“We never know the worth of water till the well is dry”. ~Thomas Fuller Gnomologia: Adagies and Proverbs
This was my first formal class for the “Growing Food in the City” certificate (partnership between Burnaby Continuing Education and Gaia College).
In a place where most of the food production happens during the dry season, where water restrictions have become common and climate change threatens to extend both the heat and the dryness, being “wise” when managing water is a must for every gardener.
Water is Life
This is an obvious statement. Yet, we treat drinkable water as if is as good for flushing our waste, washing our clothes, cars and dishes as it is for drinking or watering a garden.
Water, however, is not only necessary for plants in the garden: if there is not enough water both in and out the soil, the microorganisms as well as the insects and animals that form the entire ecosystem will weaken or die.
In our climate (Western Coastal Canada, specifically BC), “natural” ecosystems are adapted to a pattern of rain through September to mid June and dry summers from mid June to August. These systems would not normally need any artificial design, “management” or irrigation as their plants, animals, insects, etc. are all adapted to these natural cycles.
But growing food is different: most of our diet consists in annual vegetables and fruits, many of them not indigenous from this region. No garden management will completely avoid irrigation under these circumstances: when you don’t have water for one, sometimes (like last year) two months, there is no way your vegetables and fruits will survive without some type of (artificial) irrigation…this is somewhat hard to swallow for those advocating for more “natural” systems, and a sticky issue around water restrictions: how are you supposed to make urban food production to happen when your water use is restricted to a few hours a day and treated at the same level as washing a car or flushing a toilet?
Managing Water Wisely
The main point of managing water in your garden is to manage it as a whole system, and not something affecting only plants. Taking a “designer” point of view changes the perspective from “responding to problems or symptoms” (i.e. trying to “fix” water scarcity with water restrictions) to proactively re-designing the systems so they provide what we expect from them…in turn regenerating and replenishing instead of just “saving” water…
The first step on any design (garden or any other type of system) is observation. In permaculture, we call this principle “Observe & Interact”. Things you may want to observe (and interact with) include:
This observation is important, not only for the design or any garden arrangement and/or irrigation system, but for the overall design of the entire system, be this a small backyard, containers, a community garden or a vacant plot.
Once the observation (and interaction) has guided you through what is currently happening (what are the assets and risks of your landscape), then comes the actual design:
In permaculture, water is considered a flow of energy, such as sun, wind and many other forms of flow/energy.
As such, there are a few things you can do with a flow: you can capture it, store it, you can channel it, you can block or restrict it or you can allow it to freely flow.
Each of these options will have a different consequence in your system, and many will imply a physical re-distribution or even creation/building of elements in the landscape.
It is also important to understand how nature stores water and how it eliminates excess: nature stores waters in the soil, in pants and the many creatures being part of the soil web. It also stores it in ponds, underground wells and streams. Nature eliminates excess of water through drainage (gravity plus type of soil/material, such as rocks or sand), evaporation and through plants processes (photosynthesis, respiration, etc.)
Simulating Nature we can “solve” many design problems in our gardens…let’s see how that’s done:
As mentioned above, soil type highly influence the compactability, drainage, water holding capacity and infiltration rate of a given soil.
Here is a table showing the relationship with each type of soil:
|Compactability||none to moderate||high||extreme|
|Water Holding Capacity||poor||excellent||excellent|
No matter what you add (in terms of sand, clay, etc.) you can’t change the basic type of the soil you have. However, all these processes are improved by the work of organisms in the soil: they aerate, increasing the air content, open spaces, increasing the drainage/infiltration rate and produce a “glue” that allows for water holding capacity, all this by reducing compactability…
As these organisms (worms, insects, small critters, bacteria, fungi, etc.) are alive, all need “food” (organic matter) and water to function!
Living soil is a structure created by living organisms: a spongy structure that can increase water retention and infiltration as well as make nutrients (and water) more available to plants. Clay, silt and sand cannot “arrange” themselves, but organisms can: they create an “habitat” (much like we humans create cities and build homes and roads) and is this habitat what makes soil alive…these organisms all feed on organic matter (OM): leaves, twigs, rest of dead plants and other organisms…the more you feed them, the better soil they’ll make for you, changing the structure of the soil and its behaviour in regards to plant-available nutrients and water.
You can add OM with:
Some of the benefits you’ll have when adding OM include:
Water collection is an option, but how effective this is will depend on many factors, starting with the climatic patterns of the region you live: in the Lower Mainland in BC, we have rain from September to mid-June. Any rain barrel will collect between 40 to 60 gallons, which may be consumed during the first week of the dry summer (or less, depending on the crops you have and the size of your garden)…while rain barrels are a great idea if you plan to use the water at home (let’s say, for toilets and washing dishes, to avoid using too much of the municipal water), they may not be the most efficient way to collect water to use in our gardens through dry summers.
So how else can you “collect” water?
Remember, the soil is the best place to “store” water: you can do this by minimizing hard surfaces, increasing water holding capacity adding OM as mentioned above and mulching
As mentioned at the beginning, we can’t avid irrigation unless we change the food system entirely and become hunters and gatherers again, following the seasons and eating only perennials. The problem with this is overpopulation: if each and every human being on earth decides to only eat perennial, seasonal plants, there wouldn’t be enough for everyone. Until a bigger (and necessary) change in our food system happens, we need to deal with the fact that most of us eat annuals and annuals require artificial irrigation.
Some irrigation methods with their pros and cons are:
Sprinklers/ spray heads
This method resembles nature’s way
Some of its limitations are:
This may be the most used in home and container gardening, even community gardens where hoses are long enough and available.
They are more time consuming but also more precise, as you can have a closer relationship with your plants and soil and apply water where is needed. They also allow you to spot problems faster.
When placed on the top of mulch, most of the water drains to the soil: you then miss watering the OM you just added and the entire idea of mulching is lost (water doesn’t go “upwards”)
This is even more concerning when soaker hoses are placed under the mulch!
Another issue is that the wetting pattern will be different depending on the type of soil you have. This means the water may only move a few inches sideways but will leave all the rest dry: what about the organisms and roots in those areas? How would they get water?
Drip irrigation has all the problems soaker hoses have adding the fact that they irrigate on intervals, so the water is not even continuous. Depending on the type of soil this may be a real problem as water may drain too fast before the next comes in.
In both cases (drip and soaker hoses) there is an issue with toxic salts accumulating on the sides where water is being applied, so the soil will have to be manually flushed periodically.
Managing water through plants
Some ideas include: grow more perennials (perennials also capture carbon, something annuals can’t do. Annuals are energy-intensive in many ways, including the time and resources you need to put in to get some food out)
Other ideas include: increase flowers and herbs in your diet (many are perennials or at least self seeding); use succession and polycultures grouping plants with similar water needs together; use multi-layered vegetation to create canopies and shade and retain/save more water; grow cover crops and incorporate them as green manure to regain the water they’ve stored, etc.