What benefits (and challenges) can the planting green system bring to soybean production?

cover crop

Nunes, Arneson & Werle


February 28, 2023

Adopting a cereal rye (Secale cereale) cover crop can be a valuable tool for integrated waterhemp (Amaranthus tuberculatus) management when enough cereal rye biomass is accumulated in the spring before the cover crop termination. By enough, we mean 4,500 lbs per acre or more of dry cereal rye biomass. But if you are a soybean farmer in the upper US Midwest, where heat accumulation between fall and spring is a limiting factor for cover crop growth, achieving such levels of biomass in the spring might take a while and require more than just planting a cover crop in the fall (proper cover crop management is necessary). That is where the “planting green system” comes in to help provide your cover crop an opportunity to accumulate adequate levels of biomass (≥4,500 lbs acre) for effective waterhemp suppression (Figure 1).

If you are not familiar with this system, planting green is when the cover crop termination is postponed until or after the soybean planting to give the cover crop extra time to grow. So instead of terminating the cover crop one to two weeks before soybean planting (which most farmers adopting cover crops currently do), the termination is done when the soybean crop is established to help the cereal rye cover crop accumulate those valuable 4,500 lbs of dry biomass for effective waterhemp suppression. Another potential benefit of this approach is that in case you are planning to spray a PRE-emergence herbicide at soybean planting (which we hope you do), you can combine the chemical cereal rye termination (glyphosate serves that purpose very well according to our research) and the PRE-emergence soil residual herbicide applications all in one pass.

Figure 1. Soybean “planting green” system.

The one fear most farmers have regarding this system is the potential soybean yield drag (which concerns us too). We know that soybeans are resilient, and when the cover crop is terminated well in advance of soybean planting, yield reduction is typically unlikely. But what about this planting green idea? To answer this question, we conducted a study over the past two growing seasons (2021 and 2022) to evaluate if the planting green system can help with waterhemp suppression without impacting soybean yield. To give you a more robust answer, besides Wisconsin, we had the help of academic weed scientists from Arkansas, Missouri, Iowa, Illinois, Indiana, Kansas, Kentucky, North Dakota, Ohio, and Pennsylvania to replicate the study and gather a large amount of data. Here is what we have learned from this United Soybean Board sponsored effort thus far:

Moving from planting soybean in conventional tillage, or even no-till, to a system with cover crops is a big step. There is a lot to learn and adapt to, and oftentimes we learn those lessons the hard way. So, our goal with this article is to share the lessons (good and bad) we have learned thus far from this project with you (farmers and practitioners). Because when it comes to cover cropping and planting green, there is a steep learning curve, and we can all benefit from each other’s experiences.

Figure 2. Cereal rye stand and growth on April 29, 2022, near Brooklyn, WI (O’Brien Family Farms).

The research reported herein is being led by Jose Junior Nunes (WiscWeeds PhD student). Click here to see Nunes’ slides presented during the 2022 North Central Weed Science Society Meetings (December 2022) in St. Louis, MO. Nunes won second place with this paper presentation (congrats Jose!).

Additional resources:

This article was written by Jose Junior Nunes (PhD Student), Nick Arneson (Outreach Program Manager), and Rodrigo Werle (Assistant Professor). All authors are affiliated with UW-Madison.