The Call, Column 48 – Water-Wise Gardening

6 06 2016

(June 5, 2016)

The Urban Farmer

Water-Wise Gardening

 

Despite the heavy rain in the forecast for today, I’m guessing that you’ve also noticed the sudden onset of warm, dry weather over the past few weeks. Though our southern New England climate has pretty much always been characterized by alternating stretches of warm, dry weather and cool, wet weather, the extremeness of this effect is being intensified by climate change. In the spirit of being well-adapted to the changing climate, and more generally with the important goal of resource conservation that underlies urban farming, today’s column is about a few key gardening practices and system-level approaches that aim to make the best possible use of water, both that which falls from the sky and that which is delivered through the faucet.

The name of the game is water-wise gardening. That begins with applying the best water you can as time-efficiently as you can, and ends with making sure that water stays where you put it for as long as possible. There are two classifications of methods and systems that we will discuss: gardening techniques that require little additional time or money, and more elaborate systems, that need some additional planning, but have a more pronounced benefit.

Let’s start with the so-called “low-hanging fruit”, simple gardening practices that have a pretty significant baseline effect with little overhead time or money:

 

  • Mulching. This is the single easiest and most effective water-wise gardening technique. By covering the soil around your plants with an inch or two of any fine organic material – grass clippings, shredded leaves, wood mulch, shredded newspaper, straw/hay, or even partially-broken-down compost, you can drastically slow down the rate at which the water evaporates. On a hot day, any un-mulched soil in my garden dries out within maybe 12 hours of watering or rainfall; mulched soil stays wet for at least a few days under the same conditions. Mulch also breaks down slowly into compost, which brings us to the next method.
  • Building organic matter content. Incorporating finished compost, manure, leaf mould, decomposed mulch, and other organic matter into your soil also drastically increases its water storage capacity with little effort. Organic matter contains a high level of what’s called “humus”, a not-well-understood organic chemical cocktail that is essentially the glue that holds our planet’s biosphere together. Among its many features, a high humus content is what gives soil its ability to store many times its own weight in water, thereby providing the plants’ roots with much longer-term access to water without more frequent watering.
  • Watering methods. Some measure of your water usage efficiency is the result of how and when you water the soil. By watering later in the evening or early in the morning, when the sun is not strong and the temperature is at the day’s lowest, the water will be able to percolate into the soil before being evaporated.
    In addition, much of the water that leaves the nozzle of the hose doesn’t make it to the soil, because it evaporates in mid-air. Following the above schedule helps to alleviate this, as does watering with the hose output as close as possible to the surface of the soil (that is, choosing those garden shower wands over sprinklers).
  • Layout of plants. There is a school of agricultural thought called permaculture, which theorizes that our agriculture performs best when it mimics the behaviors of natural ecosystems. Taking cues from this, you can maximize the soil’s moisture retention by being deliberate with the layout of plants in your urban farm. Specifically, by planting your main crops closer together than generally recommended, they will shield the ground from sunlight and slow water evaporation; a similar effect is produced by planting a “groundcover” of low-growing plants (i.e. strawberries, leafy greens, some smaller leafy root vegetables) amongst taller plants (like tomatoes), and has the added benefit of producing an additional crop from otherwise unused space. (Permaculture is a nuanced and very interesting set of theories, which warrants a few columns of its own sometime in the near future.)

 

Next, let’s talk about some not-very-costly systems that require a bit more planning, but have a more pronounced effect on your water usage:

 

  • Rain barrels. These are a great, self-sufficient way to meet your urban farm’s water needs, providing non-chlorinated, non-fluoridated water to your plants and animals while conserving our rapidly dwindling freshwater supply. Essentially, a rain barrel is any container (the bigger the better!) that is placed beneath a gutter downspout in order to catch and store rainwater. This water can then be used to irrigate your garden (especially with a drip irrigation system – more on this below). I would urge you to look at the much more in-depth column about building an urban rainwater catchment system that I wrote last June (you can find it here: http://tinyurl.com/zz9vh5y).
  • Drip irrigation. This is another planning-intensive but relatively inexpensive system to maximize your water usage efficiency. I am just beginning to install my own drip irrigation system in my garden, so I’ll tell you what I know so far. It is essentially a network of ½” and ¼” tubes, laid along the soil (hopefully on top of a nice layer of mulch). Water runs through the tubes and drips out of either small holes pre-drilled every few inches, or through specialized, fixed-flow-rate drippers that you install where you want. This network is initially connected back up to either a rain barrel or the spigot, first being filtered (to remove particles), pressure regulated (so that flow rates are predictable), and backflow regulated (which prevents a water cutoff from sucking the water back up into the spigot) by special attachments. For my large garden, I expect to spend $100 to $150 when all is said and done, and this system will save me 4 or 5 hours per week for years to come.
    This type of irrigation is beneficial because it delivers water directly to 1) the soil, preventing a lot of evaporation, and 2) the desired plants, reducing weed growth that results from broad watering. It lowers your water usage significantly, and (as mentioned above) does not require you to invest time every day or two watering, so is a huge time-saver!

Feel free to email me with any questions you have about how you might get started with any of the techniques or systems I’ve discussed above, or for more detail about starting a drip irrigation or rainwater catchment system.

My column appears every other Sunday in The Woonsocket Call (also in areas where The Pawtucket Times is available). The above article is the property of The Woonsocket Call and The Pawtucket Times, and is reprinted here with permission from these publications. These are excellent newspapers, covering important local news topics with voices out of our own communities, and skillfully addressing statewide and national news. Click these links to subscribe to The Woonsocket Call or to The Pawtucket Times. To subscribe to the online editions, click here for The Call and here for The Times. They can also be found on Twitter, @WoonsocketCall and @Pawtuckettimes.

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