Rows of compost ready for sale.

23 Benefits of Compost Backed by Science

“The nation that destroys its soil destroys itself.”

Franklin D. Roosevelt

There was a time when scientists thought agriculture was simple. 

You added fertilisers, plants used the fertilisers to grow. 

But the more we study the soil, and the environment, the more we learn about the interconnection between soil, plants and food 

It’s a fascinating, complicated subject. And while we still have a lot to learn, it’s clear that the benefits of compost are huge and interwoven.

In this article you’ll find benefits of composting and compost for the small scale gardener, for large scale agriculture and for the world. 

Contents

Benefits of compost for your soil

Infographic demonstrating benefits of compost for soil.

To understand this section, it’s worth exploring soil structure and aggregation first. 

The same organisms that break down organic matter in compost release a sticky, glue like substance. 

This helps bind individual particles of clay, soil and sand group together into larger particles called aggregates, leading to a soil which is dark and crumbly. 

This process is called aggregation. 

Studies show that compost can have a major impact on aggregation. For example, one study found that the application of composted organic material can increase aggregate formation by 45%

Aggregation leads to improved soil structure, creating a dark, crumbly soil. It also links to many of the benefits compost creates for the gardener. 

Learn more about compost, soil structure and aggregation.

1. Moisture retention

A sandy soil will let water drain away too quickly. 

Through the process of aggregation, adding compost leads to larger soil particles that can hold more moisture.  

2. Improved drainage

Compost can also help improve drainage. That may seem strange when it can also hold more moisture, but it’s also down to the aggregation process. 

As particles in the soil bind together, they open up more space between the particles. These spaces, called pores, carry water down into the soil. That’s why compost rich soils often have less puddles than other ground after heavy downpours. 

3. Improved Aeration

Those pores don’t just drain water – they also hold air pockets. What’s more soil enriched with compost encourages microbes and worms. The activity of these creatures create further air pockets in the ground.  

According to the Rodale Book of Compost, the benefits of aerated soil include: 

  • Preventing the loss of organic material
  • The maintenance of nitrogen content
  • Improved uptake of nutrients by plants

4. More nutrients for your plants

Adding compost to your ground increases the availability of nutrients to the soil. It does this in several ways. 

  1. As the compost continues to break down, it slowly releases nutrients such as nitrogen, phosphorus and potassium into the ground. 
  2. It increases the ability of the soil to hold on to nutrients (the cation exchange capacity).
  3. Compost produces food for microbes, which provide food for other organisms, both of which make nutrients available to plants.

5. Delivers nutrients at the right time

In contrast to many artificial fertilisers, compost delivers the most nutrients when the plants need it most. 

In the winter, when the weather is cold and there is less light, fewer nutrients are delivered. 

As the weather warms up and there is more light, plants grow more and require more nutrients. Soil which has received regular top-ups of compost and more micro-organisms, delivers more nutrients at this time. This is because the microbes and organisms that release the nutrients are more active. 

6. Encourage Mycorrhizal Fungi

Mycorrhizal Fungi is a fascinating organism that forms a living, interconnected, mutually beneficial relationship with the roots of plants and trees. 

It carries huge benefits for gardeners, which include:

  • Increasing the ability of plants to withstand drought, temperature changes
  • Protection against soil pathogens
  • Improved mineral nutrient uptake
  • Transfering nitrogen from plants with plenty of nitrogen to plants that don’t have enough. 

Martin Crawford, author of Creating a Forest Garden, believes that plants with Mycorrhizae can grow as much as 4.5 times as much as plants without Mycorrhizae. 

Adding organic matter such as compost encourages Mycorrhizae to flourish.  To maximise benefits, don’t dig the compost into the ground, as digging can easily destroy the fragile fungus. Instead, spread the compost on the top of the surface and plant straight into it. 

7. Stabilises PH Levels

Compost buffers PH levels

It does this in two ways. 

Compost absorbs the ions which would otherwise be washed away, holding them in place. 

It also encourages earthworms, which makes acid soil less acid and alkaline soil less alkaline. 

8. Kills pathogens and weed seeds

The process of hot composting can kill both pathogens and weed seeds in compost. 

The cleaning process doesn’t stop there either. 

