How Cover Crops Work

Cover Crops can be used to improve soil quality, reduce weed competition, increase air and water infiltration, and even as a forage for livestock and wildlife. But how do plants achieve this?

At their core, cover crops work by keeping more of the soil covered, rooted, and biologically active during times when a field might otherwise be bare. This closely follows the USDA Natural Resources Conservation Service’s soil health principles: maximize living roots, minimize disturbance, maximize soil cover, and maximize biodiversity.

Keeping Living Roots in the Soil

One of the most important things a cover crop does happens below the surface. Living roots continuously interact with the soil around them, releasing carbon-rich compounds that feed fungi, bacteria, and other soil organisms.

That biological activity helps cycle nutrients, build soil aggregates, and create a more functional soil structure. Different cover crop species also develop different root systems. Fibrous-rooted grasses can hold soil and explore the upper soil profile, while species with deeper taproots can penetrate farther into the soil and help capture nutrients that might otherwise be out of reach.

The result is more than simply having another plant in the field. Cover crops help keep the soil ecosystem functioning for a longer portion of the year.

Protecting the Soil Surface

Bare soil is vulnerable to wind, heavy rain, temperature extremes, and erosion. A growing cover crop and even the residue it leaves behind creates a protective layer for your soil. The plant leaves and residue help absorb the impact of weather events, reducing soil particle detachment and crusting, while the roots help hold soil in place.

Essentially, cover crops act like a shield: keeping the valuable topsoil, nutrients, and organic matter where they belong.

Building Diversity Above and Below Ground

A field planted to the same crop year after year provides a relatively narrow range of roots and food sources for soil microbiology. Incorporating cover crops introduces additional plant species into the rotation and increases the diversity of the whole system.

That kind of diversity can be especially valuable when cover crop mixes include plants with different growth habits and functions. Grasses, legumes, brassicas, and broadleaf species each interact with the soil differently. Together, they can occupy different rooting depths, capture different nutrients, produce varying types of residue, and support a wider range of soil organisms.

Greater diversity does not automatically mean that every mix needs a long list of species. The most useful mix is one selected for a specific field, planting window, and management goal.

Managing Water More Effectively

Whether you are irrigating or relying on rainfall, cover crops influence what happens to water once it reaches the soil. Root growth and increased biological activity can help improve soil aggregation, allowing moisture to move into the soil profile rather than pooling up or running across the soil surface. Over time, soils with better structure will be able to absorb and store more water for later use. 

Living cover crops do use water while they are growing, so species selection and termination timing are important in dry environments. When managed properly, cover crops can help create a soil system that captures rainfall more efficiently and makes better use of available moisture over time.

Creating a More Resilient Cropping System

Over time, these interactions can help build a living soil that is better able to handle changing weather conditions and make efficient use of its resources.

This does not mean cover crops are a one-step solution. They may require additional management, and establishment, seed, termination, labor, and equipment that can all add costs. Research has shown that the greatest benefits come when cover crops are incorporated thoughtfully into the entire cropping system rather than treated as an isolated practice.

The goal is not simply to grow another crop between harvest and planting. It is to use living plants to protect the soil, build biological activity, manage water more effectively, and create a system that remains productive for the long term.

Last Updated: 08/27/2026