Updated March 30, 2021:
Due to continued economic and climatic pressures, farmers in the Northeast are looking for ways to increase on-farm feed production and diversity their operations to increase resilience and profitability. Soybeans could be grown for human consumption, animal feed, and biodiesel in Vermont. However, farmers face challenges due to the relatively short growing season and limited research-based information available in our area. The purpose of our trials is to evaluate soybean yield and quality under conventional and organic growing conditions, when planting dates are varied, and under various tillage regimes following fall planted cover crops. Understanding how crops are impacted by varying planting dates and tillage strategies can help producers make important management decisions that lead to better crop success. With a growing concern of agriculturally related water quality implications in Vermont waterways, farmers are now required in some instances to cover crop their annually cropped fields. However, with this increase in cover cropping there is a need to investigate potential impacts on following cash crops and best practices for establishing cover crops into and following soybeans. Similarly, with the concerted effort to reduce nutrient loading in waterways due to soil erosion, farmers are becoming more interested in adoption reduced and no-till practices. Understanding how to best combine these two practices into soybean cropping systems specifically for the Northeast is critical to the success of soybean crops in Vermont.

This year we initiated several soybean trials at Borderview Research Farm in Alburgh, VT. These trials include a variety trial, a planting date trial, and a cover crop trial in which soybeans follow fall planted cover crops under varying tillage regimes. This report will summarize our research and outreach activities around these trials thus far this season.

Variety Evaluation Trial

The variety trial included twenty varieties, sourced from four seed companies, spanning maturity ratings 0.7 to 2.1. The trial was planted on 21-May 2020 into a Covington silty clay loam at a rate of 185,000 seeds ac-1 treated with soybean inoculant and receiving 5 gal ac-1 9-18-9 starter fertilizer. Throughout the season the trial was inspected for insect and disease issues however due to extremely hot and dry conditions very little disease and insect pressure was seen until September. On 17-Sep plots were assessed for severity of infection with downy mildew (Peronospora manshurica), brown spot (Septoria glycines), frogeye leafspot (Cerospora sojina), white mold (Sclerotinia sclerotiorum), and damage from chewing insects, primarily Japanese beetles. These were the only pests and diseases observed in the trial. Assessments were made by inspecting each plot and assigning a rating (0-5) where 0 equated to damage/infection not present and 5 equated to infection or damage present on 100% of leaf area. White mold incidence was measured by counting individual affected plants in each plot as the infection primarily was isolated to stems. The percent of each plot experiencing lodging was estimated visually. On 15-Oct, the soybeans were harvested using an Almaco SPC50 small plot combine and yields, moisture, and test weight recorded. Soybean oil was extruded on 14-and 16-Dec using an AgOil M70 oil press and the amount of oil captured and measured to determine oil content and oil yield.

Warm and dry conditions allowed for all soybeans to reach maturity; however moderate drought conditions resulted in some production issues. Wildlife pressure was substantial in the trial leading to the loss of several plots and in one case the inability to evaluate the yield performance of a variety entry. Drought conditions appeared to force lots of wildlife into agricultural fields. Harvest moisture ranged from 13.0 to 14.4% indicating that little additional drying was needed for most of the soybeans to reach an adequate moisture level for storage. Test weights ranged from 54.8 to 58.7 lbs bu. All soybean varieties produced test weights below the industry standard of 60 lbs bu. This was likely influenced by the drought conditions that persisted through the season, especially during critical developmental stages including pod formation and seed fill. Yields ranged from 46.1 to 81.6 bu ac-1 and averaged 65.3 bu ac. These data suggest that soybeans from maturity groups 0.0-2.0 can produce high yields in northern climates. However, it is important to note some large differences between varieties even within similar relative maturities. These data highlight the importance of utilizing local variety evaluation information in variety selection. Soybean oil content also differed significantly by variety ranging from 4.65% to 12.4%. Oil yields ranged dramatically from approximately 24.4 to 76.2 gal ac.

