In 2017, the University of Vermont Extension Northwest Crops and Soils Program investigated the impact of various cover crop mixtures on a subsequent soybean crop’s yield and quality at Borderview Research Farm in Alburgh, VT. Soybeans are grown for human consumption, animal feed, and biodiesel and can be a useful rotational crop in corn silage and grass production systems. 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 an effort to support the local soybean market and to gain a better understanding of cover cropping in soybean production systems, the University of Vermont Extension Northwest Crop and Soils (NWCS) Program, as part of a grant from the Eastern Soybean Board, established a trial in 2017 to investigate the impacts on soybean yield and quality of following annual cover crop mixtures with a soybean crop

Cummings, Erica

Darby, Heather

Gupta, Abha

Ruhl, Lindsey

Ziegler, Sara

English

UVM ScholarWorks

University of VermontScholarWorks @ UVMNorthwest Crops & Soils Program UVM Extension2017Soybean Cover Crop TrialHeather DarbyUniversity of Vermont, heather.darby@uvm.eduSara ZieglerUniversity of VermontErica CummingsUniversity of VermontAbha GuptaUniversity of VermontLindsey RuhlUniversity of VermontFollow this and additional works at: https://scholarworks.uvm.edu/nwcspPart of the Agricultural Economics CommonsThis Report is brought to you for free and open access by the UVM Extension at ScholarWorks @ UVM. It has been accepted for inclusion inNorthwest Crops & Soils Program by an authorized administrator of ScholarWorks @ UVM. For more information, please contactdonna.omalley@uvm.edu.Recommended CitationDarby, Heather; Ziegler, Sara; Cummings, Erica; Gupta, Abha; and Ruhl, Lindsey, "Soybean Cover Crop Trial" (2017). NorthwestCrops & Soils Program. 71.https://scholarworks.uvm.edu/nwcsp/71 © March 2018, University of Vermont Extension   2017 Soybean Cover Crop Trial    Dr. Heather Darby, UVM Extension Agronomist Sara Ziegler, Erica Cummings, Abha Gupta, and Lindsey Ruhl UVM Extension Crops and Soils Technicians  (802) 524-6501   Visit us on the web at: http://www.uvm.edu/extension/cropsoil 2017 SOYBEAN COVER CROP TRIAL Dr. Heather Darby, University of Vermont Extension heather.darby[at]uvm.edu  In 2017, the University of Vermont Extension Northwest Crops and Soils Program investigated the impact of various cover crop mixtures on a subsequent soybean crop’s yield and quality at Borderview Research Farm in Alburgh, VT.  Soybeans are grown for human consumption, animal feed, and biodiesel and can be a useful rotational crop in corn silage and grass production systems.  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 an effort to support the local soybean market and to gain a better understanding of cover cropping in soybean production systems, the University of Vermont Extension Northwest Crop and Soils (NWCS) Program, as part of a grant from the Eastern Soybean Board, established a trial in 2017 to investigate the impacts on soybean yield and quality of following annual cover crop mixtures with a soybean crop.  MATERIALS AND METHODS  The trial was established at Borderview Research Farm, Alburgh, VT in the fall of 2016. The experimental design was a complete randomized block design with four replications. The treatments were 10 cover crop mixtures planted on 6-Sep 2016. Treatments consisted of mixtures that would both be over-wintered and some that would be winter-killed.  Cover crop treatments and seeding rates are listed in Table 2. Cover crop living biomass was determined in the fall prior to winter dormancy. Cover crop was measured again in the spring just prior to soybean planting (4-May 2017). Ground cover was assessed via the beaded string method (Sloneker and Moldenhauer, 1977) and biomass was collected from a 0.25m2 area in each plot. The biomass was weighed and dried to determine dry matter content and dry matter yield. Soil was sampled within each plot at a depth of 6” and a width of 2” on 12-May. These samples were submitted to the Cornell Soil Health Testing Laboratory (Geneva, NY) for wet aggregate stability analysis. All cover crop treatments were terminated just prior to soybean planting using a moldboard plow and disc harrow (Table 1).  