The primary foundation that makes possible the life we can all see around us from birds to bees to trees to people is the microbial soil-food-web, a vast unending network of microbial life that supports and guides all life on Earth.
Microbes live on every surface of the planet including those that are uninhabitable by any other creatures. Billions of microbes live in every scoop of soil on Earth. Our job as growers is to create the right conditions for healthy soil microbiology to thrive.
Every grower from farmer to gardener, from landscaper to homeowner has the same responsibility: to create the conditions that foster aerobic soil biology and plant health. Here are 5 practical tips for creating the proper conditions in your soil.
Tip #1 Keep The Soil Covered In Green
Utilize cover crops on farms and living mulches in the landscape to keep all the ground covered in green. Utilize mulches as short term measures to keep the soil covered in between garden plantings or annual seedings.
The reason we want to cover the ground at all times is because we want to avoid soil compaction. Soil compaction is caused in nature primarily by rain hitting bare ground.
When soil becomes compacted this eliminates air flow and causes anaerobic biology to take over thus reducing nutrient cycling and encouraging anaerobic / pathogenic biology. In other words when we leave the ground bare we end up starving the soil of oxygen and in doing so we invite disease and illness into our plants.
At home in the city and suburbs keeping the soil covered looks like ground covers between perennials, under shrubs, and around trees. Low growing shrubs with ground covers underneath can be used to cover slopes or flat areas in front and back yards, this will provide multiple layers of canopy and still allow for clear lines of sight.
On the in the veggie garden and on the farm this looks like cover cropping. White clover, peas, oats, vetch, red clover, rye, these are all good cover crops for a farmer. In veggie gardens white and red clover can be spread for very little money to cover walking rows and in between veggie plants. Cover crops help grow plant available nutrients in the soil due to their roots ongoing interactions with microbial life.
Clover for instance will grow in abundance of nitrogen in the soil due to an interaction between specialized aerobic bacteria and the roots of clover.
This interaction will create red nodules on the roots of the clover, if you see red nodules on your clover roots you know you’re producing nitrogen in the soil. If you don’t see red nodules on your clover roots, that’s an indicator that your soil isn’t aerobic.
Tip #2 Minimize Disturbance
Minimizing disturbance to protect and grow soil at home means eliminating pesticide use, tilling, plastics, landscaping fabrics and practicing low-impact gardening.
Human interference in the environment is the root cause of every crisis facing the planet. From climate change to ocean acidification, from mass extinction to ecosystem annihilation, human action in the environment is rapidly eroding the Earth’s physical and biological support systems.
Human beings inherently rely on these support systems. We all know about pollination and how the bees, butterflies, mosquitoes and other insects spread pollen from flower to flower thus allowing plants to reproduce and create fruits, nuts, and grains that we can eat. We also know about the water cycle and how all water on earth moves in great cycles moving into and through all living things and all ecosystems on the planet.
We all want to do right when we’re out in the environment, especially in our own yards. But what does right look like?
Pesticides kill healthy soil microbes by both directly poisoning them and by creating anaerobic conditions in the soil.
Pesticides include herbicides, insecticides, fungicides, nematicides, rodenticides, and so on, even organic pesticides.
These poisons all create anaerobic conditions in soil, and they all easily kill microbial creatures like nematodes, fungi, and amoebae. Since we’re trying to create aerobic conditions and grow aerobic microbes we can’t use any form of pesticide in our growing spaces.
Organic farming certification has a 3 year transition period because it takes a while to re-establish healthy soil microbes after the use of pesticides on growing spaces.
Remember, weeds love a soil that doesn’t have much fungi and pesticides kill soil fungi. Pull weeds by hand. Remove wasp nests with high pressure water from a hose with a nozzle. Treat infected plants or soils with compost, worm castings, wood mulch, and liquid compost extract.
Tilling destroys fungal networks, rips apart earthworms, rips apart nematodes, and creates compact anaerobic conditions in soil which encourage weed growth. Instead, turn areas by hand with shovels only one time upon installation of new gardens and beds. Turn only after topdressing with 3-6” of compost. Turning will leave large clumps of soil intact thus leaving webs of fungi as well as living nematodes and other life forms to both inoculate and be inoculated by the freshly added compost. The newly turned in fluffy compost will now sit under and around clumps of harder soil. After turning cover immediately with mulch or more compost and then immediately plant or seed.
Once you’ve turned your soil one time and incorporated compost in this way, and then planted enough to cover the ground in green, for the life of your garden continue to put compost and plants or seed into any bare areas until the ground is covered year round.
Low Impact Gardening
Begin allowing more weeds to grow in unused spaces and in the lawn. Bellflower, dandelion, creeping charlie, clover, black medic, purslane, and all weeds have soil building capacity. Weeds also help keep the ground covered in green, keep roots in the soil, clean and cool water, and feed pollinators. Many weeds are also edible for people, wildlife, and birds.
Weeds in the lawn can be managed for height via mowing and if you’re going to let weeds grow in your garden the general rule is to pull them before they get higher than the garden plants.
Over time weedy ecosystems transition into shrubby ecosystems and then into ecosystems with trees. This ecological succession can be helped along in your lawn by selectively letting your favorite weeds grow in places where they work for you aesthetically.
Eliminate Plastics and Landscape Fabric
Nearly all soils around the world including right here in the twin cities are contaminated with microplastics. Microplastics are the result of large plastic products such as packaging and landscape fabric breaking down into microscopically small pieces via sunlight and physical degradation.
Microplastics have been shown to attract toxins in the soil at 3-4 times greater rate than do regular soil particles such as sand silt and clay. This could lead to a poisoning of soil microbiology and the creation of anaerobic conditions.
