Developing Corn Silage Systems to Meet the Needs of Cover Crops

Final report for LNE18-361

Project Type: Research and Education
Funds awarded in 2018: $196,108.00
Projected End Date: 03/31/2021
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Project Leader:
Dr. Heather Darby
University of Vermont Extension
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Project Information

Summary:

Farmers have been rapidly adopting cover cropping, increasing in Vermont alone from 14,000 to 28,000 acres in one year. This interest is fueled in the desire to address field issues, mitigate environmental damage, and ultimately gain economic benefits. The existing set of cover crop resources focus primarily on the cover crop itself, without acknowledging additional factors in the production system. In order to increase access to cover crops and their full benefit, farmers need strategies that address the entire production system. Therefore, the goal of this project was to identify best practices for corn silage production that would result in successful establishment of interseeded cover crops. Three major factors including corn populations, corn variety selection, and timing of cover crop planting were evaluated through replicated on-farm and university research station trials. Corn silage varieties were evaluated to determine if variety characteristics will allow for better cover crop establishment. Corn populations, which have typically shifted to increase number of plants per acre, were evaluated for maintaining yield while also allowing for more cover crop growth. Finally the timing of cover crop interseeding was investigated as it plays a large role in determining adequate conditions (light) for growth.

During the project period, 8 farmers collaborated with the project team to host on-farm research trials. These trials evaluated the impact of corn variety, corn population, and cover crop interseed timing on the establishment of the cover crop and performance of the corn. These trials highlighted that variety selection has a large impact on corn yields and may influence the growth of the cover crop. Results were variable, with some years showing significant impacts from variety and others no impact on cover establishment. Corn maturity, ear type, and corn yield did not consistently impact cover crop establishment. As an example in 2020, the best cover crop establishment occurred in the highest yield corn silage variety.  It was clear that lowering corn populations to 30,000 plants per acre would maximize both corn and cover crop yields compared to higher or lower corn populations. Finally, interseeding the cover crop when there is adequate  light penetration through the corn canopy helped with establishment. It was determed that interseeding at early corn growth stages (V2 to V4) most consistently lead to adequate cover crop establishment. 

Thirty farmers enrolled in the program to determine the impact of interseeding on soil health and crop yields. These farmers made changes to corn silage practices including variety selection, reducing corn maturity, lowering corn populations, and modifications to lower residual herbicides. Soil health tests collected from the thirty farms that adopted practices showed a positive impact on cover crop establish resulting in soil health ratings moving from medium to high and farmers reporting an average yield increase of 1.2 tons per acre on 1395 acres of corn silage. An additional, 24 farmers were provided one-on-one technical assistance as well as access to interseeding equipment during the project period. A total of 54 farms adopted interseeding as a result of the project.

This project combined on-farm research and outreach/education methods to transfer information and knowledge to farmers.  In addition to gathering data at farm research locations, we utilized these sites for educational opportunities.  Locations were chosen to be conducive to effective research, but also to be geographically spread out to maximize our outreach efforts. The ability to show producers our results was major focus of our educational plan.  Seeing results first-hand in the field has a major impact on understanding and the rate of adoption.  In addition to the 10 on-farmfield days, we also developed other educational materials including the development of a “Guide to Interseeding Cover Crops” and 2 webinar series addressing practices that lead to successful establishment of interseeded cover crops. We also shared results at the No-Till & Cover Crop Symposium and other regional dairy and forage workshops in VT, ME, NH, NY. Ultimately the project information was able to reach 1,369 individuals at in-person events and another 1,647 individuals during virtual events for a combined audience of 3,016. 

 

Performance Target:

Twenty-five farmers will modify a corn silage practice, improve establishment of a cover crop, improve soil health ratings from medium to high, or report yield increases of 2 tons per acre on 500 acres of corn silage.

Introduction:

Farmers in the Northeast are rapidly adopting cover cropping.  Cover cropping in Vermont alone has increased from 14,000 to 28,000 acres in one year.  Farmers have identified the need to diversify cover crops and want to establish mixtures to address certain issues on their fields.  Nearly all cover crops planted in the northern regions focus on using winter rye as the primary cover.  Farms have noted that this cover crop has limitations with respect to certain issues the farmer may want to address (i.e. nitrogen production) and that it can be difficult to control in the spring.  In order for most farms in northern regions to establish cover crop mixtures, they must interseed the cover crop into standing corn.  New tools exist to interseed the crops similar to planting with a grain drill. Project partners have been successful at acquiring multiple pieces of interseeding equipment to be demonstrated on farms. This includes a PennState Interseeder (Interseeder Technologies, PA), Duo Inter-Seeder (Dawn Biologic, PA), and a High Clearance Cover Crop Interseeder (Haige Inc., IA).  Farmers are excited about this opportunity.  Preliminary work conducted by PI-Darby indicates that standard practices used to grow silage corn may actually reduce the establishment of interseeded cover crops.  To help farmers reap the benefits of diversified cover crop mixtures in the far northern stretches of the northeast, corn silage practices must be altered.  Silage corn is leafy and planted thick to maximize yield and quality of the forage.  Horizontal versus a vertical leaf structure increases shading of the soil reducing the ability of the planted cover crop to establish.  Long season varieties are planted to maximize the yield and growing season.  Many farmers have moved towards narrow row spacing (20 inch rows) reducing the ability of the cover crop to grow.  The use of fixed-ear corn varieties have allowed farmers to plant higher populations without compromising grain development.   Seeding cover crops when the equipment is available instead of seeding when the crop and field conditions are optimum have significant impacts on establishment of interseeded cover crops. Herbicides with residual are used to eliminate weeds in corn but limit cover crop establishment.  All of these practices do not promote growth of interseeded cover crops. Based on current research and farmer needs it is apparent that corn silage production strategies need to be altered to support successful interseeding of cover crops.

The proposed solution

Farmers have demonstrated their desire to cover crop and ability to integrate new practices into their operations. However, cover cropping research has focused largely on the cover crop itself and has neglected to acknowledge other factors in the system; farmers need strategies that encompass the entire production system in order to fully realize the benefits of cover cropping. Therefore, this project seeks to identify corn cropping best practices that result in successful establishment of interseeded cover crops.

Three major factors that need to be balanced in order for interseeding to be successful: corn plant characteristics, agronomics, and environmental conditions. Recent corn variety development has led to numerous varieties with a wide range of characteristics. By assessing the impact of these characteristics (leaf and ear architecture and relative maturity) we can determine optimal characteristics that increase light infiltration through the corn canopy increasing cover crop establishment.

Interseeding cover crops requires adequate soil moisture, light infiltration, and temperature throughout the establishment window. This has become more difficult in the face of increasingly erratic weather. Therefore, this project aimed to determine cover crop planting timings which balance the needs of the cover crop with environmental conditions and lead to successful establishment.

Finally, agronomic factors, such as herbicide selection and corn populations, also need to be adapted to support interseeding. Most herbicides used in corn silage systems have long residuals that inhibit the germination and growth of interseeded cover crops. Furthermore, silage corn is traditionally planted around 34,000 seeds/acre. However, yield reductions may not necessarily be seen if variety selection is considered when populations are reduced. Lower plant populations may allow for higher light infiltration and therefore cover crop establishment.

Farmers have a desire to produce high yield/quality crops and want to implement practices that allow for that goal to be achieved at the lowest cost. The rapid expansion of cover cropping indicates that farmers realize that integrating cover crops into their corn silage system can help them achieve their crop production goals through improvements in soil quality and pest management. Information provided to farmers through this research and outreach program allowed farmers to successfully establish cover crops through interseeding and provided benefits such as improved soil health and crop yields.

Cooperators

Click linked name(s) to expand
  • Richard Kersbergen (Educator and Researcher)
  • Caragh Fitzgerald (Educator and Researcher)
  • Kirsten Workman (Educator and Researcher)

Research

Hypothesis:

We proposed that changes in corn silage production practices and cover crop seeding opportunities could improve the establishment of interseeded cover crops.

This improved establishment will lead to greater cover crop biomass, which is known to reduce erosion, improve soil quality, water and nutrient management, weed control and, ultimately, corn silage yields.

We will specifically examine the effects of corn silage seeding rate, corn type (plant architecture), corn relative maturity rating, and interseeding timing on cover crop establishment. Treatments will be evaluated in small plots with on-station trials and across multiple environments with on-farm replicated strip trials.

Materials and methods:

2018 University Research Station Trials

Effect of corn architecture and population- Borderview Research Farm in Alburgh, VT

On 12-Jun, 2018, fixed ear MY87B10 and flex ear 2G161 Mycogen short season corn varieties, and fixed ear SW 4029 and flex ear SW 4010 Seedway long season corn varieties were planted at 28, 30, 32, 34, and 36,000 plants acre-1 in a randomized block design with three replicates. Each plot was 10’ x 20’ and consisted of four rows of corn spaced 30” apart. At planting, liquid starter fertilizer (9-18-9) was applied at a rate of 5 gal ac-1. Due to a field management error, the plots containing the short season varieties were replanted on 30-Jun. Cover crops were interseeded into the plots on 5-Jul using a 10’ Penn State interseeder. Beginning on 3-Jul, photosynthetic active radiation (PAR) levels penetrating through the corn canopy to ground level were recorded approximately weekly in all plots until harvest. PAR was measured using a LI-COR LI-191R Line Quantum Sensor equipped with a LI-1500 GPS enabled data logger. In each plot two measurements were taken, one above the corn canopy to capture the total available sunlight, and one under the canopy at approximately ground level in the center of the plot to capture light available to the cover crop. From these two readings percent infiltration of PAR was calculated by dividing the in-canopy reading by the outside reading. Corn was harvested 5-Oct. Yields were recorded using a wagon equipped with scales. An approximate one lb subsample from each plot was collected, weighed, and dried to determine dry matter content at harvest. The dried samples are still in the process of being ground and analyzed for silage quality. Post-harvest, ground cover from the cover crop was recorded using the Canopeo application. The cover crops were too small to collect biomass from at this location. Refer to Table 1 for a summary of cropping records for this trial and location.

