Cover Crops Before Corn: Is there a corn yield drag following a rye cover crop?

Key Project Details

• Rye is a beneficial cover crop in Wisconsin to reduce soil and nutrient losses, but concerns about impacts on the following corn crop limit adoption.
• Evaluate the effect of rye cover crop on soil protection, crop yield, and overall profitability compared to a no-cover-crop control.
• Project includes a routine soil test, cover crop biomass sampling and cover crop nutrient analysis (estimated minimum budget: $230/field), with option to include additional expenses, sampling costs, and incentive payments in the budget.
• Interested in taking a deeper dive into cover cropping before corn? This project includes optional research packages so farmers can further explore topics that support management decisions on their farms. Optional research packages investigate nitrogen dynamics, pest pressure, additional cover crop species, or management comparisons.

Project Background

Although cover crops have demonstrated benefits to soil health and water quality, and many Wisconsin farmers are having success with rye due to its later planting window, good soil coverage and overwintering, concerns about negative impacts on the following corn crop limit widespread adoption.

This research trial aims to address the question, “Is there a corn yield drag following rye?” to evaluate potential conservation and economic tradeoffs, while collecting insights from participating farmers on challenges they face and how they are managing their cover crops to find success. As a collaborative producer-led research trial, results will provide relevant insights for your operation and contribute to a wider effort to support the advancement of conservation throughout the state.

Why Participate?

Learn through data from your farm. Whether you are a long-term cover cropper or new to the practice, gain farm-specific insights on how a rye cover crop may affect corn yield for your soils, management, and growing conditions. Interested in taking a deeper dive into cover cropping before corn? The project includes optional research packages to tailor the project to your goals.

Connect with other participating farmers to see how your results compare to others in the project and hear how others are managing cover crops prior to corn to be successful.

Contribute to a larger effort to support farmer-led conservation solutions and resources that can benefit other Wisconsin farmers. Results from this project will be aggregated, analyzed and shared to support other farmers with successful cover crop adoption.

Project Objective

Evaluate the effect of rye cover crop on soil protection, crop yield, and overall profitability compared to a “no cover crop” control. To address this objective, participants will include rye cover crop and no cover crop test strips (see example trial layouts) and measure cover crop biomass, cover crop nutrient uptake, and corn yield for each test strip.

Cover Crops Before Corn: Farmer-Led Research Project Summary

What will I learn?

The project evaluates the effect of a rye cover crop on soil protection, crop yield, and overall profitability to address farmers’ questions about the benefits and risks of cover crops before corn. In addition, through a coordinated effort, results from across a network of farms can provide insights into how soil, management, and weather may impact these results and support future decision-making.

How is this project designed?

This project compares two treatments: 1) no cover crop, the “control,” and 2) rye cover crop. Farmers can manage the rye (ex: seeding, termination) however works best for their system. For those newer to cover cropping, Extension can provide support navigating these decisions for your trial.

To best address the objectives of the study, participants will repeat (“replicate”) each treatment in the same field (see example trial layouts). This helps to confidently answer whether or not the cover crop impacted yield, when yield tends to be very variable in most fields.

What information is collected to address these goals?

Data collected includes routine soil tests, cover crop biomass & nutrient uptake, corn yield, and detailed field history and management information. Cover crop measurements help assess the benefits of rye cover crops, including soil protection, nutrient uptake, and weed suppression, while improving our understanding of cover crop decomposition and its potential impact on yield.

Where should I implement this project?

Any field that will be going into corn (grain or silage) is eligible for this project. All management decisions (ex: fertilizers, herbicides) are up to the participating farmer.

Extension’s on-farm research team is here to assist along the way. For those participating in the project you will receive technical support with setting up the trial, implementing it and collecting relevant data. General guidance on trial layout and data collection are included below as you consider this project, but more details and technical support will be provided directly to those participating.

Example Trial Layout

Our goal is to keep producer-led research trials simple and practical for participating farmers. Including multiple “test strips” in a field can provide an accessible way to implement these trials while still providing quality data on any impact to corn yield. Since yield is inherently variable even under the same management, replicating treatments is a way to confidently understand if any difference in yield is due to the rye cover crop rather than just natural variability.

This protocol recommends that each treatment is replicated three times. Full-field test strips that are three widths of the combine will be easiest for harvest data collection, but we can work together to set up a trial that works for you, your fields and equipment. Potential layouts include:

Timeline

Time of Year	Project Activities
Fall	Planning: select field and trial layout Routine soil tests Cover crop seeding: include rye cover crop and no cover crop comparison strips Cover crop visual assessment: observations, photos, and height
Spring	Cover crop biomass, lab nutrient analysis, and photos (prior to termination) Cover crop termination and corn planting (any method and timing)
In-Season	Occasional field visits, observations, and photos
Pre-Harvest	Prepare for harvest data collection (organize for a weigh wagon or calibrate yield monitor) Harvest and record yield data for each cover crop and no cover crop strip
Post-Harvest	Complete field history, management, and trial observation survey Share field and lab results for analysis Discuss individual & project-wide results

Data Collection for this Project

Field measurements, farmer-reported management information, and any observations are used to meet the objectives of this trial, interpret individual trial results, and support wider recommendations developed from research results.

• Routine soil test
• Cover crop sampling & nutrient content: including photos, cover crop biomass & nutrient content (spring) in each of the cover crop test strips. Option to include cover crop sampling in the fall.
• Corn yield: using a calibrated yield monitor or weigh wagon
• Field Management Data (including field history, management details, and any other observations)
• Optional data: explore optional research packages or discuss with our team if there are other measurements you are interested in.

