Did you know that when applied to soil, compost helps retain water so well that irrigation can be reduced or even eliminated? This applies to both large farms and your own home garden.

Composting has environmental, economic and social benefits on a large and small scale. Some are direct and immediate, others longer term. Learn about the full spectrum of composting benefits for soil, ecosystems, communities, waterways, and home gardens.

Soil benefits of using compost

The benefits of compost for soil quality are many, as you will read below. The fact that compost can improve soil is especially important as soil quality is declining in the US and many agricultural areas that grow food. One of the easiest and easiest ways to improve the soil, whether in city parks or in your own vegetable patch, is by adding compost.

Compost feeds the soil food network

When compost breaks down, it supplies vital nutrients to the soil. Compost contains the three most important nutrients plants need: nitrogen, phosphorus, and potassium. Compost not only feeds the plants that grow in this soil, it also uses existing materials, many of which are already free or are by-products of the food system. Compost also increases the number and diversity of beneficial bacteria and fungi in the soil, which allows plants to grow.

Reduces the need for chemical fertilizers

Chemical fertilizers have a variety of environmental impacts that go beyond providing nutrients to the soil in which they are applied. First, they need to be manufactured, shipped and used, which costs time and money – as do carbon emissions as many fertilizers are made from non-renewable petroleum products. Extracting these fossil fuels from the earth has a huge carbon footprint. Then energy is needed to process them into fertilizers and get them where they are needed.

Not only do the chemical fertilizers incur these various costs, but they also damage the waterways they flow into after being used for crops. The excess nutrients flow into the waterways, causing regular algal blooms that eventually die. During their decomposition, oxygen is lost from the water. These “dead zones” then kill fish or force them to move. Compost can prevent these carbon emissions and not only relieve the waterways, but even improve them (see below).

Compost increases soil moisture

The use of compost can increase the soil’s ability to retain water so much that it reduces the need for irrigation. This is especially important for farmers who live in areas that are drying up or suffering from more drought.

Of course, how much more water a soil mixed with compost can hold depends on the compost, as well as the soil conditions and the ambient air temperature and moisture content. However, studies have shown that for every 1% of organic matter content, the soil “can hold 16,500 gallons of plant-available water per acre of soil up to a foot deep,” according to the Michigan State University extension. That doubles if you can get the organic matter up to 2% (it’s difficult to get it too high as the organic matter breaks down).

Other studies have shown that compost reduces soil crust formation (so water can get into the soil more easily) and spreads the water laterally where it hits the soil, which means it evaporates less quickly. All of these things help the water get to the plant roots more effectively.

Rows of compost heaps in Pirkanmaa, Finland.

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It prevents soil erosion

From highway embankments in Louisiana to sloping and cultivated fields in Illinois, adding compost to soils has been found to reduce soil erosion and prevent soil runoff, protecting streams and other waterways from cloudiness (muddy water) that harms fish can aquatic invertebrates. This is because composted soils are better at retaining water.

Compost benefits for plants

Unsurprisingly, the plants growing in this soil also reap the benefits of improving soil health and water availability through compost.

It supports plant growth

Plants that grow in soils that have been modified with compost produce significantly more biomass. That means 50% or more grass in grasslands where cattle graze, or more vegetables. In an Italian study, compost increased lettuce and kohlrabi growth by 24% and 32%, respectively.

Composting improves plant nutrition

The quality of the products grown in compost also tends to be higher. Quinoa plants in India improved the antioxidant defense machinery, which resulted in a significant increase in the plants’ ability to draw nutrients from the soil. In a long-term study in China, wheat fields had significantly higher yields compared to a control field with uncomposted soil.

It can lower the death rate of plants

Not only will more plants grow on composted soil, but they will also grow stronger, which will reduce the diseases plants can get. Since crop failures are costly for both home gardeners and farmers, compost is another way to save money when growing food or other crops.

Environmental benefits of composting

Of course, improving the soil and growing crops with fewer chemicals are both environmental benefits, but there are more direct ways that composting can help the larger environment by reducing greenhouse gases and waste.

Composting reduces waste

This is obvious – if food waste and garden litter don’t end up in the landfill, it reduces a city’s space (and fees) for garbage disposal. What is surprising, however, is how much waste can be diverted through composting and how high the savings are.

According to the EPA, leftover food and garden waste make up more than 30% of a typical waste stream. Yes, that’s almost 1/3 of our garbage that can not only be kept out of the landfill, save space and save money for communities and cities, but can also be turned into useful material that can replace or reduce expensive chemical fertilizers used by Used by local authorities, or give home gardens free food.

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That saves money

Landfill sites are expensive and prices only continue to rise because landfill spaces are getting smaller and smaller. In 1990 there were more than 6,000 landfills in the United States; that number fell to 1,269 in 2018.

In 2020, the average cost of landfilling a ton of solid waste was nearly $ 54 per ton (in California, Oregon, and Washington, that price was significantly higher at $ 70 or more per ton). If the US dumps more than 250 million tons of waste in landfills every year, those costs add up – now imagine if you could cut it by 1/3. That’s potentially billions of dollars saved from composting.

Composting reduces methane emissions in landfills

When organic matter breaks down in a low-oxygen environment such as a landfill (piles of trash don’t let enough air into the lower layers) it will break down anaerobically. This creates methane, a greenhouse gas 28-34 times more potent than the same amount of carbon dioxide. And landfills produce a lot of methane (they’re the third largest source of gas in the US): the volume of a landfill is 45% to 60% methane and 40% to 60% carbon dioxide.

One way to reduce the amount of methane landfill produced is to compost those materials (such as organics) that produce methane when they decompose anaerobically

It can bind more carbon from the air

A 2018 report found that just 1/4 inch compost added to several different types of soil in California “resulted in a detectable and significant net increase in soil carbon storage” compared to untreated soils. About 900 additional pounds of carbon per year and acre was captured in soils with added compost.

Interestingly, when modeled over time, this effect lasted for 30 years, with the greatest sequestration potential being around 15 years after just one compost application.

The scientist behind the report, Dr. Whendee Silver, calculated that spreading 1/2-inch compost over half of California’s grasslands could remove carbon from the air at such a significant rate that it would offset greenhouse gas emissions for the entire state of California for one year.

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Agricultural waste is used in composting

When most crops are grown and processed, there is often waste in the form of additional plant materials that are not needed. A study in India found that around half of this waste was used by locals as roofing material for animal feed, fuel for heating, or packaging material, but the rest is disposed of by incineration, which is a cheap and easy way to get rid of the extra material and an easy way to get rid of the extra material Prepare the field for the next planting.

However, burning leads to air pollution and negative effects on respiratory health, and also contributes little to the soil that was depleted when the crops were grown. Using this material as compost prevents both the negative effects of combustion and the use of a free source of nutrients back into the soil.

Composting can help with rainwater management and quality

As we learned in the soil section above, compost holds more moisture in the soil, which results in less runoff. Compost can be used in place of other materials like plastic sheeting in places with disturbed soils like construction sites, according to the EPA.

Composting also has social benefits

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Whether you are composting in your home garden or complimenting the weekly pickup in your town, once you start composting you will realize the amount of food wasted and the cost of it. In some cases, this awareness can help households reduce food waste in general.

When this former garbage is collected separately, its value is highlighted and the idea of ​​compost as “black gold” gains new meaning. Children can also learn valuable concepts in environmental science, agriculture, chemistry, and the carbon cycle by learning how to compost and engaging in it themselves. It is simple enough for even young children to understand, and complexity can increase as the children grow.