Table 1. Summary of crop management at Borderview Research Farm, VT.

Location

 Borderview

Soil Preparation

Moldboard plow followed by disk and spike tooth harrow

Planting Date

12-Jun, short season plots replanted 30-Jun

Corn Varieties

2G161 (84 RM, flex)

MY87B10 (87 RM, fixed)

SW4010 (100 RM, flex)

SW4029 (100 RM, fixed)

Seeding Rates

(seeds acre-1)

28,000

30,000

32,000

34,000

36,000

Starter Fertilizer

5 gal ac-1 9-18-9 starter

Cover Crop

25 lbs ac-1

Annual ryegrass (70%)

Red clover (20%)

Tillage radish (10%)

Cover Crop Planting Date

5-Jul

Harvest Date

5-Oct

 

University Trial - Effect of corn architecture and interseed timing- Borderview Research Farm in Alburgh, VT

On 12-Jun, 2018,  fixed ear MY87B10 and flex ear 2G161 Mycogen short season corn varieties, and fixed ear SW 4029 and flex ear SW 4010 Seedway long season corn varieties were planted 34,000 seeds acre-1 in a randomized block design with four replicates. Each plot was 10’ x 20’ and consisted of four rows of corn spaced 30” apart. At planting liquid starter fertilizer (9-18-9) was applied at a rate of 5 gal ac-1. Due to a field management error, the plots containing the short season varieties were replanted on 30-Jun. Cover crops were interseeded into the plots at the V2, V4, and V6 growth stages using a 10’ Penn State interseeder. Beginning on 3-Jul, photosynthetic active radiation (PAR) levels penetrating through the corn canopy to ground level was recorded approximately weekly in all plots until right before harvest. PAR was measured using a LI-COR LI-191R Line Quantum Sensor equipped with a LI-1500 GPS enabled data logger. In each plot two readings were taken, one above the corn canopy to capture the total available sunlight, and one under the canopy at approximately ground level in the center of the plot to capture light available to the cover crop. From these two readings percent infiltration of PAR was calculated by dividing the in-canopy reading by the outside reading. Corn was harvested on 4-Oct. Yields were recorded using a wagon equipped with scales. An approximate one pound subsample from each plot was collected, weighed, and dried to determine dry matter content at harvest. The dried samples are still in the process of being ground and analyzed for silage quality. Post-harvest, ground cover from the cover crop was recorded using the Canopeo application. The cover crops were too small to collect biomass from at this location. Refer to Table 2 for a summary of cropping records for this trial and location.

Table 2. Summary of crop management at Borderview Research Farm, VT.

Location

 Borderview

Soil Preparation

Moldboard plow followed by disk and spike tooth harrow

Planting Date

12-Jun, short season plots replanted 30-Jun

Corn Varieties

2G161 (84 RM, flex)

MY87B10 (87 RM, fixed)

SW4010 (100 RM, flex)

SW4029 (100 RM, fixed)

Interseed Timings (corn growth stages)

V2

V4

V6

Pesticide Application

None

Cover Crop

25 lbs ac-1

Annual ryegrass (70%)

Red clover (20%)

Tillage radish (10%)

Cover Crop Planting Dates

2-Jul (V2)

5-Jul (V4)

30-Jul (V6)

Harvest Date

4-Oct

 

2018 On-Farm Trials

Effect of corn architecture, seeding rate, and hybrid - Smith Farm, VT

On 27-Jun, semi-flex ear MY87B10 and flex ear 2G161 Mycogen short season corn varieties were planted at 30,000 and 35,000 plants acre-1. At planting, RiseR (pop-up fertilizer) 7-17-3 was applied through the planter at 5 gallons acre-1.  One hundred lbs acre-1 urea fertilizer (46-0-0) was broadcast into corn just before the cover crop was interseeded.  There were a total of 24 plots, seven  replicates of both varieties and 35,000 plants acre-1 and five replicates of 30,000 plants acre-1.  Each plot was 7.5’ wide, running the length of the field, consisting of three rows of corn. A PSNT soil test was collected on 13-Aug which indicated the need for additional nitrogen.  However, no additional nitrogen fertilizer was applied.  Corn was hand harvested on 12-Oct.  See Table 3 for a summary of field management operations.

Table 3. Summary of crop management at Smith Farm, VT.

Field Operator

 Smith

Planting Date

27-Jun

Corn Variety

2G161 (84 RM)

MY87B1(87 RM)

Seeding Rate

(seeds acre-1)

30,000/35,000

Fertilizer Applied

5 gal @ 7-17-3 (27-Jun)

100 lbs @ 46-0-0 (31-Jul)

Herbicide Application

Corvus @ 4 oz. acre-1

Aatrex @ 1 pt. acre-1

(7-Jul)

Pesticide Application

None

Cover Crop

25 lbs. acre-1

Annual rye (70%), clover (20%), radish (10%)

Cover Crop Planting Date

2-Aug

Harvest Date

12-Oct

 

Effect of corn architecture, seeding rate, and hybrid - Machia Farm, VT

 On 23-May, semi-flex ear MY87B10 and flex ear 2G161 Mycogen short season corn varieties were planted at 30,000 and 35,000 plants acre-1 ­in a side by side comparison of no-till and conventional farming practices at the Machia Farm in St. Albans Bay, VT. Nytan was applied at a rate of six gallons acre-1 at time of planting.  There were a total of 3-row 24 plots, three replicates of each variety at each seeding rate.  Due to a planter issue, the conventional field had four replicates of both varieties and 35,000 plants acre-1 and only two replicates of 30,000 plants acre-1.  On 7-May, prior to planting, soil health samples were taken in accordance standards for and submitted for analysis to Cornell’s Comprehensive Assessment of Soil. Corn populations were recorded at harvest on 5-Sep. Refer to Table 4 for a summary of cropping records.                        

Table 4. Summary of crop management at Machia Farm, VT.

Field Operator

 Machia

Planting Date

23-May

Corn Variety

2G161 (84 RM)

MY87B1(87 RM)

Seeding Rate

(seeds acre-1)

30,000 & 35,000

Cover Crop

25 lbs

Annual rye (70%), clover (20%), radish (10%)

Cover Crop Planting Date

13-Jun

Corn Harvest Date

5-Sep

 

 Effect of corn seeding rate on cover crop growth - Barker Farm, ME

On 19-May, short season corn was seeded at 28,000 and 32,000 plants acre-1. There were a total of 16 plots, 5 replicates of each seeding rate. Cover crops were interseeded on 24-Jun (V4) using a farmer-modified Spray Coupe (Table 5). Light meter readings were recorded on 26-Jun, 4-Jul, 11-Jul, 19-Jul, 30-Jul, 10-Aug, and 8-Sep. Corn was sampled on 9-Sep for analysis.                                 

Table 5. Summary of crop management at Barker Farm, ME.

Field Operator

Barker Farm

Planting Date

19-May

Seeding Rate

(seeds acre-1)

28,000/32,000

Cover Crop

15 lbs. acre-1

Annual rye (72%), clover (10%), turnip (10%) radish (7%)

Cover Crop Planting Date

24-Jun

Harvest Date

8-Sep

 

  Effect of corn plant architecture on cover crop growth - Wright Farm, ME

In mid-May, short season corn varieties Mycogen MY87B10 and 2G161 were planted as field trials (Table 6).  Cover crops were interseeded in late June. Light meter readings were recorded at both locations on 7-Jul, 12-Jul, 20-Jul, 30-Jul, 10-Aug, and 7-Sep. Corn was sampled on 7-Sep for analysis. At Wright Place Farm, cover crop ground cover was measured by Canopeo and samples were collected for dry matter. 

Table 6. Summary of crop management at Wright Farm, ME.

Field Operator

Wright Place Farm

Planting Date

24-May

Corn Variety

Mycogen MY87B10/ Mycogen 2G161

Cover Crop

15 lbs. acre-1

Annual rye (72%), clover (10%), turnip (10%) radish (7%)

Cover Crop Planting Date

25-Jun

Harvest Date

7-Sep

 

Effect of interseeding timing on cover crop growth - Barker Farm, ME

Prior to cover crop planting, herbicides Roundup and Banvel were applied.  Cover crops in this field trial were planted on 26-Jun (V4), 7-Jul (V5-6), 9-Jul (V6), and 17-Jul (V7) (Table 7). Light meter readings were recorded on 26-Jun, 4-Jul, 11-Jul, 19-Jul, 30-Jul, 10-Aug, and 8-Sep. Corn was hand-sampled on 8-Sep for analysis. The cover crop ground cover was measured by Canopeo and samples collected for biomass measurements on 25-Sept.                             