Avoid the use of plastics in the landscape including plastic edging, landscape fabric, plastic netting, plastic gutters, vinyl siding, and plastic plant pots. Clean up plastic pollution when you see it in your neighborhood.
Tip #3 Keep Living Roots In The Soil
Roots of plants foster the growth of beneficial soil microbes, infiltrate and filter ground water, prevent erosion, slow down storm surges, and add organic matter to soils all while supporting the plants we love.
Multiple Layers of Canopy
Start to think of the underground in terms of layers of canopy much like we think of the forest or garden. We want shallow roots mixed in with roots that have medium depth and deeper roots too. This looks like hardwood trees with shorter trees and large shrubs beneath them. Under and around the short trees and large shrubs can be shorter shrubs and perennials as well as ground covers.
One all-native example might be an oak or maple tree planted with a shorter tree like redbud, serviceberry, and / or pagoda dogwood underneath it. Beneath and around these you could plant ostrich ferns, Canadian columbine, and wild ginger. Multiple layers of canopy are not only good for soil health, but they support birds and native pollinators while slowing and cool rainwater.
Grow Plant Diversity
Growing a diversity of plants will help us grow multiple layers of canopy while growing different types of roots that have different types of soil holding and soil growing abilities.
Plant diversity helps your landscape clean and filter water while remaining hardy in all types of varying seasonal and weather conditions.
Some types of plants do better when soil is wetter, some when it’s dry. Some types of plants do better when winter is colder, some when it’s warmer.
It’s best to have a strong diversity of native and / or edible plants in your landscape in order to have the capacity to grow healthy soil in any type of growing season we may have in MN.
We can even grow plant diversity and canopy layers in a lawn. Seeding with no-mow fescue and Dutch white clover seeds and letting native and naturalized weeds such as violets, Virginia waterleaf, black medic, wood sorrel, dandelion, and creeping Charlie take hold throughout your lawn will allow for multiple canopy layers that will help you have a greener lawn without watering in droughts and grow soil to protect against erosion and runoff better than lawn grass could on it’s own.
Mowing stunts root growth and limits plant diversity, mow as little as possible. Switch to mowing only once per month or only once per season after the middle of August to keep weed trees from getting too big while allowing for deeper root growth and a diversity of plants and pollinators to thrive in your lawn.
Tip #4 Integrate Appropriate Fauna
Plants evolved together with soil microbes and animals. Integrating the right type and amount of animals and soil microbes into your landscape can help more rapidly grow healthy soil.
Many homeowners are keeping chickens, ducks, rabbits, and even goats as livestock in the city and suburbs. Livestock animals create lots of compostable manure and bedding.
Field mice, voles, moles, rabbits, gophers, and squirrels help aerate soil by digging tunnels. If animals are in spaces where you don’t want them, consider using live traps.
Rabbits, squirrels, and deer are good at eating our garden plants, but they also help spread the seeds of important wild plants like wild strawberry, oak, and wild cherry.
Birds also help spread seeds and are excellent gardeners themselves. Birds will help plant all kinds of helpful plants including serviceberry, chokecherry, sunflower, mulberry, and wild grapes. If the birds plant trees on your property you might consider trying to integrate those trees into your landscape so you can invite more birds for years to come.
Microbes in the soil are the stomach for plants. Microbes process and release nutrients right on the roots of plants thus feeding and protecting plants from disease. The type of microbes you want to grow depends on the type of plants you want to grow.
Generally speaking we need to grow more soil fungi because many of our plants need a healthy variety of soil fungi as crop partners and soil fungal growth can be easily harmed through the soil compaction that results from many of our landscaping practices.
Other microbes such as nematodes, testate amoebae, and micro arthropods are also important in soil and are often missing from our grower managed landscapes.
Compost as well as bio-inoculants for nematodes and types of mycorrhizal fungi are a great way to introduce the appropriate microbial crop partners into your soils.
Red wiggler composting worms are incredible allies in growing soil in compost piles. Red wigglers are amazing soil builders because they have soil microbes in their stomachs that they spread throughout the soil as they move through the soil profile. While some folks are rightly concerned about earthworms in northern forests, red wiggler worms can’t live through the winters in MN.
Inoculate outdoor compost piles with red wigglers every spring. Utilize worm castings much like you would use compost as an inoculant to help feed and protect plants. Larger earthworms dig deep into the ground and are good for your veggie garden, perennial garden, lawns, and are even good at helping to restore damaged ecosystems. Remember not to bring earthworms of any type into forested areas, but don’t worry about them in your home landscape.
We know that bees and butterflies are good for our food crops because the pollinate flowers and allow for plants to reproduce. Mosquitoes, flies, and many other insects are also pollinators. What is good for plants health is also good for the soil. Encourage pollinators by having blooming native plants in your landscapes at all times of the growing season.
Our pet cats and dogs are evolved from felines and canines that lived in far ranging prides and packs.
In the wild canines don’t do much damage to soils because they roam far and wide. In our yards however, dogs pace up and down fence lines and gardens trampling and compacting the soil beneath their feet.
To avoid soil compaction it’s best to keep dogs out of gardens. Along fence lines and in dog runs utilize thick layers of wood mulch refreshed annually so as to avoid compaction and erosion.
Dog urine does major damage to lawns. If you have young dogs or a small lawn you may consider taking out your lawn in place of wood mulch.
Cats seem to be pretty mellow in the garden but they do hunt birds and mice which can be either a curse or a blessing depending on your viewpoint.
Dog and cat manure (as well as humanure) are compostable, especially using red wiggler worms in piles mixed with 80% woodchip and kept at 50% moisture. It’s not legal in MN to compost these manures in your yard and we don’t recommend it.