Soil health is a very complicated topic if you’re a soil scientist. For most home gardeners the major interest is in growing healthy food. You can achieve your goal of nutrient dense food by maintaining your vegetable garden soil as a vital living ecosystem. It boils down to a few basic principles. If fact, they can be grouped under 4 basic principles of soil health.
- Keep soil covered at all times
- Have a diversity of plants
- Reduce soil disturbance
- Reduce use of synthetics
This is very simplified. We’ll take a deep dive into each of these principles. We’ll explain them in depth and show how you can apply them to your own garden.
Keep Soil Covered at All Times
Soil erosion is a major issue with bare earth. Both wind and water move topsoil from your garden and deposit it on yours or a neighbor’s lawn. That might be good for the lawn but it decreases the fertility of your garden every time the winds blow or it rains.
The wind can make little “dirt devils” over your garden. What you are seeing is topsoil literally moving to a different location. When topsoil moves it’s not just the soil particles but microorganisms and nutrients attached to them. Keeping soil covered at all times reduces wind erosion.
Water erosion is more complicated than wind erosion. First, there’s the issue of runoff creating rills and valleys from your garden to adjacent land. Taking soil, nutrients, and microorganisms out of your garden. Second, there’s the damage caused by the impact of raindrops on the bare soil. A raindrop can hit the ground at a speed of 20 miles per hour. When it hits bare ground, it dislodges soil particles. Those particles can end up as far as 5 feet away. They end up clogging surface pores and affecting water infiltration. (1)
Of course, we need rain to grow crops. But when a 5-millimeter raindrop hits bare soil at a speed of 20 miles per hour it’s like a mini-meteorite. It dislodges some soil and compacts the soil left. When the soil dries the dislodged particles clog soil pore spaces and the site of raindrop impact is compacted. Both make a difficult environment for seeds to sprout.
When you leave last year’s crop residue and mulch on your garden raindrops hit those first. Organic material decreases the impact of spring rainfall on your soil and allows water to sink in instead of running off. Even the dead roots from last year’s tomato plants protect soil particles from being blown or washed away. Keeping nutrients and microorganisms in your soil.
The use of cover crops keeps the soil food web active and well fed while acting as soil cover, or soil armor. Keeping roots in the soil 365 days a year means you’ll always have a microbial community ready to decompose decaying organic material and convert it into nutrients for the next crop.
Plant Diversity Creates a Diversity of Soil Microorganisms
President Thomas Jefferson, over 200 years ago, knew the importance of plant diversity. He rotated his fields with vetch, peas, clover, and his heavy feeding tobacco. He knew if he continued planting only tobacco his soil quality would soon be exhausted. (2)
Of course, you’re not growing tobacco in your garden but there are a number of “heavy feeder” vegetables such as sweet corn and cabbages. Planting a legume such as peas or beans that capture nitrogen from the air next to your corn will benefit both. To find out how much different crops can benefit each other, check out this post on companion planting.
Thomas Jefferson also knew the importance of crop rotation. He had one cash crop, tobacco. But he grew 3 other crops from different plant families for a 4-year crop rotation. Those other crops served as a cover for the soil. He also saw that his plants thrived when he added compost to his gardens. He didn’t know what we know today about soil biology but he was feeding his soil microorganisms. (3)
The greater the diversity of plants in your garden the greater the diversity of soil microorganisms. There are three main ways microbial activity helps your plants grow disease and pest free.
- Microbes signal plants when a pathogen is in the area so the plant can activate its defense mechanisms
- Beneficial microorganisms simply outcompete pathogens for soil and plant root space
- Microorganisms increase the nutrient availability for healthy plants (4)
The interrelationships between microbiology and plants are both chemical and physical. Microbial activity on all parts of a plant – from the tip of a leaf to the tip of the root – protects the plant from insects and pathogens. Beneficial soil microbes fuel the . The major nutrient cycles for plant available nutrients.
Compost adds organic matter loaded with nutrients. But plants can’t access the nutrients on their own. Macro-organisms like earthworms and beneficial insects are visible to the naked eye and start the decomposing process. Where there are macro-organisms there are also microorganisms.
