Benefits of Planting Green and Key Considerations for Success
By Brandon Schmitz, SWOF Field Program Representative: Kansas and Southern Nebraska
Traditionally, cover crops are terminated about one to two weeks before planting corn or soybeans to avoid yield loss, but planting green—the practice of planting a cash crop into a living, actively growing cover crop—is gaining traction among farmers looking to increase efficiency and reduce input costs by naturally suppressing weeds.
While planting green offers significant benefits, success depends on careful management of soil moisture, nutrient availability, and planter set-up. We recommend that growers first start to plant green with soybeans, as they are highly adaptable to this practice. Here’s what you need to know to maximize the advantages of planting green and ensure a smooth transition into the growing season.
1. Soil Moisture
A major advantage of planting green with a cover crop is the ability to better manage soil moisture. Cover crops absorb excess moisture early in the season, actually allowing topsoil to dry out faster for planting. Their root systems also break up soil compaction, increasing water infiltration. During heavy rain events, cover crops have been shown to prevent runoff and reduce ponding on the soil’s surface.
A Penn State Extension study found that even though cover crops remove moisture early, planting green can help retain moisture later in the growing season. Because of the larger mass of residue from late-killed cover crops compared to a preplant-killed cover crop, decomposition is slowed and evaporation reduced. The higher soil moisture measured later in the growing season is beneficial when rain events can be less frequent (Reed et al., 2024).
The amount of soil moisture available at planting time is critical. Farmers should evaluate soil moisture levels and terminate cover crops one to two weeks before planting if dry conditions are expected, as it can be difficult for cash crops to establish.
Terminated cereal rye provides a nice weed suppressing mat as soybeans come up in this SWOF-enrolled field.
2. Selecting the Right Termination Method
To prevent competition with cash crops, cover crops need to be terminated at the right time. Choosing the right herbicide to terminate cover crops is essential. Some, like red clover, can be difficult to kill with herbicides that are safe for post-planting application.
The most common termination methods include:
Rolling/Crimping – A mechanical method that flattens the cover crop, creating a weed-suppressing mulch. Michigan State notes that, “Using a roller crimper to terminate cover crops can be effective under select conditions, particularly with crops that have later planting dates” (Sprague & Hill, 2024, p. 1). Optimal crimping timing for cereal rye or hairy vetch is at flower or anthesis. Most studies agree that utilizing a roller crimper in combination with herbicides increases the likelihood of successful termination. Roller crimping is not recommended for legumes, as heavier equipment is often needed to break their stems.
Herbicide Application – When selecting an herbicide program for cover crop termination, Purdue University recommends taking the following factors into consideration: cover crop species, the cover crop growth stage, any other weed species present, the production crop to be planted, weather conditions at application, and the type of herbicide used.
Glyphosate is a proven, effective means of control for covers in the grass species, including wheat, barley, cereal rye, oats, and annual ryegrass. It’s most effective when applied on warm, sunny days when plants are actively growing, and before the boot stage of grasses (Legleiter et al., 2024).
Always consult species-specific recommendations and weed control guides or herbicide labels to ensure effective termination.
Farmers should ensure that termination matches their planting schedule, allowing enough time for residue to break down without delaying cash crop emergence.
3. Nutrient Management and Soil Health
Timing and placement of nutrients play a key role in optimizing crop growth when planting green. A tailored nitrogen management program is essential to monitor the C:N ratio in each field. Grass cover crops, such as cereal rye, have low nitrogen content, which can lead to nitrogen immobilization in the soil when terminated. While soybeans can handle this due to their nitrogen-fixing abilities, corn may suffer from nitrogen deficiencies during early growth (Wilke, 2023).
After several years of trials on planting green, Penn State Extension recommends utilizing a split-application of nitrogen with corn: “applying approximately one-third to one-half N at planting and the remainder as a side dressing” (Reed et al., 2024). This will help meet the crop’s needs as the cover crop breaks down and releases nutrients over time.
A SWOF-enrolled farmer plants corn into a live cover crop in eastern Iowa.
4. Planter Set-Up and Depth
Most no-till planters work for planting green, though modifications can boost performance since this involves denser crop residue. Best practices include:
Using a no-till drill or planter with aggressive row cleaners to manage residue and improve seed-to-soil contact.
Adjusting closing wheels and closing wheel pressure to ensure proper seed placement and trench closure. Living roots can pose a challenge, but switching to a spiked closing wheel is an easy solution.
Increasing seeding rates if there are concerns about cover crop competition.
Continuously monitoring depth: Ideal planting depth is 1.5-2 inches for soybeans and corn, but heavy cover crop biomass requires an ¼ adjustment deeper to achieve the desired depth. Consider increasing your planter depth settings slightly or adjusting down pressure to ensure the seed gets in the ground. This can be achieved by tweaking the down pressure air bag, down-pressure springs, or using hydraulic/VR downforce if available.
Regardless of your planter set-up, it’s very important to get out and check your depth in every field, as conditions will be different in each one (Smith, 2024).
The Bottom Line
Planting green can be an effective strategy for improving soil health, managing weeds, and optimizing crop emergence. However, success depends on careful planning and adjustments based on soil moisture, termination methods, nitrogen needs, and planter setup. Farmers new to this practice may want to start small with soybeans, experimenting on a few acres to evaluate the benefits before scaling up. Over time, you’ll see firsthand how it can improve both your farm’s sustainability and bottom line.
The Soil and Water Outcomes Fund (SWOF) can help you maximize the benefits of these sustainable practices by providing financial and agronomic support. Contact us today to learn more!
Brandon Schmitz
Field Program Rep.
As our field program representative for Kansas and Southern Nebraska, Brandon Schmitz works with farmers as they implement conservation practices. He also provides support to referral partners. Brandon earned a bachelor’s degree in animal sciences and industry from Kansas State. He has several years of experience working in the ag industry. He was raised on a small hog and cattle farm in northeast Kansas. Brandon and his wife reside in the area with their two children. In his free time, he an avid bowhunter, enjoys K-State games, and helping his parents with the farm and livestock.
Sources and Additional Resources
For more in-depth research and best practices, check out:
Legleiter, T., Johnson, B., Jordan, T., & Gibson, K. (2024, February 9). Successful cover crop termination with herbicides. Purdue Extension. extension.purdue.edu
Reed, H., Karsten, H., Tooker, J., Duiker, S. W., & Curran, W. S. (2024, February 9). Planting green 101: Penn State research summary. Penn State Extension. extension.psu.edu
Smith, Daniel (2024, April 19). Watch: Planting green – planter setup. University of Wisconsin-Madison Extension. cropsandsoils.extension.wisc.edu
Sprague, C., & Hill, E. (2024, April 22). Cover crop termination. Michigan State University Extension. canr.msu.edu
Wilke, B. (2023, June 1). How can I make the best decision on whether to “plant green” this year or not? Michigan State University Extension. canr.msu.edu