There are many good reasons that cover crops are increasingly being grown on Mid-South acreage. Among those reasons: erosion prevention, weed suppression, water quality benefits, and improving soil characteristics.

Michele Reba, a USDA-ARS research hydrologist, has been quantifying many cover crop benefits at research sites around the Arkansas Delta and the Lower Mississippi River Basin. One of the speakers at the recent, NRCS-sponsored Southern Agricultural Cover Crops Workshop held in Jonesboro, Ark., Reba explained how cover crops can positively impact farmland.

“The hydrologic cycle begins with precipitation that infiltrates into the ground and eventually runs off into waterways. The cycle continues with evaporation and transpiration back to the atmosphere, eventually forming clouds and the cycle begins again.

“So, consider a crop that is put on land during a period when the field would normally be fallow. The very general question is: how would that crop impact the hydrologic cycle? Cover crops can have a great impact.”

How so?

“First, there is precipitation. A cover crop, during winter, will likely trap more snow on the land.

“Evaporation is altered with the cover crop as it impacts radiation, wind, and vapor pressure deficit. Changes to radiation impact surface temperatures.”

Reba said work done by other researchers, “suggests that with crops, you may be able to increase surface temperatures. There won’t be as large a diurnal fluctuation in soil temperatures with cover crops.”

As a result, producers may be able to “plant a bit earlier because you may have warmer soil temperatures.”

The other large body of research associated with the hydrologic cycle and cover crops is the impact of run-off and how cover crops affect that. “Cover crops will reduce the amount of water coming off the landscape and leave more of it in the field by increasing infiltration rates.

“Soil profile storage capacity is also impacted by cover crops through macropore geometry and macrofauna activity.  Again, allowing for more water to enter the ground and remain available to the field instead of running off.”

Among Reba’s other comments:

On different reasons to plant cover crops…

“In the northeastern part of Arkansas, there are fields where a cover crop is grown prior to planting cotton. That is to reduce the amount of wind erosion that the young cotton seedlings experience.

“In other areas farmers are using cover crops as ‘catch crops.’ That’s where a cover crop is grown to catch available nitrogen in the soil. That prevents leaching losses.”