A Beautiful Mess: Cover Crops

Field planted with cover crops (far right) versus conventionally-farmed field (far left)

By the Tri-State Watershed Alliance

It’s early May in the Midwest, but for most crops, it’s still too early to start planting. How is it, though, that when passing by some brown fields right now, that you see spots of green or even flowers peeking through? Taking a closer look, you might think that the field is full of weeds and that the farmer has just left it to nature. In reality, the farmer has intentionally planted cover crops to improve soil health, control erosion, and suppress weeds in preparation for spring planting. It’s a beautiful mess!

Cover crops work best when a variety of warm and cold season broadleaf plants and grasses are included in the planting mix. Examples include crimson clover, cereal rye, oats, cow peas, Austrian winter peas, Daikon radish, vetch, turnip, rapeseed, and buckwheat, and ideally, are planted after early-harvested crops such as wheat, sweet corn, and seed corn. They can be seeded with ground equipment like drills or broadcast equipment or aerially applied.

Cover crops improve soil health by providing nitrogen for future crops, taking up excess nitrogen, and reducing the potential for groundwater leaching. In this regard, there may be less need to apply purchased nitrogen fertilizer for the subsequent crop translating to reduced nitrogen losses to the environment and lower production costs.

Cover crops also aid in weed suppression by shading and interfering with weed germination and establishment. Cereal rye has even been shown to produce a weed suppressing substance. Additionally, the roots of cover crops help to reduce soil compaction which then allows for increased

Soil amended by cover crops

water percolation and retention. Cover crops are also useful in controlling erosion due to rainfall, snowmelt, and wind by shielding the soil surface from impact and reducing runoff that could be harmful to nearby rivers and streams.

Some cover crops, of course, will be winter-killed, while some will return in the spring. In choosing to plant cover crops, take into consideration that fields with early season cover crop growth may be more vulnerable to soil insects such as cut worm, army worms, and slugs requiring control procedures before planting a new crop. Some cover crops require early termination to prevent soil fertility issues. Terminating cover crops may be attempted by mechanical means, although reduced tillage systems often don’t provide complete control. Chemicals used in the termination process include 2, 4-D ester and glyphosate the application of which must be well-timed to the correct growth stage of the cover crop.

Discussing the various types of cover crops with agriculture students

In terms of the economics of planting cover crops, it all depends on many variables. To aid in decision making, the Natural Resources Conservation Service has developed a budgeting tool to help farmers assess the profitability and affordability of adopting the practice.

As you can see, there is a method to the farmer’s madness in planting cover crops. It’s an easy and environmentally-friendly way to improve soil health, control erosion, and suppress weeds.

Resources for information on the benefits of cover crops and termination procedures are available at:

Natural Resources Conservation Service

Michigan State University Extension
http://msue.anr.msu.edu/topic/cover_crops/getting_started_and_management, http://msue.anr.msu.edu/topic/cover_crops/getting_started_and_management/termination

The Ohio State University Extension

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