This is a two-part series post. Part I: Learning the basics of cover crops: find out about what we’ll be experimenting with this spring and fall, what cover crops are and how they can benefit your garden, what benefits they serve, and examples of what to use. Post II to subsequently follow.
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Table of Contents
A Year of Experimenting
This year is going to be such an interesting year. First of all, I’m growing food not only at our own house, but will be growing at my parents’ house as well. Secondly, this year is a year of experimenting. I’m implementing cover crops into our gardens, which I’ve never done before. I’ll be bringing you along to share what I’ll be doing.
Our soil at our home is a work in progress and it takes time for soil to heal after either being neglected or repeatedly abused with an array of chemicals (pesticides, herbicides, etc) and tilling. The fact of the matter is that using these chemicals to control weeds and pests destroys the soil’s ecosystem, kills everything that’s beneficial leading to the degradation of soil, and causes soil erosion. They’re actually counterintuitive because by keeping the soil healthy, weeds and pests are suppressed. Instead of remaining familiar with plants that correct these issues on our lawns and in our gardens, we’ve opted for an easier option.
As David Montgomery explained in his book Dirt: the Erosion of Civilizations, we’ve been battling soil degradation and erosion since we started cultivating our own food. He further stated,
“Although these problems are mostly of our own making and well within our power to solve, citizens, the media, and politicians don’t seem to take them as seriously as volatile financial markets, climate change, or any number of societal challenges. And yet how we treat land, how we treat the soil is fundamental to the health and survival of modern civilization.1”
He further discusses how archaeologists identified the link between soil loss and the decline or collapse of civilizations.
What are cover crops and why to include them in your garden
Cover crops are an integral part of regenerative agriculture, farming, and gardening. A cover crop is used to improve soil health; slow down soil erosion; help prevent weeds, pests, and diseases; attract beneficial insects; and enhance the soil’s water availability. It’s essentially a green mulch, or living mulch, that’s used to capture and add minerals back into the soil. These crops’ main purpose is to grow to replenish the soil and then are cut down to be used as a mulch.
Benefits of Cover Crops
Cover crops provide a way to reduce or completely eliminate the need to use synthetic fertilizers by adding organic material and minerals like nitrogen and phosphorus. They create a biodiverse environment for bacteria and fungi. After the cover crops are grown, terminated, and turned into the soil, they begin to decompose. The decomposition process releases nitrogen, carbon, phosphorus, and sulfur. The process also releases sugar from the plant that attracts bacteria and fungi. The bacteria and fungi attract beneficial insects, like earthworms for further breaking down. And so it forms a cycle! Decomposition rates depend on the crop that’s planted.
What Experts Say
By improving soil health, by using cover crops the Sustainable Agriculture and Research Education found in the national crop survey (2019 to 2020) in which “1,172 farmers participated that there was a large amount of savings involved as well. The survey revealed:
- higher crop yields in soybean and corn
- Savings in cost with the reduction of use of herbicides and fertilizers
- 52% of the farmers surveyed used green mulch
- 71% had better weed control
- 68% had better soil management
- 54% were able to plant earlier in the season.2“
Cover crops really do so much for the soil that they should be implemented as a common practice.
Additionally, cover crops add an abundance of carbon into the soil through photosynthesis. For the best outcome, it’s important to have a variety of cover crops. As Gabe Brown discussed in his book, “Dirt to Soil: One Family’s Journey into Regenerative Farming,”
“The more leaf area there is in a field, the more sunlight will be “caught”, and the more photosynthesis will occur. Dr. Christine Jones calls this photosynthetic capacity… The varying leaf sizes and shapes in a multispecies planting, along with the larger range in plant heights, will result in more sunlight-encountering leaf area, thus pumping more carbon into the soil.3“
He continues by further discussing photosynthesis rate, which is the speed (how quick) a plant turns light energy into sugar. The higher the photosynthesis capacity and rate of a plant, the better.
Suppression of Weeds
Weeds are an indicator of soil health and can be helpful in identifying an issue with soil health. They can point to deficiencies in the soil.
Here are a few examples:
- Redroot weed – sign of iron-manganese imbalance
- Moss – indication of low soil pH, too much moisture and not enough drainage, compact soil, and lack of sunlight
- Thistle – low soil fertility and open areas
- Nettle – low calcium
- Lambsquarter – low phosphorus, high potassium
Because cover crops are so tightly grown, they suppress weeds from popping up. They also provide a great source of nutrients thereby creating an environment that isn’t suitable for weeds. Plants that are high in biomass and grow quickly outcompete weeds for light, nutrients, space, and water.