Table 1. Trial management details, 2016-2017.  Borderview Research Farm-Alburgh, VT Soil types Benson rocky silt loam 8-15% slope Previous crop  Annual cover crop mixtures Tillage operations Moldboard plow and disc Plot size (feet)  5 x 20 Row spacing (inches) 30 Replicates 4 Starter fertilizer (lbs ac-1)  200 lbs ac-1 10-20-20 Planting dates Cover crops: 6-Sep 2016 Soybeans: 29-May 2017  Weed control 1 qt ac-1 RoundUp Power Max 5-Jul 2017 Harvest date 13-Oct 2017 On 29-May 2017, the soybeans were planted into the terminated cover crop treatments using a Monosem NG-Plus 2-row precision air planter (Edwardsville, KS) at 185,000 seeds ac-1 with 200 lbs ac-1 starter fertilizer (10-20-20). The variety SW1055 (maturity group 1.0, Genuity® RoundUp Ready 2 Yield) soybean was obtained from Seedway, LLC. (Hall, NY) for the trial. Soybeans were sprayed with RoundUp Power Max herbicide on 5-Jul to control weeds. On 13-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 using a Berckes Test Weight Scale. Table 2. Annual cover crop mixture treatments grown in 2016 prior to soybean in 2017. Mixture # Species Variety Cover crop over-winters Seeding rate lbs ac-1 1 Annual ryegrass Fria yes, ryegrass only 22 Tillage radish Eco-till 3 2 Forage rape Dwarf Essex yes, triticale only 3 Triticale Trical 815 60 3 Forage turnip Appin yes, clover and triticale only 2 Red clover Dynamite 3 Triticale Hyoctane 60 4 Forage turnip Appin yes clover and winter rye only 2 Red clover Dynamite 1 Winter rye VNS 40 5 Annual ryegrass unknown no 18 total (premixed) Tillage radish Arifi 6 Annual ryegrass unknown no 24 total (premixed) Crimson clover unknown Tillage radish Arifi 7 Forage oats Everleaf no 40 Forage turnip Appin 2 Red clover Duration 5 8 Forage oats Everleaf no 60 Tillage radish Groundhog 31 9 Red clover Mammoth yes, clover and triticale only 5 Forage brassica T-Raptor 2 Winter pea Lynx 20 Winter triticale Fridge 40 10 No cover crop N/A N/A  Yield data and stand characteristics were analyzed using mixed model analysis using the mixed procedure of SAS (SAS Institute, 1999).  Replications within trials were treated as random effects, and hybrids were treated as fixed.  Hybrid mean comparisons were made using the Least Significant Difference (LSD) procedure when the F-test was considered significant (p<0.10). Variations in yield and quality can occur because of variations in genetics, soil, weather, and other growing conditions.  Statistical analysis makes it possible to determine whether a difference among hybrids is real or whether it might have occurred due to other variations in the field.  At the bottom of each table a LSD value is presented for each variable (i.e. yield).  Least Significant Differences (LSDs) at the 0.10 level of significance are shown.  Where the difference between two hybrids within a column is equal to or greater than the LSD value at the bottom of the column, you can be sure that for 9 out of 10 times, there is a real difference between the two hybrids.  In this example, hybrid C is significantly different from hybrid A but not from hybrid B.  The difference between C and B is equal to 1.5, which is less than the LSD value of 2.0.  This means that these hybrids did not differ in yield. The difference between C and A is equal to 3.0, which is greater than the LSD value of 2.0.  This means that the yields of these hybrids were significantly different from one another.   RESULTS  Weather data was recorded with a Davis Instrument Vantage Pro2 weather station, equipped with a WeatherLink data logger at Borderview Research Farm in Alburgh, VT (Table 3). Overall, the season was cooler and wetter than normal. More than 1.5 inches of rain fell within 10 days following planting. Unseasonably cool temperatures and above average rainfall persisted through August followed by above average temperatures and below average rainfall in September and October. The dry warm weather in the fall provided good weather for the soybeans to mature and to be harvested at optimal moisture content. Overall, a total of 2335 growing degree days (GDDs) were accumulated June-October, 209 above the 30-year normal. Despite these unusual growing conditions, the soybeans appeared relatively unharmed and produced very well.  