If soils could speak, some would say they are exhausted, while others would say they are enjoying perfect health. But what would the soil in your garden say?
The best thing with soils is that they are great communicators – your garden yields or the physical appearance of your plants will tell whether your soil is healthy.
But why wait until you have grown your plants only to realize that your soil is unhappy? It’s time to consider cover cropping!
So, In this article, we shall begin by defining cover crops. Afterward, we shall look at the different types of these crops and their benefits in the garden.
Table of Contents
What is Cover Cropping?
As the name suggests, cover plants cover the soil for different reasons. Unlike your main plants or cash crop, cover crops will give you secondary benefits like preventing erosion and adding nutrients to the soil.
However, you will need to note that cover crops have their needs, like your main crops. That said, below are some points that can guide you when choosing your cover crops:
- What you intend to achieve
- Which cover crop species can grow successfully in your climate
- Whether they will fit your garden
- How to plant, maintain and terminate the field crops
Cover Crop Types
Cover crops can be categorized into three classes depending on their properties and use: legumes, broadleaf non-legumes, and grasses. In most cases, these crops serve multiple purposes at the same time.
Legume cover crops
Legumes are famous for enriching the soil with nitrogen. Also, the bigger the plants, the more nitrogen they can fix.
Additionally, their vigorous taproots help loosen the soil, which means the soil will be well aerated and that your main crops can quickly access nutrients.
Examples of legumes include white and crimson clover, fava beans, cowpeas, hairy vetch, and alfalfa.
Broadleaf non-legumes
These cover crops help hold soil in place and make green manures. Also, these plants will not require a lot of termination efforts since they often die in severe winter.
Examples of broadleaf non-legumes include forage radishes, mustards, marigolds, turnips, brassicas, and others.
Grasses
Grasses include annual cereals like wheat, buckwheat, rye, corn, oats, barley, etc.
The best thing with grasses is that they grow very fast, and the residuals they leave behind are easy to manage. Also, grasses have a strong fibrous root system that protects soil from erosion.
Cover Cropping Benefits
Now that we have defined cover cropping and seen several plants that can be used as cover crops, let’s now see the detailed benefits of covering your garden soil.
Added nutrients
Cover crops can help improve soil health in the following ways:
- Legumes like peas and clover combine with Rhizobia bacteria to pick nitrogen from the air and convert it into forms usable to plants.
- Nitrogen will help your main crops to develop a good structure, process nutrients, and create chlorophyll. Without nitrogen, your plants won’t grow taller or produce an excellent crop yield.
- Other cover crops like tillage radish, oats, and annual ryegrass are scavengers; their roots can reach inaccessible or unused nutrients in the soil and use them up.
During the termination of these crops, they leave behind all the nutrients they have gathered, thus benefiting your next crops.
Scavengers are great options since they pick up all nutrients in the soil, thus minimizing nutrient losses from soil erosion.
- Cover crop mixes add organic matter to the soil when they are decomposing. Soil organic matter helps feed essential soil microorganisms, which help promote soil fertility.
Additionally, organic matter increases nitrogen levels in the soil and enhances the ability of the soil to trap other important nutrients like calcium, potassium, and magnesium.
Also, soil rich in organic matter require lesser nitrogen fertilizer.
Moreover, cover crops fall under the four key principles recommended by USDA for improving soil health, as you can see below.
Table 1: Principles for improving soil health
Principle | Details |
Minimize soil disturbance | ● Limit tillage; for example, you can use cover crops to suppress weeds, thus lowering tilling needs |
Maximize soil cover | ● Plant cover crops |
Maximize biodiversity | This helps break disease cycles, promotes plant health, and attracts pollinators and beneficial organisms.
● Plant different cover crops |
Ensure there are healthy living roots | Living roots protect your soil from erosion and feeds essential organisms in your soil.
● Plant cover crops |
Source: USDA Farmers.gov
Improved soil properties
Cover crops promote soil structure as follows:
- They hold the soil by preventing erosion or blowing away. However, this is often not a problem in raised bed gardens, but it’s a challenge to the ground gardens, especially those in sloppy places.
- Reduce soil compaction. The roots of the cover crops break the soil, which helps in soil friability and water infiltration.
- They form pores in the soil when they decay, which aids in soil aeration and drainage
- Cover crops help in soil aggregation – this increases soil particle size, thus reducing the chances of soil compaction.
Pollinator habitation
Cover crops can provide shelter and food to pollinators and other beneficial organisms. Some of the cover crops loved by pollinators include buckwheat, clover, radish, pea, and sunflowers.
Additionally, some cover crops attract beneficial insects. These insects not only help with pollinating your crops but also helps eliminate harmful pests from your garden. But it doesn’t end in merry for these beneficial insects since pollinators later feed on them.
Breaking pest cycles
Cover crops can help break pest cycles. But how? By removing the host plants and allowing the pests to die. However, success here will depend on the type of pests, crops, and environment.
Additionally, using cover plants to break pests’ cycles often doesn’t yield much in small gardens, even with a crop rotation, due to the small spaces between crops.
Managing weeds
Weeds compete with your crops for nutrients and can even attract pests in your garden. That said, cover crops can help you suppress weeds in the following three ways:
- Cover crops can compete aggressively for nutrients against weeds, therefore overpowering weeds
- Terminated cover crops can function like mulch, thus suppressing weeds and even helping preserve soil moisture. In particular, “oat mulch is perfect, though expensive if you would buy it” – Everson W., Agricultural Officer.
- Some cover crops, especially small grains like winter rye, contain harmful natural chemicals. These chemicals can lead to weed suppression in your garden. However, you will need to note that these chemicals can also harm some crop types.
Sowing Cover Crop Seed
Timing is a crucial factor to consider in cover crop establishment.
Seeding late in the growing season will deny your plants enough time to cover the ground. These plants may even wither in extreme weather since the roots didn’t get enough time to develop.
Also, you don’t have to use a rototiller to prepare your soil to sow the cover crops. You can lightly scratch the soil surface with a hoe or a rake and firmly sow your cover crops.
Terminating Cover Crops
You can terminate cover crops before a growing season to keep them from competing for nutrients with vegetables.
Also, you can terminate them 1 to 2 weeks before planting – before the stems on the cereal grains become too long. You can then incorporate the terminated weeds into the soil.
Cover Crop Challenges
With all the benefits we have seen above of cover crops, these crops may have challenges too. Let’s see some of these possible challenges in detail:
- Terminating cover crops too late can make them grow excessively, making it difficult to incorporate them in tillage. Also, excessively grown cover crops can temporarily tie up soil nitrogen.
- Brassica cover crops can harbor pests and diseases that can affect plants like radishes, bok choi, broccoli, and other vegetable crops.
- Soil improvement is not a one-day thing – it takes time even when you are fully committed to using cover crops
In Summary
As discussed above, cover cropping is essential in gardening and farming. It improves soil properties, provides pollinator habitation, breaks pest cycles, and suppresses weeds.
No wonder Native Americans called the combination of corn, beans, and squash “three sisters.” It’s a sisterhood with benefits! Check this out and more in my next article: Everything You Need To Know About Snap Beans