Table 7. Summary of crop management at Barker Farm, ME.

Field Operator

Barker Farm

Cover Crop

15 lbs. acre-1

Annual rye (72%), clover (10%), turnip (10%) radish (7%)

Cover Crop Planting Date

25-Jun (V4)

7-Jul (V5-6)

9-Jul (V6)

17-Jul (V7)

Harvest Date

8-Sep

 

Effect of corn hybrid on cover crop growth - Misty Meadow Farm, ME

On 22-May, 43 corn hybrids were planted in three replicates of 15’X 75’ plots (Table 8).  On 25-Jun, the cover crop was planted. Prior to cover crop planting, herbicides Roundup and Banvel were applied.  Cover crops in this field trial were planted on 26-Jun (V4), 7-Jul (V5-6), 9-Jul (V6), and 17-Jul (V7). Light meter readings were planned to be measured during the trial.  There was no light interception during the first reading and it was impossible to access the plots in subsequent attempts due to size of the trial.  At the end of the season, cover crop stands were very irregular within each plot and varied greatly from plot to plot.  For this reason, cover crop measurements were not taken.                              

Table 8. Summary of crop management at Misty Meadow Farm, ME.

Field Operator

Misty Meadow Farm

Planting Date

22-May

Corn Variety

43 hybrids

Fertilizer Applied

125 lbs acre-1 N as urea

(preplant)

Manure Application

5,000 gal acre-1

Cover Crop

15 lbs. acre-1

Annual rye (72%), clover (10%), turnip (10%) radish (7%)

Cover Crop Planting Date

25-Jun

Harvest Date

13-Sep

   

 

2019 University Research Station Trials

Effect of corn architecture and population- Borderview Research Farm, Alburgh, VT

On 23-May, semi-flex ear, vertical-leaf architecture TMF2L395 and flex ear, horizontal-leaf architecture TMF2Q419 Mycogen short season corn varieties, and fixed ear, vertical-leaf architecture SW 4029 and flex ear, horizontal-leaf architecture SW 4010 Seedway long season corn varieties were planted at 28, 30, 32, 34, and 36,000 plants acre-1 in a randomized block design with four replicates. Each plot was 10’ x 20’ and consisted of four rows of corn spaced 30” apart. At planting liquid starter fertilizer (9-18-9) was applied at a rate of 5 gal ac-1. Cover crops were interseeded into the plots on 1-Jul using a 10’ Penn State interseeder. Beginning 2-Jul, photosynthetic active radiation (PAR) levels penetrating through the corn canopy to ground level was recorded approximately weekly in all plots until right before harvest. PAR was measured using a LI-COR LI-191R Line Quantum Sensor equipped with a LI-1500 GPS enabled data logger. In each plot two readings were taken, one above the corn canopy to capture the total available sunlight, and one under the canopy at approximately ground level in the center of the plot to capture light available to the cover crop. From these two readings percent infiltration of PAR was calculated by dividing the in-canopy reading by the outside reading. Short season varieties were harvested on 27-Sep and long season varieties on 9-Oct. Yields were recorded using a wagon equipped with scales. An approximate 1 lb subsample from each plot was collected, weighed, and dried to determine dry matter content at harvest. Post-harvest, ground cover from the cover crop was recorded using the Canopeo application on 6-Nov. The cover crops were too small to collect biomass from at this location. Refer to Table 9 for a summary of cropping records for this trial and location. 

Table 9. Summary of crop management at Borderview Research Farm, VT.

Location

Borderview

Planting Date

5/23/2019

Corn Varieties

TMF2Q419 (96 RM, semi-flex, horizontal)

TMF2L395 (94 RM, semi-flex, vertical)

SW4010 (100 RM, flex, horizontal)

SW4029 (100 RM, fixed, vertical)

Seeding Rates

(seeds acre-1)

28,000

30,000

32,000

34,000

36,000

Cover Crop

25 lbs ac-1

Annual ryegrass (70%)

Red clover (20%)

Tillage radish (10%)

Cover Crop Planting Date

7/1/2019

Harvest Dates

9/27/2019 (short RMs)

10/9/2019 (long RMs)

 

Effect of corn architecture and interseed timing- Borderview Research Farm, Alburgh, VT

On 23-May, fixed ear TMF2L395 and flex ear TMF2Q419 Mycogen short season corn varieties, and fixed ear SW 4029 and flex ear SW 4010 Seedway long season corn varieties were planted at 34,000 seeds acre-1 in a randomized block design with four replicates. Each plot was 10’ x 20’ and consisted of four rows of corn spaced 30” apart. At planting liquid starter fertilizer (9-18-9) was applied at a rate of 5 gal ac-1. Cover crops were interseeded into the plots at the V2, V4, and V6 growth stages using a 10’ Penn State interseeder. Beginning 19-Jun, PAR levels penetrating through the corn canopy to ground level was recorded approximately weekly in all plots until right before harvest. PAR was measured using a LI-COR LI-191R Line Quantum Sensor equipped with a LI-1500 GPS enabled data logger. In each plot two readings were taken, one above the corn canopy to capture the total available sunlight, and one under the canopy at approximately ground level in the center of the plot to capture light available to the cover crop. From these two readings percent infiltration of PAR was calculated by dividing the in-canopy reading by the outside reading. Short season varieties were harvested on 23-Sep and long season varieties were harvested on 10-Oct. Yields were recorded using a wagon equipped with scales. An approximate one pound subsample from each plot was collected, weighed, and dried to determine dry matter content at harvest. Post-harvest, plots were too weedy to capture ground cover from the cover crop as was measured in the population trial. Refer to Table 10 for a summary of cropping records for this trial and location. 

Table 10. Summary of crop management at Borderview Research Farm, VT.

Location

Borderview

Planting Date

23-May

Corn Varieties

TMF2Q419 (96 RM, semi-flex, horizontal)

TMF2L395 (94 RM, semi-flex, vertical)

SW4010 (100 RM, flex, horizontal)

SW4029 (100 RM, fixed, vertical)

Interseed Timings (corn growth stages)

V2

V4

V6

Cover Crop

25 lbs ac-1

Annual ryegrass (70%)

Red clover (20%)

Tillage radish (10%)

Cover Crop Planting Dates

6-17-18 (V2)

6-24-18 (V4)

7-1-18 (V6)

Harvest Dates

9/23/2019 (short RMs)

10/10/2019 (long RMs)

2019 On-Farm Trials

Effect of corn architecture, seeding rate, and hybrid - Machia Farm, VT

On 30-May, horizontal-leaf architecture TMF2Q419 and vertical-leaf architecture TMF2L395 Mycogen short season corn varieties were planted at 30,000 and 35,000 plants acre-1 ­. Nytan was applied at a rate of five gallons acre-1 at time of planting.  There were a total of 3-row 24 plots, three replicates of each variety at each seeding rate.  PSNT samples were taken on 1-Jul.  No sidedress nitrogen was added. Corn populations were recorded at harvest on 30-Sep. Refer to Table 11 for a summary of cropping records.
                      

Table 11. Summary of crop management at Machia Farm, VT.

Field Operator

 Machia

Planting Date

30-May

Corn Variety

TMF2Q419 (96 RM, semi-flex, horizontal)

TMF2L395 (94 RM, semi-flex, vertical)

Seeding Rate

(seeds acre-1)

30,000/35,000

Cover Crop

25 lbs

Annual rye (70%), clover (20%), radish (10%)

Cover Crop Planting Date

28-Jun

Harvest Date

30-Sep

 

Effect of corn architecture, seeding rate, and hybrid - Foster Farm, VT

 On June 27th, vertical-leaf architecture TMF2L395 and horizontal-leaf architecture TMF2Q419 Mycogen moderate length season corn hybrids were planted at 30,000 and 35,000 plants acre-1. UAN (Urea-ammonium nitrate) 32-0-0 was applied through the planter at 10 gallons acre-1. 200 pounds acre-1 Urea (46-0-0) was applied as side dress in late July.  There were a total of 12 6-row, 30-inch plots that were 515-feet in length.  This was comprised of three replicates of each hybrid at 30,000 plants acre-1 and 35,000 plants acre-1 (Table 12). Cover crop was interseeded into all plots on July 22, 2019 with an interseeder drill.  A mixture of 73.43% Annual Ryegrass/19.99% medium red clover/4.98% forage radish by weight was seeded at 35 pounds acre-1 , which equaled a pure live seed rate of 31 pounds acre-1  Cover crop had good germination of all species, and grew well throughout the season. Corn was hand harvested on October 10th, 2019 to match the farmer’s harvest schedule. Cover crop establishment was measured by collecting percent cover and biomass samples at harvest and three weeks post-harvest on all plots.                       

Table 12. Summary of crop management at Foster Farm, VT.