The macros break up the chunks of organic material into smaller pieces. Then microorganisms can break the organic material down into the different nutrients. Plants need the nutrients in compost organic matter to be in a form that is accessible. Microorganisms are critical for the conversion of organic nutrients into inorganic forms for plant uptake.
The entire soil food web, from earthworms to one celled bacterium, is more effective if they’re not disturbed.
Reduce Soil Disturbance
We have a tendency to think of soil disturbance as a plow in a field, but a rototiller is the same thing on a smaller scale. Rototilling your garden soil makes it look nice and creates a level surface for creating seed furrows. But it also destroys soil structure. Beneficial fungi are especially prone to destruction by tilling because they put out long one-celled strands, called hyphae, that hold the soil macroaggregates together which increase the nutrient and water available to your plants.
Beneficial microorganisms are busily decomposing any plant roots left in your garden. If you pull up those roots for compost, you are also pulling up and composting those microorganisms. It’s soil disturbance you may not have ever considered.
We’ve been taught that removing plant residue is necessary to control plant diseases. But let’s examine that idea further. Plant roots left in the soil are a source of carbon and other nutrients for microorganisms. When there is a diverse food source there will be a beneficial microorganism community filling the niches in the soil food web. There are always a few pathogenic microorganisms but, if the beneficials aren’t disturbed, they keep them in control.
Take your clippers to the garden in the spring and cut off the dead aboveground vegetation. That can go into your compost (as a brown, because it’s dead) but leave the roots in the ground. Remember, those dead plant roots are a major source of carbon and nutrients for your soil microbiology. Now you’re ready to plant using a no-till method.
A dibble (or dibbler) is a great tool for planting your garden, creating a limited disturbance of your soil. Never heard of one before? They come in all shapes and sizes. And if you’re handy you can make one in your workshop. This video explains the how and why of a dibble. (5) Enjoy!
You may hit a spot of old root when you’re dibbling your garden. Move the dibble a bit and you’ll be fine. That old root has a colony of beneficial microorganisms that will keep pathogens away from your sprouting seed.
Reduce Synthetic Fertilizer, Pesticide, and Fungicide Use
But you’ll only have beneficial microorganisms if you use natural soil amendments. Synthetics kill and disrupt the soil food web. The use of synthetic fertilizers short circuits the plant/microorganism symbiotic relationship. That affects other members of the food chain. If there are fewer microorganisms there will be a decrease in earthworms and other macro-organisms that count on fungi and bacteria as a food source.
Spraying for pests and diseases is often counterproductive. Do you seem to have the same disease and pest issues every year? The use of synthetic fungicides, pesticides, and herbicides, along with synthetic fertilizers, creates an inhospitable environment for all soil biology, including all the beneficials. Soon you’ll have no soil biology at all. That means you have to supply all the nutrients for your plant’s survival.
Surviving and thriving are not the same. We can add the nutrients we know plants need but the unknown combinations of organic matter, microbes, and nutrients are missing. Your garden will survive with synthetics. Those pesky disease and pest issues you keep having? There aren’t any beneficial predators to take care of them. So, you spray again, it’s a vicious cycle. But it’s a cycle you can choose to stop.
Your garden will thrive when plant nutrients are available through biological activity. Add compost to your garden this year and be patient. Be sure and leave as much of the plant biomass of your crops as possible in the garden. Remember to leave roots in the ground. Plant some cover crops to increase the number of days you have living roots in the soil.
The synergies between all the components of soil are necessary for true soil health and for nutrient dense crops in your vegetable garden. Soil scientists learn more every day about the microbial inhabitants of healthy soil and their relationships to the plants above and below ground.
Nutrient Dense Food is a Product of Healthy Soil
Your vegetable garden is an amazing place. Unlike a farm that may be growing only a few crops you’re planting a diversity of plants. Nurturing an environment that provides food and shelter for birds, beneficial insects, macro and microorganisms is key. Natural soil amendments will boost your soil biology. Kaytonik is a soil amendment that improves your soil for optimum plant growth.
Paying attention to soil health pays off in plants with higher nutritional value and less disease and pest damage. Watch as the earthworms come back, the predatory beneficial insects take out the pests, and disease doesn’t haunt your garden anymore. It’s all about the soil.