How Does Drought Affect Soil?

It’s a hot dry summer in much of the Northern Hemisphere, and along with the high temperatures and low rainfall come many questions about how this weather affects our gardens. We’ve written before about gardening during heat waves and other hot weather events, but today we’d like to take a look at a more specific issue: how does drought affect soil? Periods of dry weather have an impact on many aspects of gardening, but drought can cause some changes in soil that take time to remediate. Let’s dig in and learn a bit more about how drought affects soil and what we as gardeners can do about it.

Microbial Activity, Soil Health, and Drought

We know that drought is bad for plants—it denies them the water they need to stay healthy, inhibits their ability to absorb nutrients from the soil, and the high temperatures may inhibit pollination or flower-setting. This has long-lasting implications both in our gardens and in the broader world; studies show that droughts can alter plant diversity in some environments. The effects of this are easy to see, as the symptoms the plants display are generally visible to the naked eye.

Below the surface of the soil we find another set of effects that drought has on our gardens, happening on a microscopic scale we can’t see. Microscopic lifeforms in the soil—often called microbes—are a necessary part of the cycle of life. They help break down organic matter and create healthy, fresh soil; these are the little critters that turn your waste into compost if you’re lucky enough to have a compost heap. Like all living things, these microbes have a range of temperatures and moisture conditions that they need in order to thrive, and drought can inhibit their growth and survival. Without enough water, microbes cannot do their job in promoting and developing soil health, they cannot reproduce and thrive, and—as with most living things—a prolonged lack of water may kill them altogether. This can in turn alter soil health for years to come, and make it much more difficult to grow plants or reestablish  a healthy soil biome. By killing off healthy and desirable microbes, drought opens a space for other organisms to move in which may prove harmful to your plants and soil.

So, drought does more than harm your plants—it changes your soil biome and damages soil health. But what can we do about it?

Caring for Soil During a Drought

Soil health is garden health, and by being mindful of our soil during a drought we can help mitigate its effects both now and in the future. As with so many aspects of gardening, this comes down to taking proactive steps to protect and maintain our soil health year round. Here are some options to consider in order to caring for your soil during a drought:

• Good mulching can help protect your soil from both heat and direct sun, both of which are bad for soil health. A 1 inch/2.5cm layer of mulch combined with good use of soil additives and good watering practices can help sustain your soil through periods of dry weather.
• Speaking of soil additives, adding organic material like compost, yard waste, or composted manure to your soil can help it maintain good moisture levels while promoting or creating a healthy biome of microbes.
• Keeping weeds under control does a lot to help garden health overall and can also help your soil thrive when the rain isn’t coming. Weeds pull additional moisture and nutrition from your soil, competing with your plants and placing additional stress and demand on your garden soil during rough times. By removing them, you help everything thrive.
• Effective watering practices are a must in any garden, but during drought conditions they are especially important. Collecting rain in rain barrels, using drip irrigation for efficient water management and plant/soil health, and watering at the right time of the day are all great steps to take to save water while keeping your plants and soil as healthy as possible.
• If you have the room in your garden space, making space for native plants and wildlife is a helpful thing to do during a drought. Droughts can limit plant diversity in the local ecosystem and the lack of water causes stress for all living things. Making some space in your garden for local, native plants and supporting local wildlife is a wonderful way to ensure your garden helps support the natural world that all of us are part of.

Droughts and Garden Planning

Droughts and hot weather have become more common over the last few decades, and gardeners around the world have had to adjust their gardening practices accordingly by switching to heat- and drought-tolerant plant varietals, adopting new water management and soil cultivation practices, and shifting to new seasonal gardening schedules. Going forward, we’ll all have to stay informed, flexible, and adapt to changing conditions. Gardening is all about creativity, learning, and experimentation, and we’ll all have to cultivate those skills in growing seasons to come.