This isn't the kind of subject I would prefer to write about, but rainless growing has unfortunately become the reality in Saskatoon this year. Thankfully, we are well equipped to press onward and most crops are still thriving. Let's take a look at the main strategies we are using to grow successfully despite the drought.
Before we dive into the strategies, here is a look at just how dry has it been. The grand total of rainfall is 85 mm or just over 3 inches in the last 10 weeks. See the bar graph below for a visual representation of the distribution. Thankfully, a large portion of that rainfall came at the end of May when we had lots of new seedlings in need of moisture, but that was far from enough, given that we've had exceptionally hot temperatures as well.
The level of precipitation that our vegetables need looks a little more like the chart below showing the same 10 weeks with the amount of rain that would fall in my dream world. Ideally, we want 1 to 2 inches of moisture each week during the growing season, and in the long hot days of July we are at the upper end of that range.
Since we have to eat regardless of the amount of rainfall, there's no point in just wishing for rain. In case you haven't picked up on this yet, I'm really not the type to leave my food to chance! If we want consistent results in the garden, we need to shift our attention to applying water efficiently from a dependable source and keeping it in the ground once it's there.
Water Application
We have two choices when it comes to water application. We can spray it overhead through the air and distribute the moisture all over our garden, or we can deliver that water straight to the soil one drip at a time in the places where it is needed the most.
Overhead systems have some advantages in their ability to cover large areas, but if water conservation is your aim, the whole premise of overhead irrigation is seriously flawed. Why would you want to start by spraying your precious water into the air and all over the leaves of your plants only to have it evaporate before it penetrates into the soil? Another downside of overhead irrigation is its poor accuracy. The water always finds its way beyond the garden, distributing unneeded moisture to pathways, weeds, patios, and whatever else is located beside your garden space. These two weaknesses of overhead irrigation systems make them a poor choice when it comes to water conservation.
The latter, drip irrigation, is by far the best choice in terms of water efficiency. Drip systems give us the control to place water precisely where we need it, and the water doesn't have to travel through the air or drip down through the plant canopy to get to where we want it, in the soil.
All of our plots are set up with a foundational drip system regardless of what crop we will be growing. That means regardless of how our crop planning changes each season, there is always a drip system there to rely on. That doesn't mean that we never pull out our overhead irrigation. Overhead systems still rank high in their ability to germinate directly seeded crops or keep heat sensitive crops cooler during the heat of summer, so when we desire those advantages, I will set up a temporary line of micro sprinklers to irrigate a particular zone. I like these low pressure sprinklers because they keep the water distribution close to the ground and concentrated in a pretty specific area, but there's still no question that water is wasted in the process. Therefore, it's not wise to depend on overhead irrigation as our only form of irrigation during periods of drought.
Water Retention
Our water saving efforts can't stop with our distribution choices, because that is only half of the challenge. Once the water has been applied, we can also help keep it there by increasing the moisture holding capacity of the soil and minimizing evaporation. Let's look at a couple of strategies we use to improve water retention.
The first course of action that we have been practicing since day one on our plots is increasing the organic matter in our soil. Individual soil particles vary in their ability to cling to water molecules, but the moisture retention ability of organic matter trumps them all. Since organic matter can retain up to 10 times its weight in water, we greatly improve the moisture holding capacity of our soil any time we add organic matter.
Does it matter what type of soil you are starting with? Not really. Different soil types all benefit in some way from the addition of organic matter. Sandy soils naturally drain very freely and organic matter helps them cling to more moisture. Silty soils compact too easily and organic matter helps them increase their structural integrity. Clay soils crack along the surface accelerating evaporation and organic matter prevents this cracking. I have seen organic matter work its magic on all of our different garden soils ranging from the lightest sand to the stiffest clay. In both cases, this organic matter works wonderfully to absorb moisture and slow evaporation from the surface of the soil. Note the significant difference in the two beds shown below. The one without compost seems like a barren wasteland.
The second major water retention strategy is to cover our soil. It could have the best moisture holding capacity in the world, but if we constantly leave it exposed to the sun and wind, it will still dry out eventually. That's why we always do our best to cover our soil with mulches, tarps, landscape fabric, or plants. Regardless of how or when they are used, these covers all help conserve moisture levels in the soil. Tarps and landscape fabric have the advantage of being super quick to apply to cover any bare soil temporarily. Mulches and plants have the advantage of also increasing the organic matter in our soil while keeping it covered. Used in combination these covers help us grow a ton of vegetables without leaving much exposed soil.
The photo below is a good example of how each type of soil cover has its place. The garlic beds against the fence are mulched with a thick layer of leaves while the double beds of winter squash in the centre are covered with landscape fabric. Leaves were the best choice for the garlic because they can be raked on and off at different times in the year when the plants are already growing and they can be laid easily within the many garlic stalks. Landscape fabric was the best choice for the squash beds because there were far fewer plants to work around and the dark colour of the fabric contributed to warming the soil which benefits our squash further.
Next Steps
That sums up how we have continued to produce consistently without rain. If your vegetables are suffering from the drought this summer, take a close look at your water application and water retention strategies. What areas are you irrigating unnecessarily? What areas of your soil are totally exposed to the elements? The goal is to create a garden space with no exposed soil and no water distribution in areas where it can't be used by your vegetables.
I have to admit, rain always seems to add an extra boost to our garden, but when those rainy days are few and far between, we still know we'll have plenty of food at the end of the season. I teach our soil management practices and irrigation system design in depth in our Seed to Table course, so if you're ready to check these two garden improvements off of your list, join me there. I leave you now with confidence that there will indeed be vegetables here, rain or shine.
