What Are The Benefits Of Green Manure? (Never Go Without!)


If you are a gardener and you want to improve your soil, then you need to learn about the benefits of green manure.  Once you do, you can make a decision about how to implement this idea in your garden and take the next steps.

So, what are the benefits of green manure?  Green manure adds organic material and nutrients to your soil as it grows and breaks down.  Green manure also prevents weeds from growing, and attracts pollinators (such as bees) to your garden.  Green manure can even be used as feed for animals.

Are you interested in restoring nutrients to your soil naturally without spending lots of money on fertilizer and supplements?  If so, then it’s time to learn a little bit more about green manure and its many benefits.

What Are The Benefits Of Green Manure?

When we talk about green manure, we are referring to the remains of plants.  Green manure often comes from cover crops, such as alfalfa or clover.

alfalfa
Alfalfa is a legume, and serves as a good cover crop for green manure in your garden.

The goal of green manure is to add organic material to soil and to make nutrients more available for other plants.  Green manure is often sown into the soil after the cover crops have had a chance to grow and draw some nutrients from the soil into their plant tissues.

For more information, check out this article on green manure from Wikipedia.

In addition to providing organic material and nutrients to soil, green manure can also help to prevent weeds and soil erosion in your garden.  It can even be used to feed livestock, such as cows or chickens.

Green Manure Adds Organic Material To Soil In Your Garden

One of the big benefits of green manure is the addition of organic material to your garden soil.  Normally, gardeners use compost or manure to add organic material to soil.

For more information, check out my article on how to make compost and my article on where to get manure.

However, these methods involve leaving the compost or manure to decompose in a separate pile, and then moving it to the garden.  You can avoid this extra work by using green manure.

Green manure allows you to “compost in place” by growing cover crops in the same spot where they will eventually be turned into the soil.

peas
Peas are another legume that can be used as a cover crop for green manure in a garden.

The plant matter from the decomposing cover crops will serve the same purpose as grass clippings or leaves in a compost pile: restoring organic material and nutrients to the soil.

Green Manure Adds Nutrients To Soil In Your Garden

Some of the crops used for green manure, such as peas, beans, and alfalfa, are known as legumes.  A legume has roots that contain nitrogen-fixing bacteria (known as Rhizobia).

peanuts
Peanuts are yet another legume that can be used as a cover crop for green manure.

These bacteria take nitrogen from the air, convert it into a form that is usable by plants, and put it into the soil.  For more information, check out this article on legumes from Wikipedia.

Many green manure crops have deep roots.  This means that they can absorb nutrients from deep down in the soil, where shallow-rooted crops could never reach.

Finally, when green manure crops die or are tilled into the soil, the nutrients in the plant are added back to the soil.  Over time, the plant matter will decompose and the nutrients will become available in the soil, in a form that other plants can use.

 The nutrients recovered by deep-rooted cover crops will then become available for shallow-rooted crops that are planted in the same place later.

Green Manure Prevents Weeds From Taking Over Your Garden

Weeds are any plant that you do not want to grow in a specific place.  By that definition, grass would be a weed if it is growing in your garden where you would rather plant tomatoes!

grass
Grass is a weed if it grows where you don’t want it! Cover crops can prevent weeds from taking hold of your garden.

Weeds can grow close to other plants, but they are less likely to take hold if there are already many plants established in a given area.  This is another situation where green manure comes in handy.

If you sow an entire garden with a green manure crop, the weeds will have trouble competing with the established cover crops.

This means that you will see fewer weeds in your garden.   It also means fewer seeds in the soil to sprout into weeds the following year.

Green Manure Prevents Soil Erosion In Your Garden

Soil erosion occurs when the topsoil in an area is taken away by wind or water.  Soil erosion is much more likely to occur in a place where no plants are growing.

