Simultaneous Interseeding of Corn and Cover Crops at Various Row Spacings

Final report for FNC20-1209

Project Type: Farmer/Rancher
Funds awarded in 2020: $18,000.00
Projected End Date: 12/31/2022
Grant Recipient: Bowman Farm
Region: North Central
State: Illinois
Project Coordinator:
Andrew Bowman
Bowman Farm
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Project Information

Description of operation:

Mr. Bowman is a fifth generation farmer whose operation is located two miles north of Oneida, Illinois. He is the owner and partner running a 1,944 acre row-crop farm and at 33 has been recognized as the FFA National Star Farmer and Jaycees Outstanding Young Farmer. The farm has diversified into specialty popcorn production and has 35 acres certified organic with expectations to transition an additional 55 acres this year. His system has evolved to include strip-tillage fertilizer application, augmenting a no-tillage system. Organic transition efforts have been difficult as Bowman has refused to revert to excessive tillage for weed control. His farm would benefit from a cover crop interseeding system for soil biology, weed suppression, and improving fertilizer retention in an organic system. Bowman will contribute the no-till drill for modification as well as the other relevant equipment (including strip-tillage applicator, weed shocker, mower, flail chopper, tractors, and harvest equipment). He will also provide the larger of the plot areas as well as labor.

Bowman’s specialty popcorn business is further detailed at



Incorporating cover crops into row crop systems has been shown conclusively to be an economically viable, ecologically sound, and effective soil conservation and weed suppression method, both at a research and farm-scale level.

However, widespread interseeding of cover crops into a standing primary crop for general weed control and soil conservation purposes has been hindered because typical practice post-emergence interseeding requires multiple passes with specialized or highly modified equipment. Resulting cover crop performance is often mixed, with poor emergence, irregular establishment, and poor early competition with weeds especially in organic systems. Without seeing consistent results, farmers will be slow to adopt interseeding cover crops.

This project proposes:

  • To simultaneously plant a corn with a mixture of shade-tolerant cover;
  • To modify a no-till drill (for the cover-crops) by adding precision planting units (for the row-crop specialty corn), likely a modified Monosem twin-row, single-row or comparable precision planting unit; and
  • To compare cover crop and crop yield response to four corn planting widths: 5 inches (single row) 15 inches (single row), 30 inches (single row) and 60 inches (twin-row).

UPDATED from 2020 Lessons, Revised Objectives to be Measured for Harvest of 2022:

  • To plant corn into a standing, established cover via integration of prior cover crop seeding and strip tillage; and
  • To modify a vertical tillage tool that can be used for appropriate cover crop seeding prior to planting.

Success would yield economic gains, reduced pesticide load, and increased soil biodiversity while reducing workload for farmers.

Project Objectives:

The purpose of this grant was to investigate the feasibility of simultaneously planting corn and cover crops across various row widths for no-tillage, strip-tillage, and organic systems.  The original idea was to modify a drill that could seed the cover crops immediately at the same time as a planter that planted corn to establish a stand of cover crops, ideally perennial-decumbent types, with the end goal being greater soil health, weed control, and adequate-non-competitive co-existence with an annual corn crop.  Essentially, how do we create a “perennial living mulch” in a corn system that would improve biodiversity while maintaining a focus on the high-profit potential corn crop?

  1. To successfully establish a simultaneously interseeded specialty corn/mixed cover crop;
  2. To modify a no-tillage drill into an interseeder for both cover crop and row-crop planting in organic no-till and strip-till systems; and
  3. To compare the effects on corn yield and cover crop emergence and growth (height and biomass) of a high-density narrow row corn spacing (8.5 inches and 15 inches) versus standard (30 inch) and wide row spacing (60 inch twins).

UPDATED from 2020 Lessons, Revised Objectives to be Measured Harvest of 2022:

  • To plant corn into a standing, established cover via integration of prior cover crop seeding and strip tillage;
  • To modify a vertical tillage tool that can be used for appropriate cover crop seeding prior to planting; and
  • To showcase the results to passersby as well as clients of our partner cooperator thru signage, photographs, videos, data collection, press releases and field days.


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Materials and methods:

Materials Used:

  • No-Tillage 15’ Tye Drill $0 (existing implement on farm)
  • Monsem Precision Twin Row Units - $7,000 ($3,500 per row); $21,000 Total
  • Ag Leader Technology RTK Planting $0 (existing implement on farm) Provided
  • Precision Planting Technology
  • 20/20 Control Box                      $0 (existing implement on farm) Provided Delta Force                               
  • $2,650 per row                           $15,900 Total

2022 Updated

  • Valmar Seeder Modified onto 2630 John Deere Vertical Tillage Tool, Fall Seeding
  • RTK Enabled Strip Tillage
  • RTK Enabled Planter


  • Contiguous blocks of 8.5 inch, 15 inch, 30 inch, and 60 inch plantings
  • Each group will be replicated in a constant population block and a varied population block, this isolates population responses to row
  • Each replication will have a constant cover crop seeding The plot on the Youngquist land in Warren County will not have cover crop seeded so we can isolate for the response to competition between cover crop and corn (if any).
  • Each of these groupings will be replicated across two hybrids to isolate the hybrid

2022 Updated

  • 30 inch rows only. We scaled back for use to synchronize with RTK enabled strip tillage.

