Thursday, March 9, 2017
Phoenix ASH & Regrowth
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 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.