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There Are Short-Term Impacts of Cover Crops

There Are Short-Term Impacts of Cover Crops
Red clover cover supplies about 150 pounds of nitrogen per acre to the following corn crop.

By Jamie Patton

I will admit it. I am uncool. I don’t know the reality TV stars and I can’t read text message lingo without the help of Google. I probably should work on improving my trendiness, but let’s be honest -- I just don’t care. 

However, as a soil geek, I do know the new "it" in the agronomy world. And I’m guessing, unless you haven’t picked up a farm publication in the last five years, you’ve heard of them, too…cover crops.

There Are Short-Term Impacts of Cover Crops

Cover crops are not a new technology.  They were grown regularly in ancient Roman vineyards, as well as in ancient China and India. In fact, the 1938 USDA Yearbook of Agriculture touted their benefit as an erosion control practice. However, after spending many years in obscurity, cover crops have found their way back into the mainstream. With potential benefits extending well beyond erosion control, recent studies have focused on cover crops’ impact on the entire production system, as well as the environment as a whole.

A recent study by scientists from Pennsylvania State University and Cornell University modeled the impact of a soybean-wheat-corn rotation with and without cover crops on various soil, crop, and economic conditions over a three year period. Cover crops included in the simulation were red clover after winter wheat and cereal rye after corn. 

A win-win
The results of their model showed that cover crops had a positive effect on a number of soil and production factors. Over the three year simulation, total plant biomass production, nitrogen mineralization (nitrogen release), and soil carbon storage increased in the cover crop scenario as compared to the non-cover crop scenario. The model also found cover crops increased the amount of beneficial fungi and insects, while decreasing weed populations, nitrate loss, and soil erosion. The computer simulation also predicted the red clover cover would supply approximately 150 pounds of nitrogen per acre to the following corn crop.

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Cover crops can help conserve moisture, keep soil covered and provide residue going into the cropping season. Download our free report Cover Crops: Best Management Practices

These results confirm what cover cropping advocates around the nation are saying; cover crops provide a "win" for soil fertility and biology, as well as water quality. 

However, how do cover crops affect a farm’s bottom line? The simulation found crop yields to be equivalent between the cover cropped and non-cover cropped system.  The researchers determined that in their specific scenario, the increased costs associated with planting and terminating cover crops exceeded the benefits of reduced nitrogen fertilizer inputs by approximately $26 per acre, using 2012 input prices.  However, their analysis did not include potential reductions in pesticide use or cost-sharing or incentive programs associated with cover crop use.

With continued use, the author stated improved ecosystem functions associated with cover crop use may enhance a cropping system’s resiliency to outside forces, such as extreme weather events, thereby stabilizing yields. Additionally, potential reductions in fertilizer and pesticide requirements could increase production system profitability, particularly if input costs continue to rise. 

So, what’s the study’s bottom line? 

Cover crops have the potential to positively impact crop production and environmental quality, even over the short time period modeled in the study.  Although the study did not find a bump in crop yield after cover crops, producers completing the 2012-2013 Sustainable Agriculture Research and Extension Cover Crop Survey reported a 9.6% increase in corn yields and 11% increase in soybean yields after cover crops when compared to yields from similar fields where no cover crops were grown. Arguably, these increases in yield alone could offset the additional costs of including a cover crop in a rotation.

So, interested in learning more about cover crops? Stop by your local NRCS or UW-Extension office.  If you want to see cover crops up close and personal, visit me at the UW-Extension demonstration plots outside the Applied Technology Tent at this year’s Wisconsin Farm Technology Days in Stevens Point Aug. 12-14.  We will have 30 cover crop monocultures and mixes on display. And who knows, maybe after talking cover crops, you can teach me how to text message!

The 2012-2013 SARE Cover Crop Survey available here.

Patton is the Shawano County Extension agriculture agent.

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