How cover crops rebuild soil biological life in a corn-soybean rotation

As 2022 opens, an encouraging sight here in northeast Iowa is bright green cover-crop fields scattered among fall-tilled cornfields and bare fields of soybean stubble. Our guess is about five out of 100 fields of corn or soybeans were planted to covers this fall. Mostly cereal rye.

January 3, 2022:  When we encourage our WakeUP clients to insert cover crops into their management, the usual reply is, "No time for that before it's too cold."

Indiana grower Hal Brown has more experience with soil biology and cover crops than anyone else we know. He considers winter covers his "fourth crop" after corn, soybeans and wheat. 

Drilling a wide mix of cover species after wheat is pretty achievable. But seeding covers, even cereal rye, after corn or soybeans is tough to achieve in time to give the cover seed time to develop vigorous roots before the soil freezes.

Hal and his son Ty have a dealership for Horsch equipment, and one specialty machine by Horsch lets them seed covers as they harvest. The first photo below shows the result: Well-established cereal rye seeded into corn. 

The Horsch hopper and blower ride piggyback on Hal's combine. Pneumatic tubes feed the seed into uniform distribution under the chopping rolls of the combine head. (Hal and Ty are also a Drago combine head dealer.)

Here are some notes Hal sent us recently, explaining his experience with cover crops: 

"Cover crops I can see growing... smell the soil again... raise organic matter levels... change the soil's condition.  Five dollars an acre of rye seed can give biological benefits, and you get the tillage also. A mature rye plant will have 385 miles of roots. And the root hairs on those roots will amount to 6,600 miles of hair roots.

"It works every year. Brings up more nutrients. Ties up excess N to be used later in the season. All win-win.  Farmers tell me they can't afford cover crops. I tell them to subtract the cover cost by reducing the same dollar amount of salt fertilizer from the co-op and you will be miles ahead.

"I was studying our Ward Labs soil tests yesterday, including the Haney tests. What I noticed was that we have zero percent base saturation of sodium. Which means no salt buildup in our soils. That is an exception rather than the rule. Our soil biology is free to grow with no salts! This results from the way we have been farming for many years, including use of cover crops.

"For years I was strip cropping, talking soil health, showing how soil biology did this and that, conducting field research.  It was like I was in a deep forest talking to the trees. No one listened. Now it's fashionable, and you at Renewable Farming have been a huge part of the reason!!" 

Vigorous cereal rye, seeded with Hal's combine attachment.
Hopper and blower for cover crop seed on back of combine