Of the various infrastructures needed to make a vegetable farm work, irrigation systems are my least favorite by far. They’re nearly essential, but just a complete pain. This is partly because of certain ethical/business choices we’ve made, which I will discuss below. Otherwise I just don’t like fussing with lots of components that need to fit and work just right, take a lot of time, and aren’t always necessary.
The source of water for irrigation matters a lot. County water lines are most reliable and give good pressure, but cost money which can really add up at the acre scale. Private wells are nice, but very expensive to drill if you don’t already have one, and have you at the mercy of the pump and other conditions. Drawing water from ponds is cheapest, but still requires some form of pump (gas, electric) which will also cost money to run and may be unreliable when you need it most. Ponds also put you at greatest risk of contaminated water, such as if wild or domestic fowl use your pond frequently and that water is piped right onto your lettuce. This is also true for farms that wash produce with water from a similar source. For organic certification, you have to do regular water tests to prove your water is clean, unless it’s coming from an already clean source like county water lines (which we use).
Irrigation in the field can be achieved in many forms. Easiest are the various forms of sprinkler, which can be set up with a simple garden hose and arranged to cover a wide area, then moved as needed. Multiple sprinklers, larger area covered. The major downside here is water efficiency, as they will lose a lot to wind, evaporation, and spotty coverage. Plus, it’s impossible to avoid watering aisles and other areas that don’t need it, and hard to target specific crops. Sprinklers are a great option for a small home garden, but can use a helluva lot of water at the acre scale. This is both an ethical concern, and an economic one if your water costs money of any form.
Various forms of drip irrigation are another answer. These involve plastic hoses with holes in them to let water out. The simplest really are just holey; fancier ones have pressure regulators at each opening so that the same flow emerges along the entire length, rather than losing pressure along a long line. These also come in various lifespans, from cheaper drip tapes that need to be thrown out every year, to heavier-duty hoses that can last up to five years. Here, too, are the ethical/economic concerns: do you save time and bother by using the cheap disposable hoses every year (acres of vegetables take a LOT of plastic hose), or do you invest in the long-term stuff which is far more work to carefully roll up in the fall and store properly every winter, but keeps your dumpster empty? Longer-term hose is also more subject to frost damage, a particular concern in our frost-prone valley.
When we started the farm four years ago, we invested in enough heavy-duty irrigation line to handle the market garden area. In 2007, this was a great call, as we had a very dry summer in which the farm recorded no meaningful rainfall from mid-June through mid-October. Since then, we’ve had two straight cool/wet years in which we never needed irrigation other than using hand-held hoses to moisten new seedbeds & transplants. This year, I fully expect to need irrigation at some point as I think it will be a hotter and drier (more typical) growing season, and we’re expanding our growing area significantly every year, so we’ll have some things to figure out.
When it comes to farm management overall, we absolutely refuse to use disposable materials like black plastic, one-year drip line, and so on. We’ve proud of the minimal waste stream coming off the farm, and of the smaller budget that results from not buying such things. So our irrigation choices will likely involve some combination of heavier-duty drip lines and sprinklers. We also use other methods to minimize water loss and need, such as heavy mulching on many beds to hold in moisture.
Still, as we enter a long hot spell, I can’t put off dealing with irrigation much longer. It’s always tempting to keep waiting, hoping for rain, in order to save a lot of time and effort. That’s what happened the last two years. With 1.5 acres under cultivation, though, we need to get this year’s system set up before it becomes an emergency and we spend all our time standing out there with a hose. So that becomes a looming project very soon.