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Cover Crops and Sweet Corn – Supplement to CCSI-HAT Soil Health Podcast Season 3 Episode 9

Sweet corn farmers Chuck Mohler from Northern Indiana and Tom and Victor Hackman from Southern Indiana agree: cover crops are a benefit on any farm.

On the sandy soils of the Hackman Family Farm all but the earliest planted corn is no-tilled. They used to use wheat as a cover crop but started using cereal rye about five years ago and like it. Its roots are a good benefit. When rye is used, the Hackmans kill it chemically before it heads out and then no-till plant the corn. They like the way the rye residue helps to conserve moisture in the soil; even without irrigation unless there is an extreme drought they usually do ok. The residue also suppresses weeds, sometimes to the point where they don’t need a post-emergence herbicide application. The rye cover crop also reduces compaction in the field driveways. Wind erosion is a big concern on the sandy soils and the combination of a cover crop and no-till helps to ‘hold the soil where it is.’

Chuck Mohler agrees that rye is a good cover crop; one of many he uses on his heavier soils. Rye’s ability to grow in the cold is especially important in his more northern location. All of his sweet corn is planted in tilled ground. Beds are made in the fall for the early sweet corn that is planted in April. That corn is covered to protect from the cold and speed its growth so it will be ready by early July. He uses many kinds of cover crops to maintain and build the organic matter and microbial populations. They keep the soil fluffy and soft so the high-powered ‘super-sweet’ corn varieties will be able to emerge from the soil. After the early corn is harvested, he plants a cover of sudangrass and oats; watering and fertilizing just as though it were a cash crop. It makes a huge amount of biomass that gets turned back into the soil.

At the Pinney Purdue Ag Center in 2020 we are getting experience with no-till sweet corn following a rye cover crop. The rye was broadcast into soybeans in October 2019, shortly before they were harvested. In spring 2020, two replications of four treatments were established:

· BARE: rye killed by tillage April 27 and two additional passes before seeding

· HERB: rye killed with glyphosate May 21, no-till seeding

· RPRE: rye killed by roller-crimper just before no-till seeding

· RPOST: rye killed by roller-crimped just after no-till seeding

Sweet corn varieties ‘Catalyst’ and ‘Flagler’ were seeded on June 9 with a John Deere 7000 planter. We saw large differences in emergence by 9 days after seeding. For rows seeded at the same depth setting, emergence was close to 70% in BARE, 40% in HERB, and 10%-20% in RPRE and RPOST.

The differences were probably partly due to problems getting the seed in the ground: there were many more seeds observed on the surface in RPRE and RPOST plots than in the HERB or BARE plots. The planter we used did not do a good job of getting seed into the furrow and covering it in plots where rye had been allowed to grow. Another likely reason for the difference in emergence is soil moisture. In the 20-day period from May 29 to June 18 only 0.19 inch of rain was recorded. We observed that the BARE and HERB treatments had more soil moisture than the treatments where rye had been allowed to grow until planting. More corn did emerge after an irrigation on June 18.

We plan to continue to follow the corn progress in the different treatments. Already we realize that we will need to work on planting equipment to improve stand establishment, and pay closer attention to soil moisture at planting time in order to have a workable system. I’m sure we will learn more as the season progresses.

Sweet corn no-till planted on June 9 into standing rye that was then killed by roller-crimping. Pinney-Purdue Ag Center, July 7, 2020.

Sweet corn no-till planted on June 9 into rye that had been killed with glyphosate on May 21. Pinney-Purdue Ag Center, July 7, 2020.


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