Field Operator

 Foster

Soil Preparation

No-Till

Winter Rye Cover Crop rolled/crimped after planting

Planting Conditions

wet

Planting Date

06/20/2019

Corn Variety

TMF2L395 (94 RM) - vertical

TMF2Q419 (96 RM) - horizontal

Seeding Rate

(seeds acre-1)

30,000/35,000

Pesticide Application

None

Cover Crop

35 lbs. acre-1

Annual rye (73%), clover (20%), radish (5%)

Total Pure Live Seed rate = 31 lbs  acre-1

Cover Crop Planting Date

07/22/2019

Harvest Date

10/10/2019

On June 27th, vertical-leaf architecture TMF2L395 and horizontal-leaf architecture TMF2Q419 Mycogen moderate length season corn hybrids were planted at 30,000 and 35,000 plants acre-1. UAN (Urea-ammonium nitrate) 32-0-0 was applied through the planter at 10 gallons acre-1. 200 pounds acre-1 Urea (46-0-0) was applied as side dress in late July.  There were a total of 12 6-row, 30-inch plots that were 515-feet in length.  This was comprised of three replicates of each hybrid at 30,000 plants acre-1 and 35,000 plants acre-1 (Table 12). Cover crop was interseeded into all plots on July 22, 2019 with an interseeder drill.  A mixture of 73.43% Annual Ryegrass/19.99% medium red clover/4.98% forage radish by weight was seeded at 35 pounds acre-1 , which equaled a pure live seed rate of 31 pounds acre-1  Cover crop had good germination of all species, and grew well throughout the season. Corn was hand harvested on October 10th, 2019 to match the farmer’s harvest schedule. Cover crop establishment was measured by collecting percent cover and biomass samples at harvest and three weeks post-harvest on all plots.

Effect of corn seeding rate on cover crop growth - Leeds Farm, ME

On 12-Jul, short season corn was seeded at 28,000 and 32,000 plants acre-1. There were a total of 16 plots, 5 replicates of each seeding rate. Cover crops were interseeded on 22-Jul using a farmer-modified Spray Coupe. Light meter readings were recorded on 26-Jun, 4-Jul, 11-Jul, 19-Jul, 30-Jul, 10-Aug, and 8-Sep. Corn was sampled on 9-Sep for analysis (Table 13). A wet spring resulted in extremely late planting and the growing season was very compressed.  By the time a suitable waiting period passed after herbicide application, there was only time for one overseeding before the corn was too tall (>6’ tall) for the equipment. With only one overseeding date and no comparisons to be made, yield data was not collected on this plot in 2019.  After harvest, no significant cover crop could be found in the plot. 

Table 13. Summary of crop management at Leed Farm, ME.

Field Operator

Leed Farm

Planting Date

12-Jul

Seeding Rate

(seeds acre-1)

28,000/32,000

Pesticide Application

None

Cover Crop

15 lbs. acre-1

Annual rye (80%), medium red clover (10%), purple top turnip (5%) Eco-till radish (5%)

Cover Crop Planting Date

22-Jul

 Effect of corn hybrid on cover crop growth - Misty Meadow Farm, ME

On 3-June, 39 corn hybrids were planted in three replicates of 15’X 75’ plots (Table 14). On 10-July, the cover crop was planted. Prior to cover crop planting, herbicides Verdict and Spirit were applied. Cover crop emergence was limited and spotty under the canopy. There was little cover visible after harvest.  It is worth noting that one side of the field was chopped in mid-August in advance of the Farm Days event.  Where the corn was removed early, there was a substantial cover crop stand.                             

Table 14. Summary of crop management at Misty Meadow Farm, ME.

Field Operator

Misty Meadow Farm

Planting Date

3-June

Corn Variety

39 hybrids

Seeding Rate

(seeds acre-1)

32,000

Cover Crop

15 lbs. acre-1

Annual ryegrass (80%), medium red clover (10%), purple-top turnip (5%), and Eco-till radish (5%). 

Cover Crop Planting Date

10-Jul

Harvest Date

16-Oct

 

2020 University Research Station Trials

The field trials were conducted at Borderview Research Farm in Alburgh, VT (Tables 15 and 16). Trial 1 evaluated the impact of corn variety and population on cover crop establishment and corn yields. Trial 2 evaluated the impact interseed timing on cover crop establishment and corn yields. All plots were 10’ x 20’, consisting of four rows of corn spaced 30” apart, and replicated three times.

The experimental design for Trial 1 was a randomized complete block with split plot design. Main plots were corn population (28,000, 34,000, and 38,000 plants ac-1) and split plots were corn varieties. The plots were interseeded with a cover crop mixture of annual ryegrass (60%), tillage radish (10%) and red clover (30%) when the corn reached the V6 growth stage. In Trial 2, the experimental design was a randomized complete block design where treatments were interseed timing (V2, V4, and V6 corn growth stages).

Corn was planted on 13-May and 6-May in Trial 1 and 2 respectively. In Trial 1, plots were originally seeded at 40,000 seeds ac-1 and thinned to the appropriate treatment populations on 9-Jun. The amount of PAR reaching the ground under the corn canopy was measured using a LI-COR LI-191R line quantum light sensor equipped with a LI-1500 data logger. Light was measured approximately weekly from the time of interseeding through August. To understand how much the corn canopy was obstructing the total available light, a light measurement was taken outside of the corn canopy and then under the corn canopy in the center of each plot. The data were then used to calculate the percent of light infiltrating the corn canopy. Corn was harvested using a John Deere 2-row corn chopper and collected in a wagon fitted with scales to weigh the yield of each plot. An approximate one pound subsample was collected, weighed, dried, and weighed again to determine dry matter content and calculate yield. The samples from Trial 1 were then ground to 2mm using a Wiley sample mill and then to 1mm using a cyclone sample mill (UDY Corporation). The samples were analyzed for forage quality via Near Infrared Reflectance Spectroscopy at the UVM Cereal Grain Testing Laboratory (Burlington, VT) using a FOSS DS2500 NIRS. No quality analyses were conducted on the corn from Trial 2.

Following harvest, on 20-Oct, ground cover was measured in Trial 1 by processing photographs using the Canopeo© smartphone application. On 27-Oct, cover crop biomass was measured by collecting biomass within a 0.25m2 area in each plot in the trial. Samples were weighed and dried to determine dry matter content and calculate yield. The samples were also ground using the same procedures for the corn samples and analyzed for %C, %N, and C:N ratio at the University of Vermont Agricultural and Environmental Testing Laboratory (Burlington, Vermont). In Trial 2, cover crop establishment and growth post-harvest was minimal with higher weed incidence than in Trial 1. In order to capture the ground cover contributed by cover crops and weeds separately, ground cover in this trial was measured using the beaded string method on 28-Sep. Cover crops were too small to collect biomass samples and therefore, yield and quality is not reported.

Table 15. Summary of crop management for population by variety trial at Borderview Research Farm, VT.

Location

Borderview 

Soil type

Cabot extremely stony fine sandy loam

Corn variety treatments

(relative maturity)

B94T73R (94RM)

B94T73SX (94 RM)

B97T04SXE (97 RM)

CP3499VT2P (94 RM)

P9608R (96 RM)

SW3768 (95 RM)

SW4010 (100 RM)

38N85 (92 RM)

9070AM (90 RM)

Corn population treatments

(plants ac-1)

28,000

34,000

38,000

13-May

Corn planting date

Cover crop mixture

25 lbs ac-1

Annual ryegrass (60%)

Red clover (30%)

Tillage radish (10%)

Cover crop planting date

22-Jun

Harvest date

17-Sep

 

Table 16. Summary of crop management for the interseeding timing trial at Borderview Research Farm, VT.

Location

Borderview 

Soil type

Cabot extremely stony fine sandy loam

Interseed timing treatments

(dates of interseeding)

V2 (2-Jun)

V4 (10-Jun)

V6 (22-Jun)

Corn planting date

6-May

Cover crop mixture

25 lbs ac-1

Annual ryegrass (60%)

Red clover (30%)

Tillage radish (10%)

Harvest date

9-Sep

 

Statistical Analysis

Data were analyzed using mixed model analysis using the mixed procedure of SAS (SAS Institute, 1999).  Replications in the trial were treated as random effects and treatments were treated as fixed. Mean comparisons were made using the Tukey-Kramer adjustment procedure when the F-test was considered significant (p<0.10). 

 

Impact of Modifying Corn Practices on Cover Crop Interseeding Biomass, Soil Health, and Corn Yields

In collaboration with the Vermont Cover Crop Cost Share Program, 30 farms from northern, VT were enrolled in our SARE research/education grant. Working with the Vermont Agency of Agriculture and collaborating farmers we were able to collect soil health samples prior to cover cropping.  The project team interacted with the collaborating farms to select corn practices, herbicides, cover crop species. Interseeding equipment was also made available to collaborating farms. The Cover Crop Cost Share Program paid for the cover cropping and other cost share dollars paid for soil sampling. It was an excellent collaboration that allowed our team to not only expand the adoption of strategies to enhance interseeding but also to track soil and yield data across a large number of farms. This information was used to help verify the performance target. Soil samples were sent to the Cornell Soil Health Laboratory to collect a baseline (2018) and a final soil health assessment in the fall of 2020. Cover crop biomass and corn yields were collected by the project team  using both hand harvest methods, portable truck scales, and farmer harvest units. Figure 1 shows the collaborating farm locations.

Research results and discussion:

2018 University Research Station Trials

Effect of corn architecture and population- Borderview Research Farm in Alburgh, VT

Impact of Population

Corn population impacted corn yield and cover crop ground cover. Corn yields ranged from 14.1 to 17.9 tons ac-1 (Figure 2 ) but were not statistically different from one another. Yields generally increased with increasing seeding rate until 32,000 seeds ac-1 after which yields declined slightly. Ground cover followed the opposite trend decreasing as populations increased.

