One natural way to manage weeds in your garden and improve soil structure is to use cover crops. This method dates as far back as ancient Greek and Roman times [1].
Cover crops (green manures) are fast-growing plants grown with the aim of incorporating them into the soil while still green. They also help prevent soil erosion, all while providing grazing and fodder for farm animals.
Main Benefits of Cover Crops
Soil improvement is the main aim of planting cover crops for gardens.
- Weed suppression. These plants can block sunlight, smothering weeds.
- Legume cover crops recycle and add nitrogen to the soil.
- Aeration is a further benefit, preventing the soil from compacting and allowing other plants to thrive.
- Conserve soil moisture. Cover crops trap water, allowing it to filter deep into the soil.
- They also hold the soil in place, thereby preventing soil erosion.
- Green manures add nutrients by increasing soil organic matter.
- If properly managed, garden cover crops can also provide mulching benefits.
- Living mulches also serve as great ground covers.
Cover Crop Examples
Cover crops fall into four classes: grasses, legumes, brassicas, and non-legumes broadleaves.
Grasses
These are not only useful but are also very attractive plants. For the practical gardener, grasses are annual cereals useful in holding the soil in place, thus reducing soil erosion.
They also work for suppressing weeds and accumulating soil nitrogen. Additionally, the residue left after cutting provides a nutrient-rich mulch that helps retain soil moisture.
This category includes rye, corn, oats, wheat, and barley.
Legumes
Legumes are good cover crops grown mostly for their ability to enrich the soil with nitrogen. They fix nitrogen from the atmosphere and supply it to the soil.
Additionally, living plants add organic matter, attract pollinators and beneficial predatory insects, and help prevent erosion of the soil.
Examples include white clover, hairy vetch, field peas, sweet clover, and alfalfa.
Brassicas
This category includes the eye-catching yellow fields of rapeseed and mustards. Generally, these cover plants are cultivated to prevent fall erosion and help in pest management.
Radish and turnips are other examples. These both have many useful properties. They help suppress the growth of weeds and may also help in the control of fungal issues.
Non-Legume Broadleaves
These crops make green manure, recycle existing soil nitrogen, and bind the soil together. However, they cannot fix nitrogen from the atmosphere.
Non-legume cover crops include flax and spinach.
Summer Cover Crops
Crop monitoring will help determine which cover plant or group suits the specific needs and conditions for vegetable gardens.
In general, those most suitable for summer growth are buckwheat, cowpeas, sudangrass, and wheat.
Winter Cover Crops
Winter conditions can badly affect some crops like canola. Others, however, like crimson clover, winter rye, hairy vetch, and Austrian peas are suitable. Moreover, clover is an edible weed.
You can also grow winter wheat in any suitable environment. After producing in early spring, they can be killed off and tilled in to enrich the soil for the summer crops.
Winter-Killing
Experienced gardeners will know exactly the right moment when the growing benefits of these crops have reached their peak and are going to seed. This is the time to kill off the plants.
Crops that naturally die of the cold form a nutritious surface mulch that protects the ground from erosion. Moreover, those that are winter-killed by other means can leave the ground free for early spring.
Crop residue, depending on the type, may be tilled in to enrich the soil. Mowing is the most common method of crop kill. However, a labor-saving useful way is to allow animals to graze.
Planting for Grazing
Sowing cover crops for grazing farm animals has many benefits. It is primarily a cost-effective way of feeding livestock.
In turn, grazing animals help reduce soil compaction by their movements. Moreover, dung helps increase soil organic matter.
Cover plants for grazing include cereal grains like wheat, oats, barley, and millet. Additionally, there are legumes such as alfalfa, peas, beans, and clovers.
Specific Uses of Cover Crops
Establishing objectives when planting (buy seeds here) can help you select the right plants.
- Nitrogen fixation. Legumes such as cowpeas, velvet beans, hairy vetch, and clovers. Cabbage and other brassicas require a lot of nitrogen so planting legumes first is beneficial. Tomatoes also absorb a lot of nutrients and benefit from the prior planting of nitrogen fixers.
- Moisture improvement and retention. Crimson and white clovers, winter wheat, rye, and rapeseed.
- Reducing compaction of the soil. Turnips, radishes, canola, and sunflowers.
- Weed cover and short-term cropping. Oats and red clover or quick-growers like buckwheat.
- Residue cycling. The brassicas are best for this, e.g. radishes, turnips, rapeseed, and mustards. Most brassicas are winter-killed, providing nitrogen-rich residue. Tender plants like buckwheat will rot down. They are then absorbed into the soil speedily but others like carbon-producing sorghum take longer.
- Long-period cropping. Mixes of small cereal grains like barley or rye with nitrogen-fixing legumes such as vetch, clovers, or cowpeas.
Home Gardening
This method practiced on a small scale need not be daunting. After getting your seeds, start with something like buckwheat.
Easily sown and fast-growing, buckwheat thrives well in moist and cool conditions. It also rapidly smothers weeds and the small white flowers attract beneficial predatory insects and pollinators like bees and butterflies.
Easily killed and incorporated into the soil, buckwheat leaves valuable nutrients for soil enrichment. For the home garden, you can also experiment with annual ryegrass.
Takeaway
The use of cover crops has a central place in agriculture. Sown in rotation throughout the year, these crops are grown to repair and/or enrich soils. They do so by improving the structure and influencing the amount of nitrogen and other nutrients.
Moreover, they are effective in increasing and retaining moisture, suppressing weeds naturally, and preventing soil erosion. Some are also great at attracting pollinators and beneficial insects.
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