Table 3. Weather data for Alburgh, VT, 2017. Alburgh, VT June July August September October Average temperature (°F) 65.4 68.7 67.7 64.4 57.4 Departure from normal -0.39 -1.90 -1.07 3.76 9.2             Precipitation (inches) 5.64 4.88 5.54 1.84 3.3 Departure from normal 1.95 0.73 1.63 -1.80 -0.31             Growing Degree Days (base 50°F) 468 580 553 447 287 Departure from normal -7 -60 -28 129 175 Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger. Historical averages are for 30 years of NOAA data (1981-2010) from Burlington, VT.  Table 4 summarizes the cover crop production and soil health characteristics in the spring for each treatment. The treatment that produced the most biomass in the fall was treatment 1 (annual ryegrass/tillage radish) which produced 2104 lbs ac-1. This was statistically similar to six other treatments. Treatments 3 and 4, which both included turnip, red clover, and a winter grain (triticale and winter rye respectively), both produced the lowest biomass but were statistically similar to one another. Of the five treatments that survived the winter, treatment 9, which contained red clover, forage brassica, winter pea, and triticale, Hybrid Yield A 6.0 B 7.5* C 9.0* LSD 2.0 produced the most biomass with 1494 lbs ac-1. In reality only the triticale and clover survived the winter and produced that spring biomass. It is interesting that this treatment, despite having a lower seeding rate of triticale compared to treatment 2 (triticale/rape) produced significantly more biomass in the spring. Furthermore, winter rye is traditionally regarded as the species that produces the most biomass in this region, however, treatment 4, the only treatment containing winter rye, was one of the lowest producing treatments in the fall and produced half the biomass of treatment 9 in the spring.   Treatments did not differ in the percent ground cover that they provided. This suggests that, even cover crops that winterkill in our region can provide substantial ground cover in the spring to help protect the soil surface from the impacts of rainfall. Treatments also varied significantly in terms of soil aggregate stability. The highest aggregate stability was obtained by treatment 5 (annual ryegrass/tillage radish) with 33.4% aggregate stability. This was statistically higher than any other cover crop treatment. The next highest treatment was the oat/turnip/clover treatment with 26.5% aggregate stability.  Table 4. Cover crop and soil health characteristics, 2017. Cover crop mixture Fall biomass Spring biomass Ground cover Aggregate stability   -----DM lbs ac-1----- % 1 2104 127 43.0 22.7 2 1851* 987 52.0 26.1 3 1627* 140 49.5 24.7 4 1350 767 37.5 23.2 5 1837* 0 41.5 33.4 6 1935* 0 42.0 21.9 7 1883* 0 45.5 26.5 8 1183 0 28.5 25.5 9 2050* 1494 46.5 24.8 10 0 0 46 22.8 LSD (p = 0.10) 599 497 NS 5.01 Trial Mean 1582 352 43.2 25.2 *Varieties that did not perform significantly lower than the top performing variety  in bold are indicated with an asterisk. NS – No significant difference.  Soybeans were harvested on 13-Oct 2017. Table 5 summarizes the yield and harvest characteristics of soybeans from each cover crop treatment. Despite relatively wet and cool weather conditions through most of the growing season, the soybeans produced high yields with all producing at least 58 bu ac-1. The highest yielding treatment was treatment 6 (annual ryegrass/crimson clover/tillage radish) which produced 4541 lbs ac-1 or 75.7 bu ac-1, an incredible yield, especially for a region with such a short growing season. This was statistically similar to the control and treatment 5 (annual ryegrass/tillage radish). The lowest yielding treatment was treatment 3 (triticale/turnip/red clover) which only produced 3481 lbs ac-1 or 58.0 bu ac-1. Cover crop treatments did not significantly impact harvest moisture or test weight. Of the 10 cover crop treatments examined, five (mixtures 5, 6, 7, 8, and 10) did not produce living vegetation in the spring while the other five treatments did. Overwintering treatments produced on average 4073 lbs ac-1 or 67.9 bu ac-1 while the treatments that had living spring biomass produced on average 3625 lbs ac-1 or 60.4 bu ac-1 (Table 6). These data suggest that soybean yields may be negatively impacted by preceding overwintering cover crops (Figure 1). However, to fully understand this interaction, more data needs to be collected, such as nutrient content of the cover crop biomass and availability, as differences between mixture composition would likely impact soybean yields differently.  