Nowadays, when we think of irrigation, we usually envision a series of hoses, perhaps some sprinklers and municipal water on demand. And, while that all might seem convenient, that’s not the ideal, is it? In a world where freshwater sources are dwindling, we ought to not be using our drinking water in the garden.
With all of the technology and literature at our fingertips, isn’t it odd that we use sprinklers to irrigate? Much of the valuable freshwater dispersed by them evaporates before it falls or lands on the driveways, stepping stones, and other non-garden locals to lie in waste. Like so many things we do, irrigation has gone the way of becoming overly-mechanized.
But, it doesn’t have to be that way. Creating efficient and effective naturally-irrigated gardens is still well within our capacities. In fact, in many cases, it saves our freshwater from washing into streets and gutters, becoming polluted and eventually causing problems, such as flooding. And, it’s easy.
Even in arid climates, we have the opportunity to design our gardens to maximize rain events, and that greatly reduces the need for frequently watering our plants. We can do this by subtly shaping the earth to spread and soak water into the soil rather than draining it away. We can do it by choosing the right kind of garden bed, utilizing basic water catchment systems, and using water-saving gardening techniques.
To put it bluntly, we are much better off using rainwater for our irrigation needs. It’s fresher water, not having been chemically “cleaned” as most municipal water sources are. The process of the rain cycle naturally filters the water. Additionally, rainwater is enriched with nitrogen (fertilizer) that it collects from the air as it falls. More so, it’s free, often arrives in abundance, and works well. (After all, forests and prairies don’t have sprinklers, and they do fine.)
The Natural Mindset
There are many simple landscaping techniques that can help with capturing and dispersing water across the garden. The main idea for irrigating naturally is that water needs to be slowed, spread, and soaked into the earth. When we do this, we prevent erosion and flooding while hydrating the entire landscape as opposed to only centralized areas (low spots).
That said, the idea, too, is to design our gardens around what is already in place, taking advantage of low spots, driveway runoff, and roof catchment. Instead of getting rid of rainwater as quickly as possible, we should look to harness and use it, benefitting from the hard surfaces and natural water reservoirs that occur on the land.
Earthworks is key to irrigating naturally. We can make small changes to the landscape to have water remain before it drains. Some of the most common techniques used are swales, berms, and terraces, all of which rely on contour (level) lines to pacify water flows. Otherwise, basins and other infiltration traps are great for natural draining lines.
- Swales are long, shallow ditches with level bottoms, and they are dug along contour lines, such that water moving downhill hits them and fills the ditch before going farther downhill and arriving at the next swale. These are great for mildly sloping land and taking advantage of hard surface (roofs and driveways) runoff, and they are extremely useful for growing trees.
- Berms are generally the result of swales. They are loose mounds of dirt put down the slope of ditches or basins. They can also be created along contour lines on shallow slopes to stop the water flow just like swales, allowing water to sink across the landscape. The mounds should be immediately planted with groundcovers and plants to stabilize the soil.
- Terraces are the solution for steeper hillsides, anything above a 15 percent gradient. They are level platforms created along contour lines. Generally, the inner part of the terrace, nearest the back wall, has a walking path and/or swale. The outer part of the terrace is planted with gardens. This is often how coffee and rice are grown.
- Basins are shallow, depressed areas of land with level bottoms. They are commonly put around the driplines of trees or where water naturally congregates, with trees planted around them. The basins are then filled with mulch so that water sits and soaks into them, becoming available to tree roots.
Final Design Tip
When irrigating naturally, it’s better to design the irrigation system first, utilizing the existing advantages to decide on the appropriate earthworks. Often swales and the upper side of berms can be filled with mulch or stones to make great, functional pathways. Once the water system makes sense, then start to figure out how to fit gardens into the space. And, makes sure to mulch the garden beds. This makes for very unique garden designs that are beautiful and highly efficient.
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