blog

Soil: More Than Meets The Eye

February 15, 2010

Be the first to comment

Peel back the layers of this precious resource and discover why soil is so critical to our crops.

By Cole Waggoner, Produce More, Conserve More staff

Close up of a plant growing in soil.

Soil, a complex renewable resource, is a natural element consisting of layers that have formed over time as a result of the physical breakdown of minerals and other organic materials. Its composition is dependent upon three primary elements: mineral matter, organic matter and environmental factors like temperature increases or changes in rainfall.

Mineral Matter

Soil’s framework is provided by minerals, which can include varieties such as oxygen, silicon, aluminum, iron, calcium, sodium potassium and magnesium. These elements, which also make up rocks and the Earth’s crust, are broken down over time by weathering to form soil particles. These mineral surfaces in the soil can hold various amounts of nutrients. According to the College of Tropical Agriculture and Human Resources at the University of Hawaii, knowing the types of minerals that make up the soil in one’s fields “can help predict the degree to which the soil can retain and supply nutrients to plants.”

Organic Matter

Organic matter – a derivative of a once living organism such as a plant or animal – is also embedded in soil, making its way through natural decomposition or through additives like compost or mulch. Organic matter provides additional nutrients which make the soil a rich environment for further plant growth. According to the California Agricultural Water Stewardship Initiative, practices like reduced-till farming and cover cropping can provide great benefits to soil, namely increasing its organic matter content. Increasing the organic matter in soil improves fertility and enhances the structure of the soil by encouraging water infiltration and storage.

The Effects of Varying Climates

While the soil’s composition is dependent upon the materials in the ground, it also varies based on climate. Temperature and moisture affect the weathering and decomposition of minerals. Winds transfer particles and matter to create various combinations of soil. And seasonal conditions like rainfall and temperature alter the soil’s composition, often impacting the production of vegetation.

Although the basic chemical makeup of soil remains somewhat consistent, the specific mineral matter and organic matter, along with environmental factors that affect the soil, are complex. In addition to understanding its composition, there are a number of recommended practices for best managing soil.

Best Practices for Soil Management

Scientists and farmers have established best practices to assess and alter the composition of soil in order to yield the highest crop return. These best practices, identified by the U.S. Environmental Protection Agency, include:

• Using regular soil tests to determine nutrient needs, and applying only the amount of nutrients needed by the crop to be grown.
• Utilizing manure tests to determine nutrient content, and accounting for the nutrient content of manure.
• Implementing conservation tillage and other erosion-control practices to minimize the loss of any phosphorus that is contained in the soil.
• Improving timing of fertilizer application, applying nutrients right before they are needed. For example, corn crops need additional nitrogen after the plants are about three to four weeks old.
• Looking for a low soil test to decide which fields need manure.

It’s critical that farmers and scientists continue to develop and implement best practices to prepare and cultivate soil so that we can sustainably meet the world’s increasing demand for agriculture products.

Start a discussion

Related content