Planting Date Trial
One of the goals of this planting date study was to determine how late soybeans can be planted in Vermont while still reaching maturity and producing adequate yields. In addition, we wanted to determine how soybeans respond to shifting planting dates in terms of other characteristics such as pest and disease pressure. The planting date trial contained two varieties, one early and one mid-group 1 maturity. Plots were planted approximately weekly from 14-May through 2-Jul. Plots were 20’ long and consisted of two rows spaced at 30 inches. The seeding rate was 185,000 seeds ac. Plots were monitored for pest and disease pressure throughout the season. On 9-Jun, early planting dates were scouted for slug damage, however no damage was observed. Plots were assessed on 6-Aug and 15-Sep for growth stage, lodging, and pest/disease incidence. No major pest or diseases were observed so a formal scouting was not conducted. On 14-Oct, the soybeans were harvested and weighed for plot yield, tested for harvest moisture and test weight using a DICKEY-John Mini-GAC Plus moisture and test weight meter. Soybean oil was extruded from the seeds with an AgOil M70 oil press on 14-Nov, and the amount of oil captured was measured to determine oil content and oil yield.

Interactions
There was a significant variety x planting date interaction for yield, harvest moisture, and test weight indicating that the maturities responded differently in terms of these variables when planted on different dates. Generally, as planting dates become later, farmers must modify varieties, selecting maturities to fit the remaining length of the growing season. Hence, with later planting dates generally shorter season varieties begin to outperform longer season types. Although this trend was not observed in our 2018 and 2019 trials, in 2020 we saw soybeans in the early (0.9) maturity group produce higher test weight soybeans across all but the latest planting dates where they were more similar to the test weights of the late (1.7) maturity group. This was likely a result of an early frost limiting seed fill in both varieties. conditions had on soybeans regardless of planting date. The significant interaction between variety and planting date for harvest moisture indicated as planting dates were delayed, both the early and late maturity group varieties experienced a decline in harvest moisture until the 6th planting date, after which time the harvest moisture greatly increased for both groups which was likely a result of the early frost. The significant interaction between relative maturity and planting date for yield indicates that later maturing variety out yielded the early maturing variety in early planting dates, both varieties experienced significant yield declines as planting dates were delayed beyond mid-June and the early maturing variety did not outperform the late maturing variety at these dates. This indicates that, even for shorter season varieties, delaying planting until late June or later will have a significant impact on soybean yields.

Impact of Variety
The two soybean maturities performed significantly different in terms of harvest moisture and test weight but were statistically similar in all other harvest characteristics. Moisture at harvest was 0.5% lower in the short season variety. Test weights varied slightly between varieties with the earlier maturing variety producing seed with a test weight of 0.6 lbs bu higher than the later maturing variety. Yields averaged 44.7 bu ac and did not differ statistically between the two varieties. Oil content and oil yield also did not differ between varieties.

Impact of Planting Date
Soybean planting dates performed statistically differently in all harvest characteristics except for oil content. Harvest moisture ranged from 16.2% to 21.6% with lower moisture being produced when planting dates ranged between 21-May through 12-Jun. Test weights ranged from 52.6 to 56.7 lbs bu. Higher test weights were produced when soybeans were planted between 21-May through 12-Jun. Soybean yields ranged from 25.3 to 56.9 bu ac with the highest yields being obtained when planting between 28-May and 19-Jun. However, the first two planting date yields were likely negatively impacted by an erroneous herbicide application. These data suggest that delaying planting to late June and beyond negatively impacts soybean yields in this region.

Impact of Cover Crops on Subsequent Soybean Yields

The treatments were 10 cover crop monocultures or mixtures planted on 20-Aug 2019. Treatments consisted of cover crops that would over winter and others that would be terminated by winter conditions. Fall biomass samples were collected on 29-Oct 2019 and for over wintering cover crops on 28-Apr 2020, cover crop height and ground cover were measured in all plots. Soil health samples were also collected from all plots and air-dried and prior to being sent to the Cornell Soil Health Laboratory (Ithaca, NY) for analysis. All cover crop treatments were terminated on the 14-May using a moldboard plow and disc harrow. On 12-Jun 2020, the soybeans were planted into the terminated cover crop treatments and plot were harvested on 15-Oct, the soybeans were harvested using an Almaco SPC50 small plot combine. Seed was cleaned with a small Clipper M2B cleaner (A.T. Ferrell, Bluffton, IN). They were then weighed for plot yield and tested for harvest moisture and test weight using a DICKEY-John Mini-GAC Plus moisture/test weight meter.

