By George Munene

According to studies on the impact of earthworms on yield, the tiny slimy burrowing worms improve soils, helping boost average crop yields by 25 per cent.

Earthworms improve above-ground biomass and their presence is a key indicator of healthy nutrient-rich soils.

They exponentially increase the availability of microbial life and carbon in soils; determining soil pH; the porosity of soils; availability of nitrogen among other crucial components that determine soil productivity.

Earthworms are crucial in restoring soil organic matter. They are key in forming the most nutritious segment of the soil; topsoil; which in a lot of areas is made of earthworm droppings.

Per the Food and Agriculture Organisation (FAO), 33 per cent of the earth’s soil is degraded, a number that could triple to 90 per cent by 2050. 

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Organic matter is crucial in remedying this as it improves the soil’s water and nutrient holding capacity. 

Unfortunately, unlike chemical fertilisers, organic matter cannot be applied directly to the soil on a commercial scale. It is a complex biological ecosystem that has to be built over time. Earthworms are crucial for this.

On average, every 10-15 years every particle of soil is consumed and extruded by an earthworm. As it goes through its body, microbes within the soil are activated by mucus within the earthworm's body. This increases the availability of nitrogen and carbon within the soils which are primary macronutrients for plants.

They also loosen phosphorous which is easily bound to soil particles and unavailable to most plants. This increases its availability to plants by a factor of hundreds to thousands across different soil profiles. Phosphorous is important for the general health and vigor of all plants.

Further, earthworms can dig up to three meters into the soil improving its drainage and gaseous exchange capacity.

Seeing their impact on crop output how does one boost earthworm numbers in their soils?

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According to Soil Biochemist Jan Willem van Groenigan, although earthworms are critical in reclaiming soils, they require fertile soils to thrive.

“You’ll need to boost your soil’s moisture and food levels. This will require a farmer to properly manage the residue on their farm to provide worms with something to eat. Irrigation is also critical to encourage them to your farm as they are semi-marine creatures that prefer to live in moist environments,” he outlines.

Cover cropping, tillage reduction, and incorporating livestock and other biota (plant and animal life) are important practices in attracting earthworms to your soils and making agricultural systems more sustainable and less leaky to the environment.