Participants will receive data collection sheets and guidance on submitting data, which will be analyzed and summarized into a research report by UW-Madison Extension. At the end of the season, participants and partners will review and discuss individual results and connect with other participants about project-wide results.

Budget Considerations

Groups are encouraged to budget for this project to best meet their goals and priorities. All projects should budget for a routine soil test, spring cover crop nutrient analysis, shipping of samples and any sampling equipment. For a trial with three replications, the estimated cost for the minimum required data collection is $230/field. Given that analysis fees are subject to increases, groups are encouraged to reach out to their lab of choice for up-to-date costs.

In addition, groups are encouraged to budget for any additional expenses they wish to cover. This may include farmer participant stipends or incentive payments, labor for trial set-up or sampling, mileage, cover crop seed and management expenses, field day activities, or other additional measurements. Any questions on eligible costs can be directed to the specific grant or funder, if applicable.

Optional Research Packages

Interested in taking a deeper dive into cover cropping before corn? Tailor this research trial to answer your cover cropping questions with the following project packages:

Participants are encouraged to select one or combine research packages to address their management considerations, while balancing time and budget requirements.

Rye and Nitrogen Dynamics

Track soil nitrate and ammonium through the season to evaluate nitrogen dynamics for your field and conditions.
In addition to covering the soil to reduce risk of soil erosion, rye cover crops take up soil nitrogen following the cash crop to reduce nitrate leaching risk. However, there are concerns about how this impacts corn nitrogen needs due to potential nitrogen immobilization as cover crops break down in the spring. Measuring soil nitrate and ammonium through the season can provide insights to better understand potential water quality benefits, yield impacts, and future nitrogen management considerations.

• Low effort: requires additional soil sampling, 4 times throughout the season
• Soil samples are taken for each cover crop and no cover crop test strip in the fall prior to the first winter freeze (0-1’, 1-2’), spring pre-plant (0-1’, 1-2’), pre-sidedress (0-1’) if sidedressing nitrogen, and post-harvest (0-1’, 1-2’) and will be analyzed for nitrate and ammonium.
• Estimated budget for required sampling: $750 for additional sampling and $230 for baseline requirements (total is $980 per field).

Rye & Pest Pressure

Evaluate pest pressure throughout the season to better understand benefits and risks of integrating cover crops.
While cover crops have the potential to suppress weed pressure, there are unknowns of how other pests, like slugs, respond in high-residue conservation cropping systems. Evaluating weed, slug, and other observational pest pressure across rye cover crop and no cover crop treatments can provide insights on how cover crops can be an effective pest management tool for your operation.

• Low effort: requires additional in-field assessments and observations throughout the season
• Visual assessments of weed pressure and early-season slug monitoring will be conducted in each cover crop and no cover crop test strip. Slug monitoring requires weekly visits to count slugs on the traps (visit SlugNet for more information).
• Estimated budget for required sampling: Register at SlugNet to receive supplies for no additional cost. Total sampling costs are $230 per field.

Cover Crop Species Comparison

Are you curious about other cover crop options to provide conservation benefits while minimizing risk of yield drag?
Evaluate another cover crop species alongside rye and no cover crop control on yield, soil protection and profitability. This project compares three treatments: 1) no cover crop, the “control”, 2) rye cover crop, and 3) a cover crop species of your choosing, such as a multispecies mix, camelina, winterkill grass (ex: oats).

• Medium effort: requires additional cover crop treatment and sampling for both cover crops in the fall and spring.
• Cover crop biomass measurements and nutrient analysis are recommended in both fall and spring to compare the two cover crop species for conservation benefits (soil protection, nutrient uptake) as well as any potential impact to the following corn crop.
• Estimated budget for required sampling: $830 per field for all cover crop nutrient analysis and routine soil test. If these costs are too expensive, reach out to discuss alternative nutrient analysis options that are more affordable.
• Interested in using cover crops as forage? Add forage quality analysis to your cover crop sampling!

Management Comparison

Explore different management practices to minimize risk of yield drag while maintaining conservation benefits of a rye cover crop.

Management decisions such as cover crop termination timing, nitrogen management, and tillage management are important for finding success with rye before corn. Compare additional management scenarios across the no cover crop and rye cover crop treatments and how management might impact conservation benefits, yield, and profitability.

• High effort: requires two management scenarios (ex: early vs. late termination timing) across the rye and no cover crop treatments.
• Recommended trial layout: balancing an additional management practice can be challenging in an on-farm research trial. Splitting the field in half will be easiest for participants to implement and manage the two management scenarios (see diagram below). Participants can explore management comparisons they are most interested in. Examples include:
  • Early cover crop termination vs. later cover crop termination
  • Split nitrogen application vs. nitrogen applied at sidedress
  • No-till vs. strip till
• Estimated budget for required sampling: $430 per field for all cover crop nutrient analysis and routine soil test.

Unsure if this project is right for you? Reach out to our team for more information on what you will learn, how to implement the project, or how to budget for it in an upcoming grant.

About Collaborative Producer-Led Research and Demonstration Projects

This project is a collaborative effort of Wisconsin farmers, DATCP’s Producer-Led Watershed Protection Grant Program, UW-Madison Division of Extension, and many local partners and collaborators to support producer-led research, demonstration, and education. Protocols are designed with producers to support farmer-driven conservation solutions, farmer-to-farmer learning, and coordinated data on conservation practice performance across Wisconsin.

Thank you to the Farmer Working Group for their support in developing this protocol.