For the last several months, I have been hinting at this
grand project I have been working on. I have felt it more important thus far to
lay the foundation to talk about some of the concepts being implemented onsite.
But I think I am in pretty good shape right now in terms of concepts being out
there, and before I jump into my next series of posts, I wanted to take a
moment to talk about the project I am currently working on.
The site is called Phoenix ASH & Regrowth. It is a half
acre site in the Sunnyslope area a little north of downtown Phoenix. The
project is an attempt to achieve as high a level of self-sufficiency as
possible while simultaneously repairing the ecosystem onsite. The project site
will also serve as a demonstration site to help promote these ideas and make
significant improvements on a wide variety of fronts including food production,
nutrition, flood prevention, urban heat island effect, air pollution, economic
resiliency, erosion control, biodiversity, and much more. To achieve this,
nearly everything we do onsite is to achieve one of two goals: 1) Restore soil carbon, and 2)
Promote biodiversity. While this may sound a little overly simplistic, these
two things, when working in conjunction, cause a cascade of healthy biological
functions that achieve everything else.
Let me take a moment to describe how this cascade works.
Increasing the amount of carbon in the soil does two things primarily. The
first is that it increases absorption of rainwater. This increases biological
activity and helps mitigate flooding. The second is that it increases the
fertility of the soil. As I have explained previously, carbon in the soil feeds
the soil biome and increases the fertility of the soil and the availability of
nutrients in the soil. By increasing the available moisture in the soil and fertility
of the soil, plant growth is encouraged. Remember, as a gardener, my job is not
to take care of the plants. My job is to take care of the soil and the soil
takes care of the plants.
Once we have widespread growth of plants, we move to the
next level. As I have already mentioned, the driver of ecosystem processes is
the cycling of living matter from one organism to the next. This is where
diversity comes in. Different organisms make use of different food sources and
bring different benefits to the system. Rather than trying to dig through the
science of biological systems, most of which doesn’t really exist yet (don’t
even get me started on the faults with reductionist thinking employed by modern
science), it is best to let the ecosystem find its own healthy equilibrium. We
do that by including everything in the whole. There really are no weeds. The
only caveat is that they must provide more benefit than they detract. So a pine
tree was removed from the site because all it provided was shade. Oleanders
were removed because they are highly toxic. And there are a couple of weeds we
remove because of toxicity. Otherwise, everything is welcome.
Once the plants are growing, each one is valued for the
benefits it brings. Edibles are harvested for human consumption. Grass and
forbs are used for forage for the animals. Dead leaves and grass are harvested
for compost. Trees are pollarded to provide wood to build more soil. At each
level, the plant material runs through its cycle and is returned to the soil,
increasing soil carbon and helping plant growth and diversity.
So let me talk for a moment about the various methods we
employ onsite to achieve all of this:
Holistic Management, as taught by the Savory Institute, is
more of a guiding principle. Everything we do is viewed through the lens of
Holistic Management and its principles. It is through Holistic Management that
we can make the best decisions for how to weave the myriad methods together
into one cohesive structure. The site also serves as the Arizona Savory Hub
(ASH) and the first urban demonstration site for the Savory Institute. We are
very excited to demonstrate that Holistic Range Management, which is typically
managed on large tracts of land in rural areas, can be applied in an urban
setting.
Permaculture
Permaculture is another guiding principle. The permaculture
core principles are also core values and guide what we do and how we rebuild a
complete ecosystem onsite.
Animal Impact, as described in Holistic Management is an
important part of how nutrients are cycled through plants and back into soil.
Right now, we just have chickens and are using them to process forage and
create compost. However, long term plans include goats and sheep, and maybe
even miniature cows or rabbits. Each animal will have its own impact on the
ecosystem, improving diversity and nutrient cycling.
Organic gardening, in its ideal form, builds soil carbon,
reducing the need for synthetic fertilizers, pesticides, and herbicides. By not
using chemistry to manage a biological system, the biological system is allowed
to flourish, encouraging diversity and growing topsoil. Everything we do onsite
at Phoenix ASH & Regrowth is organic.
While some of the organic matter is either processed in
place (as in animal impact) or allowed to lie where it falls, much of the
organic matter produced onsite is processed through the composting facility
onsite. This turns decaying organic matter into high quality topsoil more
rapidly so it can be spread back out where it is needed most. In addition, we
use the chickens (Animal Impact) to process the compost. This allows the
chickens to feed off of whatever they deem edible in the compost, including
insects that are attracted to the rotting material. It also allows their
droppings to be immediately incorporated into the compost. This helps the
compost get hot and complete its cycle quickly. And when it is time for the
compost to be turned? The chickens help with that, too.
