Compost is extremely beneficial to your soil, as most avid gardeners know. Whether worked into the earth or applied as a top dressing, compost can give your plants extra vigor as they grow. Even people who regularly use compost, however, are surprised at just how many ways it can improve their soil with its rich mix of organic matter and living organisms. Below are the top five benefits of compost.
1. Supplying Nutrients
To many people, compost is just another type of fertilizer. They use it simply for its supply of nitrogen, phosphorus, potassium, and other micronutrients. And while compost is a good source of a wide variety of those elements, it is not a concentrated source of specific nutrients as commercial fertilizers are. While that does mean that it’s difficult to use compost as a magic bullet to cure specific deficiencies in your plants, it comes with many upsides. Compost releases its nutrients slowly, over months or even years, whereas commercial fertilizers are typically quickly released and quickly depleted in the soil. Compost also generally features a wide variety of micronutrients, as its composition reflects that of its source materials. This can help prevent plants from developing deficiencies of minor elements like manganese or calcium, which are more likely to arise when relying on an NPK fertilizer.
2. Adding Organic Matter
Most home sites are not chosen for their fertile land, leaving homeowners to struggle with their native soils. While landscape plants can be selected to suit the existing conditions, it’s particularly hard to grow fruits and vegetables in mucky clay or quick-draining sand. Compost can come to the rescue, adding rich organic matter into troublesome soil to create a better growing medium. Not only does compost contain decomposed plants and food scraps, which nourish the soil, it is teeming with fungi, bacteria, and other organisms. These create a dynamic food web in your soil that has far-reaching effects for soil health. Compost is also rich in carbon, and adding it to the soil is a form of carbon sequestration that counters greenhouse gas emissions.
3. Building Soil Structure
Soil is not just one big block of dirt. It is a mix of sand, silt, clay, and organic matter in varying ratios. The spaces between the particles are known as pores, and it is through these pores that air, water, and plant roots move. It is easy to compact the soil, however, and collapse those pores. Compacted soil usually goes hand in hand with new construction, which has seen months of heavy foot and vehicle traffic around the site. Clearing a site of vegetation also usually leads to compaction, as the roots of growing plants are important for establishing and maintaining pore spaces. Not to mention, all the animals and microorganisms the vegetation supported are equally vital for healthy soil structure. Even areas that have been cultivated as lawns can be heavily compacted, the effect of years of foot and mower traffic and a root system that only reaches down a couple inches. Simply mulching with compost can help rebuild soil structure by introducing worms, beetles, fungi, and other organisms that work the soil and create new pores. Tilling the compost into compacted soil can also add diversity to the mix of soil particles, but it runs the risk of destroying any existing organisms in the soil.
4. Retaining Water
One major consequence of improving soil structure is also improving its capacity to receive and store water. When precipitation hits the ground, it can only sink into the soil if there is open pore space to absorb it. Otherwise, it runs off across the surface, eroding topsoil and picking up contaminants along the way. Soil amended with compost is able to capture more of that water and hold it right where plants need it—in the ground. And a nice thick layer of compost as a top-dressing is great for keeping the soil cooler and reduce moisture lost to evaporation.
5. Reducing Waste
In the United States, about 40% of the food that is grown is never eaten. There is more food in landfills than any other single material, where its anaerobic decomposition releases methane, one of the most potent greenhouse gases. That doesn’t even include other organic materials like yard waste, greasy pizza boxes, and shredded paper that are all excellent ingredients for composting. Composting these organic wastes reduces the amount of material send to landfills and sequesters carbon instead of releasing it into the atmosphere. Composting at home cuts out the impact of trucking your waste to a commercial facility, but those commercial facilities also have the ability to compost many materials that are difficult to deal with in a backyard system. Even if you don’t compost at home, participating in a green waste program is an important contribution to reducing waste in landfills.