Table 5. Soybean harvest characteristics by cover crop treatment, 2017. Cover crop mixture Harvest moisture Test weight Seed yield @ 13% moisture   % lbs bu-1 lbs ac-1 bu ac-1 1 15.4 54.4 3727 62.1 2 15.3 54.8 3492 58.2 3 15.1 55.7 3481 58 4 15.1 55.4 3769 62.8 5 15.1 55.9 4051* 67.5* 6 14.8 56.7 4541* 75.7* 7 14.8 56.3 3839 64 8 15.4 54.2 3847 64.1 9 15.4 54 3657 60.9 10 14.6 56.8 4088* 68.1* LSD (p = 0.10) NS NS 614 10.2 Trial Mean 15.1 55.4 3849 64.2 *Varieties with an asterisk performed similarly to the top performer in bold. NS – No significant difference.  Table 6. Soybean yields by cover crop overwintering status. Overwinter Soybean yield   lbs ac-1 bu ac-1 Yes 3625  60.4 No  4073  67.9 LSD (p = 0.10) 265  4.42 Trial mean  3849 64.2  The top performing treatment is indicated in bold. DISCUSSION  Overall, soybeans produced high yields in 2017. Preceding a soybean cash crop with a cover crop can help retain excess nutrients that would otherwise be lost from the soil. However, using a mixture that includes a winter grain, such as winter rye or triticale, can present management considerations in the spring as they will overwinter and can produce a lot of biomass early in the spring. These data suggest that overwintering cover crop mixtures can reduce the yields of a following soybean crop. This may be due to the immobilization of nitrogen or other nutrient dynamics in the soil when the soybean crop is establishing. However, these dynamics were not investigated in this study. Further analysis will be conducted in order to determine potential differences between the mixtures, both that winterkill and overwinter, to identify best cover cropping practices that support high yielding soybeans in this region. Figure 1. Soybean and cover crop yield by cover crop mixture treatment, 2017. Treatments that share a letter performed statistically similarly to one another. Letters presented for cover crop yield indicated differences in total biomass. ABCABA ABCABCABDABcbacbcccccB BBB BB BAB ABA0.010.020.030.040.050.060.070.080.0050010001500200025003000350040003 2 9 1 4 7 8 5 10 6Soybean yield (bu ac-1)Cover crop dry matter yield (lbs ac-1)Cover crop treatmentFall CC yield Spring CC yield Soybean yieldREFERENCES  Sloneker, L. L. and W. C. Moldenhauer, 1977. Measuring the amounts of crop residue remaining after tillage. J. Soil Water Conserv. 32:23 l-236.   ACKNOWLEDGEMENTS  UVM Extension Northwest Crops and Soils Program would like to thank Eastern Soybean Region Board for the funding for this trial.  We would also like to thank Roger Rainville and the staff at Borderview Research Farm for their generous help with this research trial.  We would like to acknowledge Nate Brigham, John Bruce, Erica Cummings, Kelly Drollette, Hillary Emick, Amanda Gervais, Freddie Morin, Matthew Sanders, and Stuart Wolff-Goodrich for their assistance with data collection and entry.  We would also like to thank the seed companies for their seed and cooperation in these study.  The information is presented with the understanding that no product discrimination is intended and no endorsement of any product mentioned or criticism of unnamed products is implied.   UVM Extension helps individuals and communities put research-based knowledge to work.   Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. University of Vermont Extension, Burlington, Vermont. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.  

Soybean Cover Crop Trial

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Soybean Cover Crop Trial

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