In the fall, the highest yielding treatment, oats, was statistically similar to three other treatments (Oat/radish, Annual ryegrass/radish, and Oat/crimson clover). All cover crop treatments had fall yields that were significantly greater than the control. In the spring, the winter rye had the highest biomass, 2.07 tons ac, which was statistically greater than all other treatments. The triticale produced the second highest spring biomass, 1.73 tons ac. Typically, in the region, annual ryegrass is winter-killed, but mild winter conditions allowed for the cover crop to survive into the spring. The annual ryegrass and the annual ryegrass/radish treatments produced 1.00 tons ac-1 and 0.66 tons ac respectively. All other treatments were winter-killed and did not produce any spring biomass. The cover crop treatment had no statistically significant impact on soybean yield or test weight in 2020 and the trial average was 3486 lbs. ac. The average test weight was 56.6 lbs. bu. Soils were analyzed for soil nitrate-N (NO3) concentration starting from mid-May through the end of June. Overall, soil nitrate-N (NO3) was highest in plots that had the radish cover crop treatment. The radish treatment had significantly greater soil NO3-N than all other treatments on three of the soil sample dates (12-May, 19-May, and 15-Jun). On all five dates, both triticale and winter rye treatments had soil NO3-N concentrations that were not significantly different than the control. Cover crops did not enhance or diminish yields in the subsequent soybean crop.

Cover Crop Termination Methods for Soybean Cropping Systems

Treatments included three tillage termination methods and two over wintering cover crops. Termination types included incorporation of the cover crop 2 weeks before planting, herbicide termination 2 weeks before planting, planting green followed by herbicide termination. Cover crops included cereal rye and triticale. On 5-May and 19-May cover crop biomass was measured prior to termination in each treatment. To understand the nutrient release rates of the different cover crop treatments and how this is impacted by termination method, soil nitrate and moisture content were assessed in each plot prior to termination and biweekly following termination and planting. On 22-May, the soybeans were planted into each of the termination treatments and harvested on 15-Oct.

Cover crop biomass was significantly different between treatments, prior to termination. The tillage treatment had the most spring cover crop dry matter, 2.24 tons ac and was statistically similar to the planting green treatment, 2.16 tons ac. Soybean yield was statistically different between the termination methods. The pre-spray treatment had the highest subsequent soybean yield with 71.5 bu. ac; the tillage treatment (65.9 bu. ac) was statistically similar to the pre-spray treatment. Planting green resulted in the lowest yields (42.6 bu ac). There was no significant difference in soybean test weight between the cover crop termination methods.

Prior to cover crop termination, there was no significant impact of cover crop type on spring soil cover or cover crop dry matter yield. The average cover crop dry matter was 1.90 tons ac-. There was also no significant impact of cover crop treatment on the subsequent soybean harvest. Average soybean yield for this season was 60.0 bu. ac and test weight was 56.5 lbs. bu.

Soil moisture was significantly higher in the tillage treatment than in the pre-spray and post-spray treatment. The pre-spray treatment had significantly higher soil moisture than the post-spray treatment on 2-, 9-, and 15-Jun. There were no differences in soil moisture between the pre-and post-spray treatments on the remaining five dates. It is possible that the soil moisture was lower in pre- and post-spray treatments because the overwintering cover crops had more time to grow in the spring, removing some of the soil moisture. In a normal year this may not impact the cash crop, but in a dry year, especially with a season-long drought, there could be negative impacts on soybean yield. The tillage treatment had significantly higher soil temperature on all dates; the pre-and post-spray treatments were not statistically different from one another on 13- and 21-Jul. It makes sense that soil temperatures were lower in the pre- and post-spray treatments because the cover crop was sprayed but left unincorporated to act as a mulch, protecting soil microbes and preventing the soil from further drying out.

Soils were analyzed for soil nitrate-N (NO3) concentration starting from 12-May (a week prior to soybean planting) through the end of June. There were no statistical differences in soil NO3-N between the three termination methods on 12-May. From 19-May through 29-Jun, the tillage treatment had the greatest amount of soil nitrate-N and was significantly greater than both the pre- and post-spray treatments on all four dates. The pre-spray treatment had significantly greater soil NO3 than the post- spray treatment on 19-May and 29-Jun. On 15-Jun, there was spike in soil NO3-N in the post-spray treatment, making it significantly higher than the pre-spray treatment. Cover crops take up nutrients like nitrogen and store it in plant biomass, as seen with the pre- and post-spray treatments. For comparison, the plow down of cover crops releases that nitrogen by putting the soil in contact with the biomass and allowing for the decomposition of the plant material.