Cover crop ground cover is one indicator of cover crop establishment success as the better the cover crop establishes and fills in, the less bare ground should be exposed through its canopy. We hypothesized that lower light availability under dense corn canopies will reduce cover crop establishment success and would therefore be reflected in lower ground cover. However, the populations allowed similar amounts of light to infiltrate the canopy throughout the season (Figure 3). Despite slightly lower light availability within the relatively high yielding corn crop at the 32,000 seeds ac-1 treatment, the cover crop was still able to maintain over 30% ground cover post-harvest.

When corn hybrids were separated by relative maturity, corn seeding rate significantly impacted cover crop ground cover for long season hybrids (Figure 4 ). The two highest seeding rates resulted in cover crop ground cover levels below 30% whereas the other seeding rates all supported >35% ground cover.

In general, the canopy closed within two weeks of the cover crop being interseeded at which point PAR infiltration was reduced to by 65-80%. The sharp growth of the corn canopy and subsequent decline in light availability was likely attributed to a 0.70” rain event on 17-Jul, the first substantial rainfall in 11 days. The amount of time until canopy closure was likely influenced by these dry conditions and may differ in other years. This period of drought also coincided with the interseeding of the cover crop and likely slowed its emergence. This situation exemplifies the challenge with managing interseeded cover crops in this region.

Impact of Ear Type

Corn hybrids are typically characterized as “flex”, “semi-flex”, or “fixed” ear types. Flex ear hybrids are more cost effective when planted at lower seeding rates as they have the ability to adjust corn ear size relative to plant population to remain high yielding despite fewer plants. Fixed ear types, on the other hand, have been bred to remain consistent in ear size regardless of plant population and are therefore become more profitable as populations are increased. These hybrid types also tend to differ in plant architecture or growth habit. Fixed ear hybrids tend to have a more upright leaf structure as they are better suited to the compact nature of high seeding rates. Therefore, we hypothesized that ear type would impact the corn population that would support a high yielding corn crop and successful interseeded cover crop. We found that ear type did not significantly impact corn yield across populations (Figure 5 ).

Although we did see a divergence of about 2 tons ac-1 in the fixed ear hybrid yields above 32,000 seeds ac-1, we did not observe a difference at low populations (Figure 6). Furthermore, in terms of cover crop ground cover, the opposite trend was observed than expected with the fixed ear hybrid plots outperforming flex ear hybrid plots, in terms of cover crop ground cover, at low populations while the opposite occurs at higher populations. None of these differences were statistically significant.

Impact of Hybrid Relative Maturity

Corn hybrids are also characterized by the length of the growing season required for the hybrid to reach physiological maturity. Long season corn varieties, or those with higher relative maturities, are generally regarded as having higher yield potentials as they are able to maximize resources over the longer growing period. This trend was observed in this trial as the long season hybrids produced yields approximately 3 tons ac-1 higher than season hybrids (Figure 7 ). However, in northern regions where the growing season is relatively short and is often shortened further due to unfavorable weather, short season varieties are being promoted as potential tools to be more resilient to unpredictable weather. These varieties likely have faster growth rates than longer season varieties as they are bred to mature in shorter periods of time. The short season hybrids did reach significantly lower dry matter contents at harvest compared to long season hybrids, with the short season reaching 36.4% and the long reaching 39.0%. In this trial, however, light infiltration remained higher for longer in short season variety plots (Figure 8 ).

Light infiltration was approximately 10% higher in short season plots two weeks after corn was planted and approximately 20% higher after three weeks. As mentioned previously, the cover crop was interseeded on 12-Jul but rainfall was not experienced until 17-Jul. The cover crop therefore likely only had about 10 days to germinate and establish before the corn canopy significantly reduced the available light. Unfortunately, we were unable to collect cover crop ground cover data from the short season varieties to see whether cover crops established better where yields were lower.

Corn quality also differed slightly across relative maturities (Table 17). Crude protein (CP) was slightly higher in short season varieties but long season varieties had lower acid detergent fiber (ADF) and higher starch. Due to the significant difference in yields, milk per acre was higher in long season varieties. All other measures did not differ statistically between relative maturity groups.

Table 17. Corn quality by relative maturity, Borderview Farm, VT.

Relative maturity

DM

CP

ADF

NDF

Ash

Starch

TDN

30-hr NDFD

NEL

Milk

 

% of DM

% of NDF

Mcal lb-1

lbs ton-1

lbs ac-1

Long Season

39.0

8.61

22.0

38.0

2.05

34.4

69.4

45.1

0.684

3165

20027

Short Season

36.4

8.89

23.0

38.9

2.32

31.6

69.2

44.4

0.682

3155

16481

LSD (p = 0.10)

1.20

0.259

0.624

NS

NS

1.93

NS

NS

NS

NS

2124

Trial mean

37.7

8.71

22.5

38.5

2.19

33

69.3

44.7

0.683

3160

18254

Treatments in bold were the top performer for that category.

‡LSD; least significant difference at the p=0.10 level.

NS- not statistically significant.

Timing Trial- Impact of Cover Crop Interseed Timing, Borderview Farm, Alburgh, VT

Deciding when to interseed a cover crop is challenging. On one hand you want to allow the cover crop time to establish before the corn blocks the light, but on the other hand, you don’t want the cover crop to compete with the establishing corn for resources. Generally, corn can be interseeded anywhere from the V2 to V6 growth stage. After V6, most interseeding equipment is not tall enough, increasing the risk of damaging the corn crop. In this trial, as interseeding was delayed to the V6 growth stage, cover crop success, indicated by post-harvest ground cover, decreased (Figure 9). However, ground cover was <50% for all interseed timing treatments. Corn yields were not significantly impacted by timing of interseeding. In addition, corn quality was not impacted by timing of interseeding (Table 18). 

  Table 18. Corn quality by interseed timing, Borderview Farm, VT.

Interseed timing

DM

CP

ADF

NDF

Ash

Starch

TDN

30-hr NDFD

NEL

Milk

% of DM

% of NDF

Mcal lb-1

lbs ton-1

lbs ac-1

V2

38.1

18.6

22.8

40.2

3.37

31.7

67.3

44.6

0.659

3004

19578

V4

37.8

19.6

23.1

40.6

3.72

30.4

66.7

44.0

0.654

2963

20264

V6

37.6

17.6

23.0

41.4

3.49

30.9

67.3

44.2

0.660

3007

18546

LSD (p = 0.10)

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

Trial mean

37.8

8.6

23.0

40.7

3.5

31.0

67.1

44.3

0.658

2991

19462

Treatments in bold were the top performer for that category.

‡LSD; least significant difference at the p=0.10 level.

NS- not statistically significant.

Light available at the time of interseeding varied dramatically across the timing treatments (Figure 10). The arrows indicate the date the corn was interseeded corresponding to the V2, V4, and V6 growth stages. At the V2 and V4 growth stages virtually none of the PAR was being obstructed by the corn canopy. However, by the time the corn reached the V6 stage, the canopy was already obstructing almost 70% of the light. That was reduced by an additional 20% by the following week where the level remained for much of the season. However, this did not appear to significantly impact cover crop establishment as post-harvest ground cover was approximately similar to that of the V4 seeded cover crop which had an additional few weeks to grow. However, it is also important to note that following the V2 and V4 interseedings, no rainfall was experienced for 12 days. Therefore, the cover crop may have not germinated as quickly, reducing the impact between the interseed timings.

Impact of Corn Ear Type

With fixed ear hybrids having generally a more upright leaf structure, we would expect better cover cropping success with a fixed ear hybrid over a flex ear hybrid. In this trial, we observed the highest cover crop success, indicated by post-harvest ground cover, from the fixed ear hybrids, however, this was only observed when interseeded at the V2 growth stage and was not statistically significant (Figure 11). Corn yield and quality parameters also did not differ across the ear types.

2018 On-Farm Trials

Effect of corn architecture, seeding rate, and hybrid 

 Corn Populations and Yield - Machia Farm, VT  

Plant populations in the lower seeding rate treatment were 3,000 plants ac-1 below the seeding rate and the plant populations in the higher seeding rate were 3,600 plants ac-1 below the seeding rate (Table 19).  However, this variation in plant population, regardless of hybrid or seeding rate did not significantly impact the yields. Yields ranged between 26.2 and 27.8 tons ac-1. Hybrid selection prove to have a bigger impact on yields with the flex ear variety yielding on average 1 ton per acre higher than the fix ear variety. 

Table 19. The impact of seeding rate and hybrid on corn silage yield, Machia Farm, VT. 

Hybrid

Seeding Rate

Plant Population

Yield 35% DM

 

plants ac-1

plants ac-1

tons ac-1

Flex ear

30,000

26,500

27.8b

Flex ear

35,000

30,500

27.4b

Fix ear

30,000

27,500

26.2a

Fix ear

35,000

32,250

26.3a

 

 

Average

26.9

The top performer for a category is highlighted in bold.

 

Cover crop germination was not uniform in mid-October. To more accurately capture cover crop establishment success, cover crop and weed populations were counted using the beaded string method, as opposed to randomly selecting locations to sample for biomass. On 17-Oct, populations were counted on five 10-foot lengths in each of the 24 plots.