Soil Erosion, Soil Aeration, Water Retention and Water Infiltration
Cover crops that have a lot of biomass have deep, complex root systems. Strong, healthy roots help prevent soil from becoming compact, thereby allowing the soil to aerate. Roots also release sugars, organic acids, and other compounds into the soil that promote beneficial soil microbes and inhibit plant pathogens. The microbes then increase carbon and nutrients cycling into the soil. Decreasing compaction of the soil helps with water retention which thereby prevents water from washing away soil.
Attracting Beneficial Insects
Many cover crops have flower blooms that attract beneficial insects like bees and butterflies. Not only do they attract insects above the ground, but below too! As previously mentioned, the plants release sugars into the soil that attract bacteria and fungi. The bacteria and fungi then attract earthworms.
Cover Crops to Use in Your Garden
There are all kinds of cover crops that can be used in the garden. Choosing the best one for your garden depends on the planting season and your local climate.
Examples of cover crops
Winter rye highly drought resistant and does well at loosening compact soil. It can tolerate dry, sandy soil and clay soil.
Buckwheat is a fast growing summer crop that helps to prevent erosion, outcompetes weeds, ability to access phosphorus, and attracts beneficial insects with its blooms. Since it’s quick growing, it’s an ideal crop for both fields and garden beds. It can tolerate acidic, alkaline, light, and heavy soils.
Crimson clover has beautiful crimson flowers, hence its name. It’s commonly used since it adds nitrogen back into the soil. It helps with soil erosion and can even be planted in the winter, if the winters are warm. It grows well in basically any type of soil except soils that have a high acidity or alkaline.
Sorghum-Sudangrass is a fast-growing, weed suppressing crop! It has interesting green and brownish looking plumes. Because it grows so quickly, weeds don’t stand a chance to pop up. It has an extensive root system and does well in summer weather. It’s especially helpful to compact farm soils or soils that are subjected to overfarming and tolerates growing in most soils. Sorghum-Sudangrass also disrupts the life cycles of many diseases, nematodes, and other pests.
Hairy Vetch has beautiful purple flowers. It’s a power nitrogen fixer and well known for its winter hardiness. Because of its winter hardiness, it is commonly used in colder climates such as Pennsylvania and North Dakota. Due to its vigorous growth, it’s a great addition to the garden to suppress weeds. It also helps to retain and absorb other nutrients besides nitrogen like phosphorus and potassium.
Partridge Pea has tiny yellow flowers that attract predatory insects like wasps. I’m not a fan of wasps and actually scared of them, but they do serve an important role in the garden. Predatory insects are useful since they mitigate and even attack pests, like getting rid of stink bugs. Partridge pea is a great source of nitrogen and helps with soil erosion.
In learning about cover crops, this had to be the biggest surprise. Okra can actually be used as a cover crop! Not only do they have flowers and edible pods, but they grow quickly, are drought resistant, and have deep taproots to help break up compact soil, which helps with water retention.
Mustard is known to be high in glucosinolates. Glucosinolates are a natural compound that gives off a pungent odor. Because of mustard’s pungent odor it helps to repel pests. It has little bunches of yellow flowers.
Cowpeas, or black-eyed peas, are a crop that have deep taproots. They are known to be a source of nitrogen and are a summer crop. There are two different types of cowpea plants – a bushy variety and vining. They not only help with nitrogen, but suppress weeds, build soil, prevent erosion, and are a forage crop for animals. Cowpeas don’t need a lot of moisture so they are a rugged survivor of drought and therefore a good crop to have on hand in drier climates. Since they have extrafloral nectaries, they attract beneficial insects like different types of wasps, honey bees, lady bugs, ants, and soft-winged flower beetles.
Other crops to look into: see Managing Cover Crop Profitability
If you haven’t read Dirt to Soil: One Family’s Journey into Regenerative Agriculture by Gabe Brown, you should seriously consider picking up a copy. The book is so informative and really highlights the need for us to do better with our gardening and farming practices.
- Montgomery, D. R. (2012). Dirt: The Erosion of Civilizations. United Kingdom: University of California Press.
- Magdoff, Fred. “CH 10. Cover Crops.” SARE, 29 July 2021, https://www.sare.org/publications/building-soils-for-better-crops/cover-crops/.
- Brown, G. (2018). Dirt to Soil: One Family’s Journey Into Regenerative Agriculture. Chelsea Green Publishing.