At just 9” of rain a year, Phoenix is a desert. But with
careful planning and a little infrastructure, the rain can be stretched really
far. To do, this, we use two primary strategies at Phoenix ASH & Regrowth.
The first is rainwater barrels. There are two rainwater barrels on each of the
three buildings onsite. The two smaller buildings have smaller, flattened
barrels that sit up against the building. These each hold a little over 500
gallons. On the largest building, there are two larger barrels, each holding
about 2600 gallons. The smaller tanks are perhaps a little undersized for the
areas they catch, and the larger tanks are a bit oversized. However, with a
little planning and some plumbing, we are able to drain the smaller tanks into
the larger as they fill up, assuring that no rain is lost. This water is used
to water the gardens.
The second type of rainwater harvesting comes from offsite
flow, or water that is flowing onto the property. The property has a wash
flowing through it. While this was a major problem for previous owners, it is
seen as an advantage at Phoenix ASH & Regrowth. With a little regrading,
the site was turned into a series of retention basins. As each retention basin
fills, it overtops into the basin below it. By doing this, all, or nearly all,
of the offsite flow can be captured and stored in the ground. This has the
added benefit of reducing downstream flooding. The best part is that the first
basins built are already growing lots of vegetation and thus building soil
carbon. The change in water infiltration is already visible, with no water
standing in these basins a mere 24 hours after a big rain. The newer basins,
which haven’t had much of a chance to grow vegetation yet, take 3 or 4 days to
drain, even though they get less water.
Nitrogen Producing Trees
In desert ecosystems, and in particular degraded desert
ecosystems, there is often a lack of nitrogen in the soil. This can be a
limiting factor for the growth of plants and thus the ecosystem as a whole.
Nitrogen producing trees, such as palo verde, acacia, and mesquite can make a
big difference in this area. Not only do they fix nitrogen from the air and
make it into a usable form, but many are well adapted to dry climates with poor
soil. They are drought tolerant and fast growing.
As the trees grow, they produce a great amount of biomass.
Every two years, the trees at Phoenix ASH & Regrowth are pollarded, and a
few select trees are coppiced. The branches and twigs that are cut off are used
for a variety of purposes. They are used as feedstock for growing mushrooms, some are used to produce biochar. The bulk are chipped to either produce mulch
for various areas around the site or as a bulk carbon source in the compost
bins. The biomass produced by pollarding and coppicing becomes a large portion
of the biomass we use to feed the soil.
In addition, trees typically have a root structure that
mimics the size and extent of the canopy above. When the tree is trimmed back,
the tree abandons roots and pulls back, adding as much carbon down in the soil
as is harvested from above.
Some of the branches that are either trimmed out or are the
result of random pruning throughout the year are used to create new garden
beds. This use of hugelkultur adds a long-lasting source of carbon to the soil
and provides a lasting source of food for the soil biome where it is needed
most.
Woody debris that is too big for the chipper, unusable for
mushroom feedstock, or otherwise scrap material is processed into biochar. The
biochar is added to the compost. Once there, it collects nutrients through the
processing process. Then it is added to the soil with the rest of the compost
where it is used to improve soil quality in perpetuity.
Growing mushrooms is difficult in the desert, but it can be
managed. Mushrooms are used in the intermediary process between wood chips and
soil creation and provide an additional product. We are also working to find
ways to use mushrooms to improve degraded areas of the site. This is a
technology that has a lot of potential and we are working on finding a way
around the challenges to best make it work.
Phoenix ASH & Rebirth is located in a very brittle
environment and the bulk of the site is being managed with this in mind.
However, many of our common vegetables require quite a bit more water, thus
necessitating a non-brittle microclimate. In this interest, we are looking for
technologies that help use the water resources available onsite to their
maximum utility. Aquaponics has some great potential in this respect, being
particularly efficient with both water and nutrients. However, as a soil-less
technology, it doesn’t fit as well with the goals of the site. We are exploring
other options to improve the technology to be more organic.
As you can see, we have a whole lot going on for just a half
acre. But combined, these techniques work closely together to make some
significant changes in a degraded environment. Please help me in spreading the
word. If we can turn a half acre in downtown Phoenix into a productive food
forest and organic farm, it can be done anywhere. We just have to have a way to
get these concepts out there and teach people to implement them. This world is
fixable, and it can be done using the techniques provided to us by nature.
Let’s get on this.
