Plants and soil grass need correct soil conditions to thrive. So, how do earthworms contribute to this? Did you know earthworms are called a farmer or gardener’s best friends? Let us look at five reasons why earthworms are beneficial to the soil.

1. Earthworms increase soil fertility

Plants need nutrients to grow, just like humans need vitamins and a nutritious diet. Earthworms feed on plant debris and other organic matter like animal waste and manure. This diet of the earthworm implies that the digestive system of an earthworm gathers all the organic and inorganic nutrients and minerals from the soil around it, making the cast of earthworms rich in nutrients.

As the earthworms tunnel through the soil, they leave their casts which provide all the gathered nutrients to the soil. Soil Association states, “[Earthworm] casts can contain five times more nitrogen, seven times more phosphorus, and 1000 times more beneficial bacteria than the original soil.” Therefore, we can say that earthworms provide the soil with natural fertilizer that is rich in essential nutrients like nitrogen and phosphorus.

2. Earthworms improve soil drainage

Soils with poor drainage cause the roots of the plants and turfgrass to experience water stress due to waterlogging and puddles. Earthworms improve soil drainage by tunneling through the soil and loosening compact areas. This allows proper circulation of air, water and nutrients in the soil, which improves plant health. 

Also, research on soil biodiversity by the European Commission has shown that soils that have earthworms present in them are able to absorb 90 percent more water than soils without earthworms. Therefore, the presence of earthworms in the soil reduces soil and nutrient loss due to runoff.

3. Earthworms break down thatch

Thatch is a layer of living and dead plant debris (leaves, stems, roots, twigs) that forms between the layers of the grass growing above and the soil below. A thin layer of thatch (less than half an inch) is not harmful to the soil, but once it becomes thicker, it affects the drainage of the soil and prevents water and nutrients from reaching the roots of the plants or grass.

4. Earthworms improve soil structure

Soil structure refers to the way particles of the soil, whether sand, clay, or silt, are grouped together. The casts of earthworms cement or bind the soil particles to create heavier lumps called aggregates. Higher soil aggregate reduces soil erosion, decreases soil and nutrient loss due to runoff, and improves root penetration, moisture retention, and soil drainage.

5. Earthworms encourage the growth of deep root systems

As we have seen, earthworms loosen compacted soil with their tunneling and burrowing actions. Apart from aerating the soil, these activities are also beneficial in encouraging plants and turfgrass to develop a deep root system. When the soil is compacted, the roots of the plants are not able to penetrate deep into the soil, creating shallow root systems. Plants and turfgrass with shallow root systems are weak, unable to withstand harsh conditions and are not tolerant to drought, stress, weeds, pests, and diseases.

6. Earthworms are a source of food for other wildlife

While we have seen that earthworms are highly beneficial to soil health, we also need to understand how they impact the mini-ecosystem of your landscape. Earthworms might be lower on the food chain than most species, but that does not make them any less important. Earthworms are a rich food source for wildlife like birds and frogs, which are helpful in pollinating the landscape.

7. Earthworms help repair damaged or contaminated soil

Soils can get easily contaminated due to environmental and industrial pollutants, and this contamination can damage the soil by degrading its quality. Earthworms help fix this type of damaged soil through a process called bioremediation. Bioremediation is the process by which microorganisms break down contaminants and convert them into non-toxic particles, thus cleaning the soil and improving its quality.