An illustration of soil

What is soil?

So, soil is all around us, but what is it, and what is it made of?

Soil is a mixture of broken rocks and minerals, and decaying organic matter called humus. Humus is dark, soft and rich in nutrients.

In between these bits of weathered rock and humus are spaces for air and water. Every living thing on Earth needs air and water to survive. Having these essential materials - air, water, and organic matter - makes it possible for plants, bacteria, fungi and small animals like earthworms and insects to live in the soil.

How can we study soil?

Scientists who study soil and the orgnisms that live in it are called soil ecologists. Soil study soil in a variety of ways.

With lab experiments, scientists collect soil and bring it back to their labs, where they watch it carefully and make measurements of things like temperature and water content. Lab experiments let scientists watch soil carefully and take careful scientific measurements, but in a non-natural setting.

With long-term monitoring, scientists watch a natural area for a long period of time and record any organisms they find there. Long-term monitoring lets scientists observe organisms in their natural environment over a long period of time, but monitoring can be expensive, and the presence of the scientist disrupts the environment they are trying to study.

With surveying, scientists watch a small part of a natural area in detail, making careful observations and measurements. Then, they move on to a nearby area. Surveying lets scientists get detailed observations, but these measurements are a snapshot in time, and so do not say anything about how the area changes.

We are researching a new study method, sensor networks, in which small measuring tools automatically measure conditions such as temperature and soil moisture, directly in the soil, once every few seconds for several months. These measurements are then uploaded onto computers, from which they can be maintained and searched through. Sensor networks allow for regular measurements over a long period of time, without disturbing the area to be studied. See the About Sensors section for more information on sensor networks.