Soil regulates nutrients: Nature's recycling system

Where do nutrients go?

At first glance, it may sound like a question a child would ask: "What happens to the nutrients that leave our bodies after we flush the toilet?". Yet the answer takes us to one of the most important processes on Earth.

Every day, we consume foods that provide essential nutrients our bodies need to grow, build and repair tissues, and remain healthy. Our bodies absorb and use some of these nutrients, while the rest is eventually released back into the environment. But what happens to them next?

In nature, nutrients do not simply disappear, instead, they move through continuous cycles among plants, animals, microorganisms, organic matter, water, and soil. Plants absorb nutrients from the soil and use them to grow. Animals obtain these nutrients through their food, and when organisms produce waste or die and decompose, the nutrients can return to the environment, where they become available to support new life.

In a forest or grassland, for example, leaves, roots, and other organic material return to the soil, where they are transformed and recycled. Nutrients are gradually released and taken up again by plants, allowing the cycle to continue. Because most organic material remains within the ecosystem and nutrients are repeatedly recycled, natural ecosystems tend to retain nutrients efficiently, making their nutrient cycles relatively closed compared with many human-managed systems.

Soils are at the heart of this recycling process. They temporarily store nutrients, regulate their release, and provide the conditions needed for organic matter to be transformed. Soil organisms contribute importantly by breaking down organic material and converting nutrients into forms that plants can use. Together, minerals, organic matter, water, air, and living organisms create a system that keeps nutrients moving through ecosystems.

Perhaps a familiar example to you is composting. Food scraps and garden waste contain valuable nutrients that would otherwise be lost. In a compost heap, countless organisms break down this organic matter, gradually transforming it into a dark, nutrient-rich material that can be returned to the soil and support plant growth.

This continuous recycling is one of the reasons healthy soils can support plant growth and ecosystem functioning over long periods of time.

Watch this timelapse video, “Vermicompost – Life in the compost bin”, to get an idea of how long it takes soil organisms to decompose kitchen waste. The video was produced by Wim van Egmond and is only 1 minute long.