We arrived at this plot design as Bowman has some organic land which did poorly in 2021 and he is optimistic that twin-row 60” corn could resolve his problem by providing a safety valve for mowing in the event his organic acreage requires weed rescue. Youngquist has tested grid-planted, 12”x12” corn on a ¼ acre scale and thinks narrow rows are best. Both are anxious to understand how cover crops can be done economically for better help on the farm. The plot design accounts for cover crop competitive response, hybrid response, and population response to get a true understanding for what conditions this interseeding will work best.

Photo Bowman Youngquest

Research results and discussion:


2020 proved to be particularly challenging for our farm in administering this experiment—both logistically and in terms of weather considerations. 

  • First, the proposed system was amended prior to the season. We found, in researching best methods to amend the grain drill in the initial grant, that a better setup existed.  We swapped the drill for a Valmar 6056 seeding unit which could be placed between the tractor and planter.  This did not increase costs and was actually an improvement on the grant.  The challenge is that it did increase complexity trying to pull a planter for corn AND a cover crop separate implement with the same tractor—particularly with regard to hydraulic output requirements.  Further, visibility and turning radius were negatively, though not terribly, impacted by this altered setup.  Offsetting these negative challenges, it did make single pass planting possible.
  • COVID restrictions drastically limited the ability for field days to share and disseminate results and observations.
  • The partnership with Zackary Youngquist didn't work out, due to changing project needs and communication challenges. Matt Hulsizer—Andrew Bowman’s partner on the family farm—and Charles Martin—neighbor and separate SARE Grant Recipient—were able to step in and assist.
  • The no-tillage plot was seeded at a separate time and required additional strip-tillage to make possible. This plot, owned by Charles Martin, had an already well established stand of diverse covers.  This was valuable as it shows how this system COULD work in the future, but did not really help advance how well the cover crop seeding performed simultaneously would work alongside a corn planter.
  • The organic plots were a disaster nearly from the beginning. Only in our third year of organic production, we have not gotten weed control where it is sustainable—hence the desire for this SARE research to see how covers can fight weeds.  That said, the cover crops never did establish correctly.  The initial planting in the 60”, 30” and 15” rows looked beautiful for a few weeks and then were overtaken by waterhemp, giant foxtail, lambsquarters, and giant ragweed (in that order of weed density). 
  • Drought became a localized concern in west-central Illinois. We had a five week period from mid-July thru August that significantly set back late planted crops—which is exactly when the organic plot was planted.  This further exacerbated a negative weed competition effect.
  • Wind damage in early July harmed the conventional corn in the area as well. While not to the effect of the “Iowa deracho,” it was still causing yield drags from 30-50% off expected yields.  This played less of a role on the organic plot than the drought, but was still a contributing factor.
  • Yields were so poor across the board that the entire plot was harvested at a substantial loss with no real differences observed. The yield monitor could barely pick up the actual yields on any plot.
  • Lastly, what little qualitative data was generated vis a vis photos and notes, has been lost. It is unknown if this was poor organization or accidental deletion from Google Drive or a combination of both.

2022 Challenges

  • This modified approach had quite a bit of promise, except for fall of 2021 planting timing.  Due to 3" of rain in October, we were unable to get the cereal ryegrass established timely.  We were able to do this a week prior in fields 30miles west--which were unfortunately going into soybean so we could not switch crops--and they yielded a beautiful stand that did give us some interesting data.
  • The late planting resulted in no germination until 2022, at which point the biomass was too sporadic to functionally work for the objectives stated.
Participation Summary
2 Farmers participating in research

Educational & Outreach Activities

1 Webinars / talks / presentations

Participation Summary:

40 Farmers participated
5 Ag professionals participated
Education/outreach description:

A confluence of complicating factors prevented outreach activities in 2020.  First, the plot was planted late and then experienced severe drought right during grain fill.  The crop for the entire organic acreage was a failure, even the organic acreage outside the plot.  Second, there was a falling out with one of the providers.  Finally, COVID-19 prevented any outreach.

In August of 2022, we presented a session about our project to attendees of the National Strip-Tillage Conference.  This allowed for good dissemination of our findings as well as shared networking afterward.  Our presentation was recorded and made available for other participants as well.

Learning Outcomes

2 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Lessons Learned:

Lessons Learned

While we have no real data to show and no farmer events to host, we do have some very strong principles or conclusions that can be drawn moving forward with respect to a “perennial living mulch” in corn systems.