Some experiments suggest that even at lower temperatures, micro-organisms can be highly effective in removing diseases such as E.coli.

(An interesting experiment is listed here – I haven’t live linked as the website does not have a security certificate: http://www.transformcompostsystems.com/blog/2017/11/02/killing-potential-pathogens-in-compost-cold-and-calculated/)

9. Fewer pests and diseases

Good soils leads to healthy plants, which have an increased resistance to diseases and insect damage. 

The use of organic material to boost the resilience of plants is not new. After all, before we had access to pesticides, we had to use other methods of discouraging pests. 

And wise farmers, such as US President Thomas Jefferson, knew that adding compost and manure lead to strong plants that could risk the dual attacks of insects and disease. 

Compost doesn’t just help by creating stronger plants –  compost can directly suppress disease, and different compost formulations can help with different diseases.

Benefits of compost for the economy

Infographic showing the benefits of compost for the environment.

10. Erosion

As FH King noted in his book Farmers of Forty Centuries, societies in Asia farmed for thousand years of years without destroying their top soils. That may well have been due to their use of compost and humanure. 

Yet the WWF states that in the last century and a half, half of all topsoil in the world has been lost, while the United Nations estimates that fertile soil is being lost at the rate of 24 billions tonnes of soil a year. 

The impact of erosion is devastating. 

It includes:

  • Flooding, and its impact on our lives, economy and property
  • Loss of fertility. This threatens future crops and has already lead to the loss of 33.7 billion tons of global food production. That costs the global economy an estimated eight billion dollars a year
  • Damage to the environment via soil entering freshwater rivers, streams and lakes. This soil often contains pesticides which increases damage to water eco-systems. 
  • Fewer plants and less carbon holding soil, leading to increased carbon emissions and accelerated global warming.

Agriculture and land management is a major cause of erosion. But, as FH King noted, the use of compost (or, in his case, humanure) can prevent erosion. 

Modern studies back this up, finding that the addition of compost can reduce soil erosion by up to 99% when compared to other methods. 

12. Reduce pollutants in stormwater

Stormwater can carry man-made chemicals, salts and other pollutants into our streams, rivers, lakes and seas. 

As we’ve seen, compost can increase the ability of soil to absorb water. 

Studies show it can also act as a filter for stormwater and reduce the leaching of pesticides, herbicides and other harmful substances from fields. 

13. Cleaning polluted soils

Compost has an amazing ability to clean up polluted soils in a process called bioremediation. 

One successful example occurred in Palmerton, Pennsylvania, where an area of four square miles was heavily contaminated with heavy metals. 

US scientists were able to clean the area using a combination of grass, lime fertiliser and compost. 

According to the US Environmental Protection Agency, compost is able to help with the cleaning of: 

  • chlorinated and non chlorinated hydrocarbons
  • wood-preserving chemicals
  • Solvents
  • heavy metals
  • pesticides
  • petroleum products
  • explosives

14. Reduces Emissions

Compost can reduce emissions in several ways. These include:

By replacing synthetic fertilisers

Synthetic fertilisers may lead to the loss of nitrogen from the ground. This eventually enters the air in the form of nitrous oxide (N2O). N20 is 300 times more effective at trapping heat in the climate than carbon dioxide. 

By reducing the amount of landfill. 

The Global Methane Initative estimates that landfill causes the release of 1077 million metric tonnes of methane. Methane traps 21 times more heat in the atmosphere than carbon dioxide. The US EPA estimates that around just under a third of landfill waste is food waste – waste that can be turned into compost. 

One key here is the gases that are produced. Aerobic (with air) composting does produce CO2, but most sources state methane releases are either non-existent or lower than anaerobic composting. There are also low-cost ways to reduce CO2 emissions when commercial compost is produced.

15. Carbon sequestering

Land farmed with compost and cover crops can increase carbon in the soil by 0.07% a year.

To put that into context, the 4 Per Thousand campaign estimates we need to increase carbon in the soil by 0.04% to significantly reduce the CO2 concentration in the atmosphere.

Benefits of compost for the environment

Infographic demonstrating benefit of compost for jobs.

16. Changing waste into product

Each year 1.8 billion tonnes of food is lost or wasted.

That’s a third of the world’s food supply. 

Much of that can be turned into compost that can be sold and traded. 