Cover crop coverage was 14% greater in the lower seeding rate than the higher seeding rate (Table 20). This may be due to less competition for sun, moisture, and soil nutrients.  There was an equal amount of weeds at either rate.  There was an 8% higher cover crop establishment success in flex ear plots than fix ear plots.  Cover crop coverage was highest (38%) in the fixed ear with low seeding rate treatments. 

Table 20. Impact of corn population and variety on cover crop establishment, Machia Farm, VT.

Management

Cover Crop

Weeds

 

%

%

30,000 rate

38

2

35,000 rate

24

2

Flex ear

34

2

Fix ear

26

1

The top performer for a category is highlighted in bold.

 

Effect of corn architecture, seeding rate, and hybrid - Smith Farm

Overall, yields were most impacted by corn population (Table 21).  Late planting, heavy clay soil and dry weather combined for a low overall yield average of all plots of 13.9 tons acre-1.  At the higher seeding rates yields were 0.7 tons acre-1 higher with the fix ear variety.  At the lower seeding rate, yields were 0.6 tons acre-1 higher with the flex ear variety.

Table 21. Impact of corn variety and population on corn silage yield, Smith Farm, VT.

 

Hybrid

Seeding Rate

Plant Population @ V4±

Plant Population @ HarvestII

Yield 35% DM

 

plants ac-1

plants ac-1

plants ac-1

tons ac-1

Flex

30,000

27,533

27,800

12.9

Flex

35,000

30,762

32,667

14.6

Fix

30,000

28,333

28,000

12.3

Fix

35,000

32,095

34,667

15.3

 

 

 

Average

13.9

The top performer for a category is highlighted in bold.

± collected on 31-Jul, measured using 3 x 1/1000th acre population counts in each plot

Π collected on 12-Oct, measured by counting plants harvested using 1 x 1/1000th acre sample in each plot

 

Cover Crop Populations
Cover crop germination was fairly uniform, other than where there was heavier weed pressure in specific areas in individual plots (Image-1-Interseeding-Cover-Crops). All three species (annual ryegrass, radish, red clover) were observed to have germinated.  However, the red clover seemed to be the least successful overall.  Cover crop establishment was quantified during the corn growing season by using the Canopeo ‘fractional green canopy cover’ measurement using a smartphone app roughly every two weeks up until harvest.  Post-harvest weather quickly turned snowy and we were unable to capture a post-harvest measurement using this method.  To align with the other sites, we collected percent cover using the beaded string method, as opposed to randomly selecting locations to sample for biomass for our final measurement. On 20-Dec, populations were counted on three 10-foot lengths in each of the 24 plots.  Because of previous cold weather, weeds were not counted, and total cover generally went down as much of the cover crop had gone dormant and/or been winter-killed (radish).  However, dead cover crop residue was quantified at this sample date.

Overall, the Flex ear variety consistently had more cover throughout the season the than Fix ear variety (Table 22).  Early in the season, there was higher percent cover in the higher seeding rate treatments, with some catch up of cover crop in the lower seeding rate before harvest.  However, at the end of the season, there was negligible difference among corn seeding rate treatments of percent cover crop cover.

Table 22. Impact of plant population and variety on cover crop establishment, Smith Farm, VT.

Management

Cover Crop

% cover

 

 

8/13/18II

8/29/18 II

9/12/18 II

9/25/18 II

12/20/18±

30,000 rate

5.0

9.9

15.1

26.8

21.3

35,000 rate

5.2

12.9

12.2

18.7

23.3

Flex ear

5.1

13.1

14.7

26.8

23.9

Fix ear

5.0

9.7

11.6

15.9

20.6

Flex @ 30,000 rate

5.7

11.2

18.8

33.7

23.3

Flex ear @ 35,000 rate

4.7

14.5

11.8

23.4

24.3

Fix ear @ 30,000 rate

4.3

8.6

11.4

19.8

19.3

Fix ear @ 35,000 rate

5.6

10.5

11.8

14.0

21.4

The top performer for a category is highlighted in bold.

Π measured using Canopeo digital fractional green canopy cover measurement

± measured using beaded string method

2018 Maine On-Farm Trial Results

The timing trials at the ME sited consisted of four overseeding dates at approximately weekly intervals, starting 6/24.  Only the cover crop planted at the first seeding date (6/24, at V4) was successful.  We considered the following reasons for the failure of later seedings:

  1. Herbicides with low residual activity were used.  Even so, injury can sometimes occur.  However, since the initial seeding was successful, herbicide injury does not seem a likely cause. 
  2. Within four days of the first seeding, 0.71” of rain fell.  Within five days of the second seeding, 0.43” of rain fell.  Insufficient moisture would not seem to be a likely cause, given this rainfall. 
  3. We know, of course, that the amount of light penetrating the crop canopy will decline as the corn crop grows.   At the time of the first overseeding, 98% of the ambient light reached the ground between the corn rows.  By the second overseeding date one week later, only 62% of the light reached the ground.   By the third overseeding date (two weeks after the first), only 36% of light reached the ground between the corn rows.  Although we cannot be certain, we suspect that insufficient light was the reason for the failure of later interseedings.

The timing trial and the flex/semi-flex trial at the Barker Farm were the two trials with measurable cover crop after harvest.  Cover crop yield ranged from 1650 lbs dry matter per acre to 371 lbs dry matter per acre.  In all plots, the brassicas dominated the stand.  This was a particular concern to one cooperating farmer, who observed that the brassicas created slippery driving conditions for trucks during the silage harvest.  It also means that there would be few living plants the following spring, since the brassicas are not winter-hardy.  

2019 University Research Station Trials 

Effect of corn architecture and population- Borderview Research Farm in Alburgh, VT

The results from 2018 and 2019 were analyzed together to get a sense of how the treatments performed by each year and across the two years of the

Interactions

There were no statistically significant interactions between the main effects of corn population and corn ear type (Table 23). This indicates that corn varieties of different ear types responded similarly in terms of yield and quality parameters when planted at different populations.

Table 23. Interactions between the main effects of corn population and corn ear type, Borderview Farm, VT.

Main effects and interactions

Yield

CP

ADF

30-hr NDFD

Ash

Starch

TDN

NEL

Milk yield                  (lbs ton-1)

Milk yield (lbs ac-1)

Year

***

***

**

***

***

***

***

*

***

***

Corn population

*

NS

NS

NS

NS

NS

NS

NS

NS

*

Corn ear type

NS

***

NS

*

NS

NS

NS

NS

NS

NS

Population x ear type

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

Significant at the * 0.1 < p > 0.05; ** 0.05 < p > 0.01; *** p < 0.01

NS- Not statistically significant

 

Impact of Year

The two years of the trial performed differently in terms of corn yield and quality characteristics (Table 24). Yield varied dramatically between the two trial years with 2018 yields being almost 9 tons ac-1 higher than 2019. Crude protein (CP) differed by almost 1% as well. These were likely due to lower water and therefore nutrient availability in 2019 compared to 2018. The hot and dry weather also appears to have resulted in higher lignin content as the NDF digestibility (dndf) was considerably lower in 2019. Because of these yield and quality differences, 2018 would have produced more milk yield both on a per acre and per ton basis.

Table 24. The impact of year on the corn silage yield and quality by year, Borderview Farm, VT.

Year

Yield at 35% DM

CP

ADF

NDF

Ash

Fat

TDN

30hr-NDFD

NEL

Milk yield

 

tons ac-1

% DM

% NDF

Mcal lb-1

lbs ton-1

lbs ac-1

2018

25.2

8.74

22.5

38.5

4.13

3.06

69.3

58.2

0.683

3369

29712

2019

16.5

7.85

21.5

38.3

2.19

2.85

64.2

44.7

0.671

3158

18254

Level of significance

***

***

**

NS

***

***

NS

***

*

***

***

Trial Mean

21.5

8.24

21.9

38.4

3.3

2.95

66.4

52.4

0.676

3279

24801

Statistically significant at the * 0.1 < p > 0.05; ** 0.05 < p > 0.01; *** p < 0.01

NS- Not statistically significant

Impact of Population

Corn population significantly impacted yield (Figure 12). Statistically, no additional yield benefit was gained by attaining a plant population higher than 30,000 plants ac-1. Population did not impact corn silage quality.

By two weeks after cover crop interseeding, the corn canopy had significantly closed reducing 65-70% of the potential light infiltrating to the ground (Figure 13). Therefore, the newly planted cover crop had approximately 2-3 weeks from the time of seeding to germinate and establish prior to full canopy closure, in which very little light penetrated to the ground level for the remainder of the season. This demonstrates the challenge interseeding presents as any delay in seed germination or establishment (i.e. limited moisture, low vigor, etc.) significantly reduces the time available to the cover crop to properly establish increasing the chance of survival through the rest of the growing season.

Due to complications in the 2018 growing season, cover crop measures were not captured post corn silage harvest. However, these data are available for the 2019 growing season but were not statistically analyzed. Overall, ground cover from interseeded cover crops post corn silage harvest were very low averaging 4.69% with no obvious differences between populations. This will continue to be studied in the coming year.

