What is Soil?

Soil is one of the most important natural resources and is the foundation of farming. The Food and Agriculture Organization estimates that 95% of our food comes from the soil, both directly and indirectly. Farmers know how important it is to take care of the small percentage of soil that can be used for agriculture. In order to take good care of the soil, it is important to understand what is in the soil. Soil is made up of four main components: air (25%), water (25%), minerals (45%), and organic matter (5%).

Mineral Matter

Mineral matter in the soil is mostly comprised of broken rocks. This process takes thousands of years. The type of mineral matter determines the texture of the soil. There are four main texture types when it comes to soil: clay, silt, sand, and loam. Clay has the tiniest particles, having poor water drainage and high compaction abilities. Sand is the opposite of clay and is comprised of large mineral matter particles that do not retain water as well. Silt is made up of medium-sized particles, while loam is a happy mixture of all three textures. Different crops prefer different soil textures, and it is important for farmers to know what type of soil texture they are working with.  

Organic Matter

Organic matter makes up roughly 3-5% of the soil and is comprised of both living and dead organisms. According to the Soil Association, one gram of soil (a quarter of a tablespoon) can contain up to 10 billion organisms. Living organisms, such as worms and bacteria, work together to break down dead organisms, such as leaves and grass. This process creates a humus that increases soil fertility, helps nutrient and water retention, and can even stabilize the pH of the soil.

Air and Water

Air and water work together to fill the remaining volume of the soil, known as pore space. These two components are essential to the health of the microorganisms living in the soil. Seasons of drought or flooding can have a huge impact on the proportions of air and water in the soil. It is important to keep a reasonable balance of the two to ensure crop health. 

To learn more about soil, make sure to check out the newest book from Feeding Minds Press- The Soil in Jackie’s Garden. For additional resources on soil, explore the Soils Ag Mag and the In the Field e-Learning Module!