The Science

Before you dive into our soil science project, it might be useful to learn more about soils and the nematodes living in them. Feel free to reference this page as you work through the experiment and start thinking of potential research projects to carry out with the data from our community database.

Soil Science

Soil is the combination of minerals, air, water, and organisms - both dead and alive - that make up the Earth’s surface. Most soils originate from the weathering of rock by water, wind, and ice into small sediments that accumulate over time. These same forces, along with the presence of life, can modify the sediments for hundreds, even thousands of years, before they resemble the soils you see outside everyday.

Five primary factors determine how a soil forms: climate, organisms, relief (landscape), parent material, and time (Soil Science Society of America). Soil scientists study these factors to determine both how the soil has matured, and how it will continue to change into the future. Mature soil is the state at which the development and decay of soil is roughly equal, known as dynamic equilibrium. Only once sediments have reached this equilibrium with their environment do they become true soils.

The structure and appearance of a soil can also tell us a lot about its composition and behavior. If you’ve ever picked up a handful of dirt from your backyard, you may notice its color, texture and clumpiness. Soil color indicates its mineral composition. For example, red soils often contain high amounts of iron, whereas black soils have more organic matter. Texture, on the other hand, represents the fraction of sand, silt, and clay within the soil. Sand is the largest soil particle, while clay is the smallest. Soils with lots of sand often drain water very quickly, and soils with a balance of all three generally make for great farmland because they hold water well.

Soil clumps, or “peds”, are made up of sand, silt, clay and other organic matter that has been weakly bound together by environmental changes like freezing, thawing, wetting, and drying. Ped shapes inform scientists of the conditions of soil formation.

Remember that soils are critical for life on Earth! Plants derive nutrients and water from soils, which in turn feeds us and the other animals on the planet. Soil itself is home for countless organisms - just one teaspoon of soil contains more organisms than there are people on the planet. Soil is a crucial part of our ecosystem, and as a citizen-scientist, you have the opportunity to learn more about how the soil functions in your own environment and how you can protect it, and the organisms that thrive in it, from harm.



Nematodes are microscopic worms that are among the most abundant multicellular organisms on Earth. Pick up a handful of soil on any continent, in practically any environment, and you are likely to find thousands of these tiny worms wriggling around within it. They thrive in oceans, deserts, swamps, and almost certainly in your backyard. While some of these nematode species can be parasitic to humans, a majority of them feed on plants, algae, bacteria, fungi and in some cases, other nematodes.

Nematodes are important players in the soil environment. They are responsible for cycling nutrients through the soil by transforming them into forms plants are able to take up. While nematodes are parasitic to plants in many cases - often destroying crops by feeding on plant roots, stems and foliage - they can also protect plants from harmful biological agents.

By feeding on their prey, these nematodes also regulate the growth of bacteria, fungi, plants and other microbes in the soil.

Many factors affect the accumulation of nematodes in the soil. Nematodes may be abundant in soils with high fractions of organic matter, but heavily disturbed soils such as those used for agricultural purposes may negatively influence the nematode population. Scientists have used nematodes to understand soil quality, understand Earth’s biodiversity, and even how animal DNA can be impacted by radiation in space.

As far as appearances go, nematodes are relatively simple. Unlike earthworms, nematodes are unsegmented - meaning they do not have complete circulatory systems and generally cannot be cut into fully functioning pieces. Nematodes are often translucent, leaving their digestive, nervous, excretory and reproductive systems visible underneath a microscope. While most nematodes are microscopic, they can range in size from 0.3mm to over 8 meters depending on the species.