Overall, cover crop termination strategy did impact soybean yields. Given that it was a dry season the cover crop terminated after planting might have resulted in less soil moisture for the soybean growing in this treatment. Early season growth might have been limited by moisture and available nitrate. It is difficult to determine if this early season setback might have caused such a substantial reduction in yields.


Outreach
Outreach this last year was different to say the least. Our main mode of outreach during the summer months are typically on-farm workshops and field days which typically attract hundreds of farmers, technical service providers, and other agricultural professionals. We were able to share our research results at our annual No-Till Cover Crop Symposium which attracted 133 attendees, and a Certified Crop Advisor training just before the COVID-19 pandemic hit Vermont. The remainder or our typical in-person events were canceled since March, yet we worked to continue to provide farmers with valuable, research-based, and season relevant information through other modes of communication. This included posting to our blog and social media accounts, creating written resources that can be accessed via our website, webinars and Virtual Friday Field Days. As a result, we were actually able to reach more stakeholders with 316 participants in our webinar series and 217 at our Virtual Field Day Fridays Series. We also posted our research reports to our website where they will remain available.

Blogs:

https://blog.uvm.edu/outcropn/2020/05/27/time-to-plant-soybeans/

https://blog.uvm.edu/outcropn/2020/06/25/watch-out-for-slugs/

https://blog.uvm.edu/outcropn/2020/03/15/dig-into-your-daywith-cover-crops-conservation/

Virtual Events:

https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/Virtual%20Field%20Day%20Fridays/opening_slide_-_welcome_FDF.pdf

https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/CoverCropWebinarSeries_Advertizment_pub.pdf

Reports:

https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Conventional_Soybean_VT_Report_Final.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Conventional_Soybean_VT_Summary.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Organic_Soybean_Variety_Trial_Report.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Organic_Soybean_VT_Summary_Final.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Soybean_PD_x_Var_Report.pdf
https://www.uvm.edu/extension/nwcrops/research
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Cover_Crop_Termination_Trialdocx.pdf

View uploaded report

As farmers in the far northeast region look for ways to reduce feed costs and diversify their operations, soybeans are becoming increasingly popular. However, these farmers need region specific information to help them succeed in producing high yielding soybean crops while protecting the natural resources on and around their farms.

This project met several of the Eastern Soybean Growing Region Board research priorities including a focus on high yielding soybeans and soil health.

All projects were conducted in the most northwestern corner of VT. The soil type is characterized as a silt loam with 1 to 2% slope.

The weather during the 2020 growing season can be characterized as warm and dry. Above average temperatures and below average precipitation persisted through the summer months. Early frost was experienced in September, shortening our already short growing season.

Objective 1 was to identify soybean varieties that produce maximum yields in the far north. The experimental design was a randomized complete block with 4 replicates. The treatments were 20 varieties with maturity groups ranging from 0.7 to 2.1.

The average yield for the entire trial was 60.3 bushels of soybeans per acre. The top performing variety yielded 81.6 bushels per acre and had a maturity rating of 1.8. Other varieties that performed statistically similar to this top performer had maturity ratings ranging from 0.9 to 2.0.

Overall, these data suggest that soybeans in maturity groups 0, 1, and 2 can produce high yields under in far northern climates. Data gathered from the last 4 years indicates that high soybean yields can be obtained from a wide range of maturity ratings in far northern regions. However, based on the data highest yields have been obtained from varieties that fall within the 1.0 and 2.0 maturity group.

Objective 2 was to determine optimal soybean planting dates for the far northern regions. The experimental design was a randomized complete block with split plots and 4 replicates. Main plots were eight planting dates from mid-May through early-July. Subplots were two varieties with a maturity of 0.9 and 1.7.

The highest soybean yields were obtained from planting dates between May 28th and June 12th. It is expected that, as planting dates are delayed, short season varieties will begin to outperform full season varieties. However, in this trial, both maturity groups suffered depressed yields once planting dates were delayed beyond mid-June despite adequate GDDs. This was likely due to impacts of drought conditions and an early frost. These data suggest that delaying planting to late June and beyond negatively impacts soybean yields in this region.

