Articles

Planting Green with Reduced Herbicides Improves No-Till Soybean Production

Planting green increases cereal rye biomass and can increase soybean yield compared with earlier termination or no rye. With a 1-pass program, it provided late-season weed control and yields similar to a 2-pass program without cover crops.

Download Save for later Print

Updated:

December 16, 2025

Skip to the end of the images gallery

Soybeans growing in cereal rye mulch that was terminated after planting. Credit: Grant Hoffer, 2023

Skip to the beginning of the images gallery

Investigators

Grant Hoffer, Research Technologist, Penn State Weed Science Program
John Wallace, Ph.D., Associate Professor and Extension Weed Management Specialist

Background

Planting green is an emerging practice by which cash crops are planted into living cover crops, which are then terminated after cash crop planting. Delaying the termination of cover crops can increase biomass production, which improves the potential for early-season suppression of many summer annual weeds. Planting green can improve crop performance by conserving soil moisture during periods of drought stress. Planting green also has the potential to improve the return on investment by facilitating a reduction in the use of residual (pre-emergent or PRE) herbicides.

Objective

The goal of this experiment was to investigate how planting green and reduced herbicide programs influence early-season weed suppression, late-season weed control, and soybean yield. This experiment is conducted as part of coordinated research efforts by Getting Rid of Weeds (GROW; growiwm.org) and has been replicated for three years across nine soybean-producing states and two sites per state.

Methods

The experiment was replicated at two sites at the Penn State Russell E. Larson Agricultural Research Center in Rock Springs, Pennsylvania, each year in the 2023–2025 production seasons. We began experiments after corn silage and corn grain, representing two fall establishment windows. Cover crop treatments included (1) no-cover-crop control, (2) cereal rye planted at 60 lb/A and terminated two to three weeks before soybean planting (Enlist system), and (3) cereal rye planted at 60 lb/A and terminated one to three days after soybean planting. Weed management treatments included a one-pass system (POST, glufosinate/2,4-D choline) and a two-pass system (PRE, Fierce XLT fb; POST, glufosinate/2,4-D choline). We sampled and weighed the biomass of the cover crop before each termination. Before making the POST application and at the soybean R1 growth stage, we counted weed density in each plot by species to estimate the weed control efficacy of each treatment. At the end of the year, we harvested soybeans at the plot level to detect treatment effects on yield.

Results

Planting green increased cereal rye biomass by 125% compared to the early-termination treatment. Biomass ranged from 5,500 lb/ac after corn silage to 2,500 lb/ac after corn grain in planting green treatments. The analysis of weed recruitment was separated by large-seeded species (velvetleaf) and small-seeded species (waterhemp). Generally, the presence of cover crops moderately reduced weed recruitment, whereas the use of PRE herbicides resulted in minimal weed recruitment. Soybean yield was significantly higher in both cereal rye treatments (early termination, planting green) compared to a no-cover-crop control, with an increase ranging from 5 to 7 bu/ac (Figure 1). Late-season weed control was similar across cover crop and herbicide-program approaches.

A bar chart titled “Soybean Yield” shows grain yield (in bushels per acre) for three cereal rye treatments: No cover crop, early termination, and planting green. For each treatment, two bars compare No PRE and PRE herbicide programs. Yields range from about 50 to a little over 60 bushels per acre. No cover crop shows slightly lower yields overall, early termination shows moderate improvement, and planting green shows the highest yields, with PRE and no PRE values close to each other within each treatment. — Figure 1: Soybean yield by cover crop treatment and presence or absence of pre-emergent (PRE) herbicide.

Conclusion

Planting green has the potential to produce weed control and yield benefits in a production sequence of cereal rye followed by soybean. Our results demonstrated a soybean yield benefit when integrating cereal rye before soybean. Also, integrating reduced herbicide programs (POST only) with planting green can result in similar late-season weed control and soybean yield to 2-pass (PRE/POST) herbicide programs with or without a cereal rye cover crop. Together, these results suggest that planting green can produce both production and conservation benefits in no-till soybean production systems.

Acknowledgements

Funding provided by the USDA-ARS-Areawide Pest Management (AWPM) program. Thank you to Getting Rid of Weeds (GROW) and the other GROW Legacy collaborators for contributing to this research.