Impact of Ear Type

Corn hybrids are typically characterized as “flex”, “semi-flex”, or “fixed” ear types. Flex ear hybrids are more cost effective when planted at lower seeding rates as they have the ability to adjust corn ear size relative to plant population to remain high yielding despite fewer plants. Fixed ear types, on the other hand, have been bred to remain consistent in ear size regardless of plant population and are therefore more profitable as populations are increased. These hybrid types also tend to differ in plant architecture or growth habit. Fixed ear hybrids tend to have a more upright leaf structure as they are better suited to the compact nature of high seeding rates. Therefore, we hypothesized that ear type would impact the corn population that would support a high yielding corn crop and successful interseeded cover crop.

Little difference in light infiltration was observed between corn ear types (Figure 14). Fixed ear varieties limited light infiltration slightly more than flex ear varieties, however, by 36 days after interseeding both had reduced light infiltration by approximately 90% and remained similar for the remainder of the trial. Overall, the ear type did not appear to significantly impact light infiltration through the corn canopy.

 

Corn ear type did not significantly impact yield and had a minor impact on corn silage quality parameters (Table 25). Crude protein was approximately 0.3% higher in flex ear varieties than the fixed ear varieties. This is to be expected as these varieties can change the size of ears formed depending on resources available (i.e. populations) which impacts the nutrient concentration in the end silage sample. However, the only other quality parameter that was significantly impacted by ear type was NDF digestibility at 30 hours. Again this was higher in flex ear varieties which we’d expect as there is likely a higher proportion of ear material compared to the less digestible fiber materials.

Table 25. The impact of corn ear type on silage yield and quality, Borderview Farm, VT. 

 

Yield at 35% DM

CP

ADF

NDF

Ash

Fat

TDN

30hr-NDFD

NEL

Milk yield

 

tons ac-1

% DM

% NDF

Mcal lb-1

lbs ton-1

lbs ac-1

Fixed

21.4

8.15

21.7

38.1

3.13

3.01

66.7

51.0

0.677

3257

24591

Flex

20.3

8.44

22.3

38.6

3.19

2.90

66.8

51.8

0.677

3270

23375

Level of significance

NS

***

NS

NS

NS

NS

NS

*

NS

NS

NS

Trial Mean

21.5

8.24

21.9

38.4

3.3

2.95

66.4

52.4

0.676

3279

24801

Significant at the * 0.1 < p > 0.05; *** p < 0.01

NS- Not statistically significant

In both years, cover crop establishment was poor and was difficult to obtain measurements on the minimal and spotty growth. Ground cover measurements could only be captured in some plots post corn harvest. Regardless of the treatment there was less than 5% ground cover provided by the cover crop in late-Oct.  More data will be collected in the coming year to better understand these implications.

Timing Trial- Impact of Cover Crop Interseed Timing, Corn Maturity, and Corn Ear Type at Borderview Farm, Alburgh, VT

Due to weed pressure limiting cover crop success in the trial area in 2019, cover crop establishment data were only available for 2018 and therefore, only data for that year are presented below.

2019 On-Farm Trials

Effect of corn architecture, seeding rate, and hybrid – Machia Farm, VT

Corn Populations and Yield

Plant populations in the lower seeding rate treatment were an average 4,083 plants ac-1 below the seeding rate and the plant populations in the higher seeding rate were an average of 5,167 plants ac-1 below the seeding rate. Plant populations were correlated with yield (i.e. the higher planting population had higher yields), regardless of variety. 

Yields ranged between 16.3 and 18.6 tons ac-1. The variety TMF2Q419 variety had the highest yield.  On average, TMF2Q419 variety had 0.8 tons ac-1 more than the TMF2L395 variety. The highest seeding rates had the highest yields (Table 26).

Table 26. Impact of plant populations and variety on corn silage yields at the Machia Farm, VT.

Hybrid

Seeding Rate

Plant Population

Yield 35% DM

 

plants ac-1

plants ac-1

tons ac-1

TMF2Q419

30,000

25,333

17.3

TMF2Q419

35,000

30,000

18.6

TMF2L395

30,000

24,667

16.1

TMF2L395

35,000

28,000

17.9

 

Average

27,000

17.5

The top performer for a category is highlighted in bold.

Cover Crop and Weed Populations

Cover crop germination was not uniform in early November. To more accurately capture cover crop establishment success, cover crop and weed populations were counted using the beaded string method, as opposed to randomly selecting locations to sample for biomass. On 4-Nov, populations were counted on five 10-foot lengths in each of the 24 plots.

Overall, cover crop populations were very low, covering between 10-13% of the field (Table 27). There were negligible or no differences in cover crop populations between the lower and higher corn seeding rate, and corn variety. Of the cover crop present, 76% was ryegrass, 24% radish, and 0% clover established. Percent cover of weeds averaged at 0% regardless of seeding rate, or corn variety. What few weeds were present were predominantly barnyard grass.

Table 27. Impact of seeding rate and corn variety on cover crop establishment at Machia Farm, VT. 

Management

Cover Crop

Weeds

 

%

%

30,000 rate

12

0

35,000 rate

12

0

TMF2Q419

11

0

TMF2L395

13

0

The top performer for a category is highlighted in bold.

Effect of corn architecture, seeding rate, and hybrid – Foster Farm, VT

Table 29 below shows the average yields at the different plant populations for each of the other variables. We did observe the expected trend of increasing yield with increasing population for fixed ear, vertical-leaf architecture varieties. Similarly, for flex ear, horizontal-leaf architecture varieties, we saw slightly higher yields at lower populations but the trend was less clear than with the fixed ear varieties. We also saw some difference between long and short season varieties with the long season varieties outperforming the short season varieties by an average of 0.8 tons-1. At populations above 32,000 plants ac-1, the fixed ear varieties outperformed the flex ear varieties by approximately 2-3 tons ac-1. At lower populations there was little difference between the two ear types.

Table 29. Impact of corn population on yields of corn varieties with different ear type and maturities at Foster Farm, VT.

Population

Average Yield at 35% DM (tons ac-1)

Overall

Fixed ear

Flex ear

Long season

Short season

28,000

23.6

23.6

23.5

23.9

23.2

30,000

24.5

23.8

25.2

24.2

24.8

32,000

25.1

26.2

24.1

24.7

25.5

34,000

25.6

27.0

23.9

26.1

25.2

36,000

27.3

29.0

25.6

27.7

26.9

The top performer for a category is highlighted in bold.

Effect of corn seeding rate on cover crop growth - Leeds Farm, ME

 A wet spring resulted in extremely late planting and the growing season was very compressed.  By the time a suitable waiting period passed after herbicide application, there was only time for one overseeding before the corn was too tall (>6’ tall) for the equipment. With only one overseeding date and no comparisons to be made, yield data was not collected on this plot in 2019.  After harvest, no significant cover crop could be found in the plot. 

 Effect of corn hybrid on cover crop growth - Misty Meadow Farm, ME

 Cover crop emergence was limited and spotty under the canopy. There was little cover visible after harvest.  It is worth noting that one side of the field was chopped in mid-August in advance of the Farm Days event.  Where the corn was removed early, there was a substantial cover crop stand come fall.    

2020 Research Station Trials

Effect of corn architecture and population- Borderview Research Farm in Alburgh, VT

Interactions

There was only one significant interaction between main effects (Table 30). A significant interaction between corn population and variety for cover crop dry matter yield indicates that the cover crop produced differing amounts of biomass when interseeded into the same corn variety planted at different populations. Figure 15 displays these differences. For most varieties, a lower seeding rate resulted in higher cover crop biomass; however, 38N85, 9070AM, and SW4010 did not follow this trend. These three varieties had similar or higher cover crop biomass when corn populations were higher. This may be due to plant architecture.  The lack of other significant interactions indicates that corn varieties responded similarly in terms of yield and quality parameters when planted at different populations.

Table 30. Significance of the main effects and main effect interactions, Borderview Farm, VT.

 

Population

Variety

Population x Variety

Population

***

NS

NS

Corn yield

**

***

NS

Fall ground cover

***

*

NS

Cover crop dry matter

*

NS

NS

Cover crop yield

***

NS

*

Corn dry matter

NS

***

NS

Corn crude protein

NS

***

NS

Corn ADF

NS

*

NS

Corn NDF

NS

*

NS

Corn NFC

NS

NS

NS

Corn lignin

NS

**

NS

Corn ash

NS

*

NS

Corn fat

NS

***

NS

Corn starch

NS

**

NS

Corn digestible starch

NS

***

NS

Corn WSC

NS

*

NS

Corn uNDF30

NS

***

NS

Corn uNDF120

NS

***

NS

Corn uNDF240

NS

***

NS

Corn TDN

NS

**

NS

Corn NEL

NS

**

NS

Corn VFA

NS

***

NS

Milk yield (lbs ton-1)

NS

**

NS

Milk yield (lbs ac-1)

**

***

NS

Significant at * 0.1 < p > 0.05; ** 0.05 < p > 0.01; *** p < 0.01

NS- Not statistically significant

Impact of Population

Corn population significantly impacted yield (Figure 16). Corn yields were significantly lower when populations of 28,000 and 34,000 plants ac-1 were used compared to 38,000. However, no additional yield benefit was observed from increasing from 28,000 to 34,000 plants ac-1. Population did not impact corn silage quality.

