James Pinsky: Use a cover crop after harvest

James Pinsky

I know a lot of friendly folks. None of them leave their front doors wide open while they’re away. I know I don’t.

Houses are pretty easy to secure. We close and lock our windows, doors and even our garages. Makes perfect sense, doesn’t it?

After all, our homes are sacred and what we have in them, we tend to want to keep. So, why do we leave our land wide open after harvest?

Wait. What?

Why do we leave our soil, which we have worked all season long to make sure it is rich with nutrients, barren after we pull our main crops? Once we harvest our main crops, if we don’t want our soil to lose moisture, organic matter and nutrients, or gain weeds, then we ought to strongly consider using a cover crop. Like a front door on our house, cover crops can serve as a strong barrier to keep our soil in place and keep anything we don’t want in it, out.

What exactly is a cover crop? According to the Natural Resources Conservation Service, a long-time partner with all of Virginia’s Soil and Water Conservation Districts, a cover crop is defined as any living ground cover that is planted into or after a cash crop and then commonly destroyed before the next crop is planted. As a best management practice, cover crops, at the very least, help control runoff and soil erosion. According to the Natural Resources Conservation Service, cover crops have many advantages.

The protective canopy formed by a cover crop reduces the impact of rain drops on the soil surface, thereby decreasing the breakdown of soil aggregates. This greatly reduces soil erosion and runoff, and increases infiltration. Decreased soil loss and runoff translates to reduced transport of valuable nutrients, pesticides, herbicides and harmful pathogens associated with manure from farmland that degrade the quality of streams, rivers and water bodies and pose a threat to human health.

A cover crop slows the velocity of runoff from rainfall and snow melt, reducing soil loss due to sheet and rill erosion.

Over time, a cover crop regimen will increase soil organic matter, leading to improvements in soil structure and stability, and increased moisture and nutrient holding capacity for plant growth. These properties will reduce runoff through improved infiltration (movement of water through the soil surface) and percolation (movement of water through the soil profile).

A cover crop will increase soil quality by improving the biological, chemical and physical soil properties.

As a “trap crop,” a cover crop will store nutrients from manure, mineralized organic nitrogen or underutilized fertilizer until the following years’ crop can utilize them, reducing nutrient runoff and leaching.

When a cover crop is managed for its contribution to soil nitrogen, the application of a nitrogen fertilizer for the subsequent crop may be less, thereby lowering costs of production, reducing nitrogen losses to the environment and reducing the use of purchased nitrogen fertilizer that is produced using fossil fuels.

Cover crops will reduce or mitigate soil compaction. Deep tap roots of some cover crops grown in the fall and spring when compacted layers are relatively soft and can penetrate these layers.

A cover crop provides a natural means of suppressing soil diseases and pests. It can also serve as a mulch or cover to assist in suppressing weed growth.

A cover crop can provide high-quality material for grazing livestock or haying and can provide food and habitat for wildlife, beneficial insects and pollinators.

The Lord Fairfax Soil and Water Conservation District has a cost-share program for cover crops. To learn more about this program and other best management practices consult the conservation experts here at Lord Fairfax Soil and Water Conservation District or our federal partners, the Natural Resources Conservation Service.

James Pinsky is the education and information coordinator for the Lord Fairfax Soil and Water Conservation District.  Contact him at 540.465.2424, ext. 104, or james.pinsky@lfswcd.org.