The UVM Extension Northwest Crops and Soils Program (NWCS) has provided farmers with up-to-date information on soybean varieties that produce maximum yields in the far north over the past six years thanks to funding from the Eastern Soybean Board. Our 2021 Soybean Variety Trial report, along with past reports, can be found on our Research Results webpage. However, variety selection is just one piece of the puzzle.
To be successful in today’s challenging economic and environmental climate, farmers need region specific information that will not only lead to high yields, but also reduce environmental impacts. Soybeans are grown for human consumption, animal feed, and biodiesel, and can be a useful rotational crop in corn silage and grass production systems. Cereal or winter rye is commonly planted in this region as a cover crop. As cover cropping expands throughout Vermont, it is important to understand the potential benefits, consequences, and risks associated with growing cover crops in various cropping systems. In 2021, the NWCS Program initiated a trial to investigate the impact of cover crop termination method and cover crop biomass on soybean yield and soil health. The experimental design was a randomized complete block with split plots and four replicates. Main plots were cover crop termination methods including tillage and herbicide application applied before and at planting. Sub-plots were varying levels of cover crop biomass created by seeding winter rye (var. Hazlet) at rates ranging from 0 to 150 lbs per acre.
Spring soil coverage was positively correlated with seeding rate. While this was expected, interestingly, there was no impact of seeding rate on cover crop dry mater yield; no additional cover crop yield was gained by increasing seeding rates beyond 50 lbs ac-1. The cover crop termination method had a greater impact on cover crop biomass production and subsequent soybean harvest. The plant green treatment produced twice as much cover crop dry matter, compared to the other two treatments, due to the later termination date. However, soybean yield was negatively correlated with cover crop biomass. The plant green treatment had soybean yields that were 1.3X less than the tillage and herbicide treatments. Additionally, the planting green treatment had a significant impact on soil moisture. As noted, 2021 was an exceptionally dry growing season until harvest. The winter rye cover crop, like other crops, needs moisture to grow. Allowing the cover crop to grow longer means the need for more moisture. Unfortunately, the depleted soil moisture in this treatment was constant across the season because of below average precipitation. This likely contributed to the significant reduction in soybean yields.
It is crucial to continue to investigate cover cropping practices in soybeans in this region to gain a better understanding of successful cover cropping practices and their impacts on soybean performances, especially as we see an increase in adverse weather conditions. We would like to thank Eastern Soybean Region Board again for the funding for this trial. The Eastern Region Soybean Board aims to provide farmers with cutting-edge research they can use to better manage their crops. Visit their webpage to learn more about this research! There you will find links to the final reports of previous years projects done by Dr. Heather Darby at the University of Vermont.
Read the full 2021 Soybean Cover Crop Termination Trial report linked here. And stay tuned for research updates because the UVM Extension NWCS Program plans to repeat this trial this year!