Wondering how and when to terminate your cover crop? Perhaps planting green is right for you. This practice involves planting your corn or soybean crop directly into a cover crop like cereal rye or wheat — without terminating the cover crop first.
As with any cropping system, there are pros and cons to consider before making your decision. We’ve laid out the good, the bad and the ugly of planting green to help you choose whether to give this method a shot next season.
Benefits of planting green
Improve soil health by increasing organic matter inputs
Planting green into an existing cover crop significantly increases organic matter in the soil, adding biomass, improving soil structure, preventing erosion control and more.
Potential for improved yield
A 2023 Ontario study found that in fields planted green, corn yields were 28 bu/ac higher than the combined average yields across five farms in four counties.¹
Easier planting and better soil conditions
Planting into green cover crops is typically easier than planting into partially decomposing ones. Planting corn into decomposing, mushy cover crops has been known to slow emergence and result in yellow, weak seedlings.
Penn State research found that soil was 2% dryer when planting green,² making planting conditions more suitable than the typically wet, cold soil conditions that can hamper germination and increase risk of seedling disease.
Potential for weed and pest control
Planting green extends the cover crop growing season, allowing for the cover crop to produce more biomass and soil organic matter, and leading to more effective weed suppression.
Some growers have reported that planting green can reduce slug damage on subsequent crops.³ While a nationwide consensus hasn’t been reached, the concept of planting green is thought to both create habitat for slug predators and act as a food source for slugs, distracting them from the primary crop.⁴
Challenges of planting green
Poor emergence
When you plant green, it’s critical to get the cover crop seeding rate right. Planting a cover crop too densely can lead to yield loss as a result of poor emergence and poor growth of the primary crop, which has to compete for light and nutrients.
Increased pest risk
The risk of encountering certain soybean pests and corn pests can increase when planting green, as some cover crops may become infested with a pest that then transfers to the primary crop. For example, in 2017, wheat stem maggot proved problematic in fields where growers planted green, with some growers reporting losses of 30 bu/ac in fields with a high number of infested plants.⁵
Overall, pest management is typically more complicated when planting green because fields require additional scouting to detect possible pest problems.
Increased risk of nitrogen issues
Planting a legume cover crop can help suppress weeds (due to allelopathic effects) as well as provide nitrogen to the soil.
However, when planting green with non-legume cover crops, you will likely need to apply a higher-than-standard upfront nitrogen rate to help compensate for nitrate tie-up and cooler, slower-to-mineralize soils early in the season.⁶
Dry soil conditions
Dryer soil conditions can also work against you if weather conditions are already on the dry side. In a dry spring, terminating cover crops one or more weeks before planting your primary crop is recommended. Consider that different cover crops dry out soils at different rates; e.g., clover cover crops tend to dry out soil more quickly than rye.
Could you benefit from planting green?
To plant green successfully you’ll need an in-depth understanding of your region’s climate and a solid working knowledge of your primary crop, proposed cover crops, and the effects of planting rate, timing, and the other variables discussed here. While the cropping system requires careful management, if executed correctly, it can boost yield, streamline planting and reduce pest and weed pressure.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.
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Endnotes
- Munroe, Jake. “Does It Work to Plant Green into Cover Crops for Corn? Five Unique Ontario Fields in 2023.” Field Crop News – Ontario Ministry of Agriculture, Food and Rural Affairs in Partnership with the University of Guelph, 15 Mar. 2024, fieldcropnews.com/2024/03/does-it-work-to-plant-green-into-cover-crops-for-corn-five-unique-ontario-fields-in-2023/. Accessed 17 Nov. 2024.
- Mulhollem, Jeff. “‘Planting Green’ Cover-crop Strategy May Help Farmers Deal with Wet Springs.” The Pennsylvania State University. 1 July 2019, www.psu.edu/news/research/story/planting-green-cover-crop-strategy-may-help-farmers-deal-wet-springs. Accessed 17 Nov. 2024.
- Reed, Heidi, et al. “Planting Green 101: Penn State Research Summary.” Penn State Extension, 9 Feb. 2024, extension.psu.edu/planting-green-101-penn-state-research-summary. Accessed 17 Nov. 2024.
- Le Gall, Marion, et al. “Planted-green cover crops in maize/soybean rotations confer stronger bottom-up than top-down control of slugs.” ScienceDirect, Agriculture, Ecosystems & Environment, 15 Aug. 2022, www.sciencedirect.com/science/article/abs/pii/S0167880922001293. Accessed 17 Nov. 2024.
- Rees, Jenny, et al. “Considerations when Planting Green.” CropWatch, University of Nebraska-Lincoln, 24 Apr. 2020, cropwatch.unl.edu/2020/considerations-when-planting-green. Accessed 17 Nov. 2024.
- Munroe. “Does It Work to Plant Green…”
- Rees, et al. “Considerations when Planting Green.”
