Biogeochemistry is a big word. Biogeochemistry also covers an enormous field of study. It is a systems science – a way of looking at how the Earth’s systems (water, atmosphere, land and living things) interact with each other.

Let’s break the word biogeochemistry down into more familiar syllables:

  • ‘bio’ refers to biology or all of the living things on Earth, which includes plants, animals and microbes.
  • ‘geo’ refers to geology or the Earth’s physical properties, its history and the processes that shape it.
  • ‘chemistry’ refers to atoms and molecules and how they interact with each other.

One important aspect of biogeochemistry is the study of chemical cycles, like nitrogen and phosphorus, and the way they interact with living things and the environment. The transformation and movement of chemicals and nutrients in an ecosystem is called biogeochemical cycling.

Biogeochemistry at work

Nature recycles the minerals and nutrients that plants and animals need for life and growth. When living things die, bacteria break down the organic materials and convert the nutrients in them to forms available for growing plants to use. This cycling of nutrients helps to maintain growth in an ecosystem. Humans can alter biogeochemical cycles when they add fertilisers to farms, change the number of animals per hectare of farmland, harvest crops or restore wetlands.

Nitrogen cycle

Nitrogen cycling is a well known biogeochemical process. All living things require nitrogen for growth, but nitrogen compounds in organic matter often need to be transformed into simpler forms before plants can take them up through their roots. These transformations, or chemical changes in the soil, are part of the nitrogen cycle. The biological component involves different types of bacteria that convert nitrogen into its various forms (ammonium, nitrate, nitrite and so on). Soil properties like soil structure and texture influence nitrogen cycling and the movement of chemicals and nutrients within the ecosystem. All of these processes are interlinked. None of them works in isolation, and each one helps to drive the other.

Phosphorus cycle

Phosphorus is another nutrient necessary for plant growth and also has biological, geological and chemical interactions. The phosphorus cycle begins with the weathering of rocks. Raindrops wash phosphorus and other minerals from the rocks and into the soil. Plants take up these inorganic forms of phosphorus and change them into organic forms. Humans and other animals get the phosphorus they need by eating the plants. Decaying plants, animals and animal wastes return phosphorus to the soil.

Nitrogen and phosphorus are just two examples of biogeochemistry at work. Other biogeochemical cycles include carbon, water, oxygen and energy.

Nature of science

A common stereotype is a lone scientist working in isolation in his/her lab. The process of science is much more often the result of collaboration between scientists. Most areas of research require a wider range of knowledge and expertise than one individual can obtain.

    Published 30 July 2013