The use of the compost leads to more fertile and resilient farmland, which would provide a better return on investment for farmers and agricultural investors. 

The gain doesn’t just lie in the finished product as well. 

Compost produces a lot of heat. That heat can be used to warm houses, greenhouses and polytunnels, and even to produce clean electricity. 

If we’re brave enough to use humanure, the opportunity becomes even bigger. The world produces 640 billion lbs of excrement and 3.8 billion pounds or urine. It spends billions on processing and disposing of that waste. 

It’s a massive opportunity to turn something that costs a lot of money into something that can make a lot of money. 

17. Reduce landfill costs: 

Landfills take up space and resources, and in many countries these are now charged to business and local government. 

As we saw earlier, 30% of that land fill is food waste

Much of those costs are passed on to businesses and consumers – but composting can help reduce these costs. For example, one college in Vermont was able to save USD100,000 by composting 90% of its food waste. 

18. Lower the cost of food

In recent decades the world has been suffering from increasing food prices or ‘agflation’.

The consequences have been devastating, especially on the poorest in this world. They include: 

  • Social unrest and riots
  • Increased inflation
  • Malnutrition and disease
  • An increase in the death rate – what the World Bank calls a Silent Tsunami 

Compost can help by improving our soil, reducing the need for fertilisers/pesticides and reducing soil erosion.

Benefits of compost for your pocket

19. Lowers the cost of gardening 

Here’s what happens when you make compost. 

You start with something that is not only worthless, but costs money to take away. Then you turn it into something that has value. (After all, it’s not for nothing that it is called Black Gold!)

What’s more, when you make your own compost, you can have compost you can have confidence in. You know you haven’t sprayed your garden with the herbicides that have found themselves in some composts

If you have a large garden, you could easily produce good compost that would costs hundreds of pounds in your local gardening store. 

All the great compost means you can grow more food for your family, as well, saving you even more money every year. 

Benefits of compost for health

An eldery woman planting with compost.

20. Healthy soil, healthy food

The ideal that the health of our soil is connected to our own health is not new. In fact, Hippocrates include an examination of the soil as part of his medical evaluation checklist in 400 BC. 

Hippocrates’ belief that soil is linked to human health is increasingly backed up by science. 

Plants take up both nutrients and micronutrients from the soil. Our bodies then use many of the same nutrients and micronutrients. 

Quite simply, plants grown in nutrient-rich soil are better for us than those grown in poor soils. Indeed, nutrient poor soil may be the reason why more than 2 billion people in the world are suffering from micro-nutrient deficiency

21. Fewer pesticides, fewer diseases

Research is starting to suggest links between pesticides and health conditions, including serious disease, including:

  • skin and eye irritation
  • Nausea
  • Cancer
  • asthma
  • Diabetes

Compost grown plants require fewer pesticides, and have the potential to reduce disease. 

22. Compost may help with mental health

Mycobacterium vaccae is a fascinating bacteria that is found in both compost and healthy soil. 

When scientists injected Mycobacterium vaccae into mice, it had a similar effect to antidepressants.

It also lowers inflammation in the brain and appears to help prevent post-traumatic stress disorder. 

Scientists are now studying the bacteria to see how it can help create medicine. 

23. Cleaner Water, Fewer Diseases

Dirty and polluted water has a huge impact on world health. 

TheWorldCounts estimates it causes 3,575,000 deaths a year

2.2 million of these are children. 

Solving the problem of dirty water will need an integrated approach which addresses poverty, sanitation and other issues. Compost, with its ability to filter water, reduce the need for fertilisers and reduce storm runoff, could be one part of this solution.

In summary

We’re still finding out more about the amazing abilities of compost to contribute to the world. 

One particular exciting area is specific formulations of compost. It seems likely that in the future compost will be manufactured specifically for different purposes, such as treating different soil diseases. 

While we are still learning, it’s already crystal clear that compost offers a huge host of benefits, whether it’s used at scale or in the garden. 

Making compost is also fun, and offers a great sense of achievement to turn rubbish into black gold in your garden or kitchen. I hope you enjoy the process as much as I do!

Infographic elements above are from the Institute for Local Self-Reliance (ILRS.org), and are reprinted here with permission. You can view the full infographic here.