sugary exodates. So more fungi usually means better tree health.
As of mid-May, the alfalfa seedlings are coming up with their first sets of leaves in the crevises of the swale mound, and a slew of comfrey roots have been dug in along the mound, but have yet to leaf out.