Unfortunately, there are times at the end of the growing season (fall and winter) when nothing is growing in your garden.  This also tends to be the time when water can have a devastating effect on your garden by washing away soil nutrients or the soil itself.

soil erosion
Water and wind are two big factors in soil erosion. Planting cover crops can prevent soil erosion in your garden.

When you grow green manure crops in your garden, they will help to hold the topsoil in place.  This prevents soil erosion due to wind or water (from rainstorms or melting snow).

However, green manure is not the only way to prevent soil erosion.  For more information, check out my article on how to prevent soil erosion.

Green Manure Attracts Pollinators To Your Garden

When green manure crops produce flowers, they attract bees and other pollinators to your garden.  This is especially useful if you plant green manure in the early spring.

bee on blueberry flower
Bees are pollinators that are often attracted to the flowers of green manure crops.

Bees that come for the flowers of green manure crops are more likely to find their way to your garden crops.  If you have trouble with pollination (flowers without fruit), then this might be a good way to encourage pollinators to stop by your yard and do their thing!

Green Manure Can Feed Animals

Green manure is typically tilled into the soil and allowed to decompose into the soil.  However, if you have chickens, cows, or other animals to feed, you can use green manure to save money on grain.

chicken wire
Green manure can also be used to feed chickens or other livestock.

Peas, vetch, and clover are all good choices for green manure if you want to use some of the crop as feed for animals.  For more information, check out this article from Penn State University on cover crops for livestock grazing.

Examples Of Green Manure Plants (Cover Crops)

You have many choices when it comes to which cover crops you use as green manure in your garden.  Some of the best choices are legumes, since the bacteria in their roots also help to fix nitrogen from the air into the soil.

Here is a list of some cover crops you can use as green manure.

  • Alfalfa – a legume also known as lucerne, alfalfa has a deep root system.  This makes alfalfa resistant to drought, and allows it to absorb nutrients from deep in the ground.
  • Beans – a legume that grows above ground on vines, beans prefer warm weather to grow.  They are a good source of protein for humans and animals.  You can grow pole beans (tall and narrow) or bush beans (short and wide).
  • Clover – a legume with distinctive 3-section leaves, clover is often used as feed for livestock in addition to being used as a green manure.
  • Peas – an annual legume (they live only one year), peas grow best in cool weather.  They are a good source of protein, making them a good choice for animal feed if you don’t need the whole crop for your garden soil.
  • Vetch – another member of the legume family, vetch is a close relative of peas and lentils.  Once eaten widely by humans, it is often used as a cover crop or as animal feed.

For more information, check out my article on which plants add nitrogen to soil.

When To Sow Green Manure

Sow green manure crops during the fall, after the growing season is finished.  This allows cold-hardy cover crops to grow during the fall and prevent soil erosion during the wet winter months.

At the beginning of spring, you can till the green manure crops directly into the soil to add nutrients and organic material to your garden.

If you decide to sow green manure in the spring, be sure to do it early.  That way, the cover crops will have enough time to grow before you need to till them under the soil to make way for your spring garden crops.

pole beans
Beans are another option for green manure. They grow well in warm weather.

You will also need to wait at least a few weeks before the green manure starts to break down in the soil and release its nutrients.

Regardless of when you sow your green manure, be sure to till it under the soil before it starts to flower.  Otherwise, the cover crop may go to seed, spread out of control, and become a weed itself!

For more information, check out this article on cover crops and green manure from the University of Minnesota Extension.

Conclusion

By now, you know all about the benefits of green manure, and why you might want to use it in your garden.  You also have an idea of some of the cover crops you can use to serve as green manure.

I hope you found this article helpful – if so, please share it with someone who can use the information.  If you have any questions about green manure, please leave a comment below.

For more information, check out this article on green manure from McGill University.

jonathon.david.madore

Hi, I'm Jonathon. I’m the gardening guy (not guru!) who is encouraging everyone to spend more time in the garden. I try to help solve common gardening problems so that you can get the best harvest every year!

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