  • This is NOT a one-year research point, nor can the system be built quickly.
  • A novel integration of existing technologies will be required, but it appears all the “pieces of the puzzle” exist to make a perennial living mulch system in corn a reality.
  • It is absolutely true that perennials, not having been developed commercially for strong agronomics, first “sleep, then creep, then leap.” Our organic acreage, having entered its third year, has yet to have any of the perennials we seeded really take effect.  It now seems obvious that the premise for this grant was over-optimistic, given that on-farm observation.
  • The system must have strip-tillage integrated with annual reseeding and planting. Preliminary observations suggest that the following is the “ideal system”:
    • Start clean—prior to conversion to organic and/or a perennial living mulch system, make sure weed densities and fertility is under control.
    • Begin by fall seeding overwintering cover crops that can bring forth heavy biomass. Strip till in the fall and again in the spring as necessary to maintain a clean seedbed in the thick cover crops.
    • In the spring, prior to excessive vegetative growth, seed the perennials. Strip till or utilize a strip freshener in the spring again to maintain clean seed beds.
    • Allow the biomass on the covers to get waist high, then flail chop. Flail chopping allows planting to occur easily but maintains a heavy matt forcing weeds back but allowing established covers to grow.  Freshen the strip and plant the corn crop immediately.
    • Each fall, have a slightly lighter mix of covers and continue the process by adding perennials until it is only a small annual reseeding to maintain a good mix.
    • Plant a relatively early day corn plant with good emergence and drought tolerance.
    • It is assumed that planting into 60” twin rows – preferably with a Monosem “zipper” style that precisely places the seeds synchronized between each row—would be the absolute best system with minimal or zero yield drag. 60” rows also allow for rescue mowing between rows if weeds do break through the flail-chopped mulch of biomass. 
    • Using equipment on 30” centers is common and then the rows could be alternated each year. If planting on 60” twins is ideal, then the 30” center rows could easily be seeded with annual scavenger crops like radishes via the insecticide boxes on a traditional planter—this would make a truly mellow seed bed for the next year, especially when coupled with strip-tillage in the fall.
    • This system could be sped up if livestock were integrated (not an option with our participants). If you required alfalfa hay or another perennial stand for forage, this would be an ideal way to profitably establish the perennial covers and then bring in the reseeding/strip-tillage/planting necessary to integrate the annual corn crop.  Further, any failures—as we experienced in 2020—could be mitigated by having a livestock “crop” to utilize the “mess.”


Extension / Modifications Going Forward

Our farm intends to continue this project albeit under very different circumstances.  The aforementioned ideal system would require 3-5 years to implement. 

  • A new 8 row Monsem Plot planter has been purchased for our specialty popcorn business. We are researching converting to a twin-row on 60” centers.  A focused planter will help not just our popcorn enterprise, but this experiment as well.
  • Due to extensive wind damage across our farm last year, we had to purchase a John Deere 2623VT, vertical tillage implement to chop corn residue. This unit is perfect for sizing residue and we have already mounted the Valmar 6056 atop this tool for fall and spring vertical tillage.  This sets us up to apply cover crops effectively on many acres, not just this experiment.
  • A traded up strip-tillage bars from an old AgSystems NitroTill 6500 to a Landluver 9ton unit. The Landluver has a much heavier profile and more aggressive tillage for building larger berms.  
  • The goal is to use this new equipment to try doing this system as outlined above, but with annual crops for a few years with GMO corn as a “fail safe” to rescue with herbicide application if necessary. Once we hone in the system integrating strip till, flail chopping, and the annual cover crops, we can begin introducing perennial covers.

2022 Additional Lessons Learned

  • Planting timing is critical.  We observed excellent growth on the cereal ryegrass planted earlier in our further away fields which were dedicated to soybean production.  Logistics prevented us from getting to the allocated corn field for 2022.
  • On the timely planted cereal rye not part of the test, plant heights exceeded 31".  This would have been perfect for our project.
    • While we did NOT strip till into these fields as they were going into soybeans, had we done so, it would have been very interesting.  Our soybean planter had been retrofitted to have scrapers on the residue managers to prevent build up.  It was impressive planting into this.  It stands to reason that adding strip-tillage and flail chopping would make this even more impressive and yield weed control benefits.
  • While we are very disappointed in the results, it should be noted that it was not a total loss as the corn field did get a vertical tillage pass.  This allowed for a slightly warmer soil temperature at planting. 

Project Outcomes

2 Farmers changed or adopted a practice
2 New working collaborations
Success stories:

While this has been very disappointing overall with outcomes, I am proud of the tests we performed.  Interestingly, we have followed up with The Land Institute out of Kansas and are continuing this project but on a smaller scale and with a mix of Illinois native perennials.  The success story here is learning what didn't work, which is still helpful for our family farm as we evaluate ways to enhance our farm.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.