After evaluating planting date of soybeans in the northern regions from 2017 to 2020, it can be summarized that planting late-May into early-June generally always resulted in the highest yields. Planting earlier or later in all years provided additional risks.

Objective 3 is to develop cover cropping strategies for soybean production systems that maximize yield, protect soil health, and minimize pest and disease pressure.

The goals of this trial were: 1) to investigate the impact of various cover crop species and mixtures on subsequent soybean yield and quality and 2) investigate the impact of termination methods on soybean yields and quality. For simplicity, methods and results will be presented for these objectives separately.

Impact of Cover Crops on Subsequent Soybean Yields

Treatments were 10 cover crop mixtures that included both overwintering and winterkilled species. The highest soybean yield of 94 bushels per acre was achieved when no cover crop was present. However, this was statistically similar to all cover crop treatments indicating that utilizing a cover crop did not significantly impact the following soybean crop yield.
Soil was analyzed throughout the season to better understand nitrogen availability following overwintering and winterkilled cover crops. Soil nitrate levels were higher in overwinter plots from early June through mid-July suggesting that the nitrogen in the incorporated living cover crop material was mineralized by mid-July. However, this extra nitrogen did not impact soybean yield.

Impact of Cover Crop Termination on Subsequent Soybean Yields

Cover crop termination methods were also investigated. Treatments included pre-planting incorporation via conventional tillage, a pre-plant herbicide application, and a post-planting herbicide application (planting green).

Soil nitrate levels were significantly higher in conventionally tilled plots followed by pre-plant herbicide and post-plant herbicide treatments. This trend continued until early July when the pre-plant herbicide treatment produced soil nitrate levels similar to the conventional tillage treatment. Soil moisture was significantly higher in the tillage treatment than in the pre-spray and post-spray treatment. The pre-spray treatment had significantly higher soil moisture than the post-spray treatment on 2-, 9-, and 15-Jun. There were no differences in soil moisture between the pre-and post-spray treatments on the remaining five dates. It is possible that the soil moisture was lower in pre- and post-spray treatments because the overwintering cover crops had more time to grow in the spring, removing some of the soil moisture. In a normal year this may not impact the cash crop, but in a dry year, especially with a season-long drought, there could be negative impacts on soybean yield.

Overall, cover crop termination strategy did impact soybean yields. Given that it was a dry season the cover crop terminated after planting might have resulted in less soil moisture for the soybean growing in this treatment. Early season growth might have been limited by moisture and available nitrate. It is difficult to determine if this early season setback might have caused such a substantial reduction in yields.


Outreach

Outreach this last year was different to say the least. Our main mode of outreach during the summer months are typically on-farm workshops and field days which typically attract hundreds of farmers, technical service providers, and other agricultural professionals. We were able to share our research results at our annual No-Till Cover Crop Symposium which attracted 133 attendees, and a Certified Crop Advisor training just before the COVID-19 pandemic hit Vermont. The remainder or our typical in-person events were canceled since March, yet we worked to continue to provide farmers with valuable, research-based, and season relevant information through other modes of communication. This included posting to our blog and social media accounts, creating written resources that can be accessed via our website, webinars and Virtual Friday Field Days. As a result, we were actually able to reach more stakeholders with 316 participants in our webinar series and 217 at our Virtual Field Day Fridays Series. We also posted our research reports to our website where they will remain available.

Blogs:

https://blog.uvm.edu/outcropn/2020/05/27/time-to-plant-soybeans/

https://blog.uvm.edu/outcropn/2020/06/25/watch-out-for-slugs/

https://blog.uvm.edu/outcropn/2020/03/15/dig-into-your-daywith-cover-crops-conservation/

Virtual Events:

https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/Virtual%20Field%20Day%20Fridays/opening_slide_-_welcome_FDF.pdf

https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/CoverCropWebinarSeries_Advertizment_pub.pdf

Reports:

https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Conventional_Soybean_VT_Report_Final.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Conventional_Soybean_VT_Summary.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Organic_Soybean_Variety_Trial_Report.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Organic_Soybean_VT_Summary_Final.pdf
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Soybean_PD_x_Var_Report.pdf
https://www.uvm.edu/extension/nwcrops/research
https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Cover_Crop_Termination_Trialdocx.pdf