By two weeks after cover crop interseeding, the corn canopy had significantly closed reducing approximately 80% of the potential light infiltrating to the ground (Figure 17). Therefore, the newly planted cover crop had approximately 2-3 weeks from the time of seeding to germinate and establish prior to full canopy closure, in which very little light penetrated to the ground level for the remainder of the season. This demonstrates the challenge interseeding presents as any delay in seed germination or establishment (i.e. limited moisture, low vigor, etc.) significantly reduces the time available to the cover crop to properly establish increasing the chance of survival through the rest of the growing season.

Cover crop establishment also differed significantly by population (Table 31). Cover crops produced higher ground cover and biomass when interseeded into lower corn population stands. Ground cover significantly increased from 23.7% to 42% when populations were reduced below 34,000 plants ac-1. However, ground cover was not further impacted when populations increased from 34,000 to 38,000 plants ac-1. Similarly, cover crops produced over 300 lbs ac-1 more biomass when interseeded into corn at 28,000 plants ac-1 compared to corn at 34,000 plants ac-1. Cover crop biomass was not further impacted when populations were increased from 34,000 to 38,000 plants ac-1.

Table 31. Cover crop characteristics by corn silage population, Borderview Farm, VT.

Population

Ground cover

Cover crop dry matter

Cover crop dry matter yield

plants ac-1

%

%

lbs ac-1

28,000

42.0a†

10.9b

877a

34,000

23.7b

12.3a

551b

38,000

25.6b

11.9ab

678b

LSD (p=0.10)‡

5.67

1.13

134

Trial Mean

30.4

11.7

702

†Treatments that share a letter performed statistically similarly to one another.

‡LSD; least significant difference at the p=0.10 level.

Impact of variety

Variety significantly impacted corn yield and quality parameters (Tables 32 and 33). Corn silage yields ranged from 20.7 to 27.9 tons ac-1 with the top performing variety, B94T73R, yielding similarly to only one other variety, B94T73SX. Crude protein (CP) averaged 8.23% with the top performing variety, 38N85, containing 8.80% protein. Protein levels were decent despite dry conditions that could limit nitrogen availability and negatively impact protein levels. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents averaged 23.4% and 41.0% respectively. The lowest ADF and NDF contents were produced by variety B97T04SXE which had 21.1% ADF and 37.8% NDF. Four other varieties also performed statistically similarly to this variety in terms of both ADF and NDF content. Starch varied widely by variety ranging from 27.8% to 36.2% with the top performing variety, B97T04SXE, containing 3.6% more starch than the next highest variety. Water soluble carbohydrates (WSC) ranged from 5.99% to 7.81%. Total digestible nutrients (TDN) ranged from 61.9% to 64.6% with four other varieties performing similarly to the top performer. uNDF240 is the portion of the NDF fiber that remains undigested after 240 hours of exposure to rumen fluid. uNDF240 ranged from 10.2% to 12.8%. Net energy of lactation (Nel) ranged from 0.625 to 0.679 Mcal lb-1.

 

Table 32. Corn silage quality parameters by variety.

Variety

Yield at 35% dry matter

CP

ADF

NDF

Lignin

Ash

Fat

Starch

WSC

TDN

uNDF240

Nel

 

tons ac-1

% of DM

% of NDF

Mcal lb-1

B94T73R

27.9

8.01

24.8

42.7

3.13

4.55

2.99*

29.7

7.21*

63.2

12.2

0.647

B94T73SX

25.6*

8.06

26.0

44.5

3.28

4.83

2.66

27.8

6.76

61.9

12.8

0.625

B97T04SXE

24.2

8.19

21.1

37.8

2.73

4.11

3.25

36.2

5.99

64.6

10.2

0.679

CP3499VT2P

23.6

8.12

24.7

42.3

3.01*

4.75

2.87

30.4

6.83

62.8

11.7

0.641

P9608R

23.1

8.39

23.0*

40.1*

2.95*

4.61

3.20*

32.6*

6.59

63.8*

10.5*

0.664*

SW3768

23.2

8.47*

22.6*

39.8*

2.83*

4.87

3.10*

31.1

7.81

64.1*

11.0*

0.665*

SW4010

21.6

8.04

24.2

42.1

2.98*

4.85

2.66

30.5

6.93

62.8

12.0

0.641

38N85

20.7

8.80

21.7*

38.7*

2.79*

4.56

3.20*

32.3

6.93

64.2*

10.6*

0.671*

9070AM

23.3

7.94

22.9*

40.8*

2.82*

4.56

2.86

32.3

7.32*

63.7*

11.5

0.659*

LSD (p=0.10)

2.30

0.374

2.66

3.62

0.289

0.401

0.286

3.78

0.859

1.32

1.06

0.026

Trial Mean

23.7

8.23

23.4

41.0

2.95

4.63

2.98

31.4

6.93

63.4

11.4

0.655

* Varieties with an asterisk performed statistically similarly to the top performer in bold

‡LSD; least significant difference at the p=0.10 level.

Table 33. Predicted milk yield by variety.

Variety

Milk yield

 

lbs ton-1

lbs ac-1

B94T73R

3275

31808

B94T73SX

3175

28534

B97T04SXE

3405

28935

CP3499VT2P

3267

27015

P9608R

3359*

27125

SW3768

3369*

27366

SW4010

3238

24617

38N85

3402*

24599

9070AM

3298*

26843

LSD (p=0.10)

111

2756

Trial Mean

3310

27427

* Varieties with an asterisk performed statistically similar to the top performer in bold.

‡LSD; least significant difference at the p=0.10 level.

Post-harvest ground cover was also significantly impacted by corn variety, however, cover crop biomass was not (Table 34). Ground cover ranged from 20.2% in plots with variety CP3499VT2P to 38.4% in plots with variety SW3768. Interestingly, high corn yield was not clearly associated with lower ground cover. For example, the second highest yielding variety, B94T73SX, had a statistically similar level of ground cover as variety SW3768 which had the highest ground cover but yielded almost 2.5 tons ac-1 less than B94T73SX. This is important as it demonstrates that interseeding cover crops can be successful without compromising the yield of the corn crop (Figure 18).

 

Table 34. Cover crop characteristics by variety.

Variety

Ground cover

Cover crop dry matter yield

 

%

lbs ac-1

B94T73R

26.5bcd

805

B94T73SX

31.1abc

658

B97T04SXE

24.7cd

560

CP3499VT2P

20.2d

557

P9608R

36.0ab

717

SW3768

38.4a

900

SW4010

29.3abcd

652

38N85

32.7abc

728

9070AM

35.0ab

741

LSD (p=0.10)

9.82

NS

Trial Mean

30.4

702

†Treatments that share a letter performed statistically similarly to one another.

‡LSD; least significant difference at the p=0.10 level.

 

Effect of corn architecture and interseed timing- Borderview Research Farm, Alburgh, VT

Deciding when to interseed a cover crop is challenging. On one hand you want to allow the cover crop time to establish before the corn blocks the light, but on the other hand, you don’t want the cover crop to compete with the establishing corn for resources. In addition, you want to make sure that corn herbicides do not impact the interseeded cover crop. Generally, corn can be interseeded anywhere from the V2 to V6 growth stage. After V6, most interseeding equipment is not tall enough, increasing the risk of damaging the corn crop.

Light available at the time of interseeding varied dramatically across the timing treatments (Figure 19) The arrows indicate the date the corn was interseeded corresponding to the V2, V4, and V6 growth stages. At the V2 and V4 growth stages, virtually none of the PAR was being obstructed by the corn canopy. However, by the time the corn reached the V6 stage, the canopy was already obstructing almost 50% of the light. Light infiltration continued to decline by approximately 10% each week until only 10% of the total light was infiltrating the canopy. This is the level that remained through the remainder of the season.

Despite the significant reduction in light available to the germinating cover crop in later interseedings, all timings supported similar cover crop establishment (Table 35). Post-harvest ground cover averaged 29.2% across the three timings and did not differ statistically. However, the majority of the ground cover was contributed by weeds, not interseeded cover crop species. This suggests that weed pressure throughout the season may have contributed to poor cover crop establishment and performance. As shown in Image 1, the dominant species that established and survived was the tillage radish. This is likely due to its large taproot that allowed it to access the limited moisture in the soil that the clover and annual ryegrass could not. Its wide leaves also allow it to compete for light resources better than the other species. Although the cover crops were assessed approximately 20 days after the corn was harvested, cover crop biomass was still too small to adequately sample. The corn in the trial yielded well averaging 23.7 tons ac-1 and did not vary across interseed timings. It is important to note that no damage was caused to the corn crop either from equipment at later interseedings or competition from the cover crop.

Table 35. Corn and cover crop characteristics by interseed timings, 2020.

Interseed timing

Yield at 35% dry matter

Dry matter

Ground cover

 

tons ac-1

%

% cover crop

% weeds

Total %

V2

22.9

36.8

6.55

28.3

34.8

V4

24.2

36.2

4.76

23.2

28.0

V6

23.9

37.2

5.95

18.8

24.7

LSD (p=0.10)

NS

NS

NS

NS

NS

Trial Mean

23.7

36.7

5.75

23.4

29.2

NS; Not statistically significant at the p=0.10 level.

 

 

Research conclusions:

Interseeding cover crops into corn silage systems is challenging and may be more successful if changes are made to corn variety selection, populations, and the timing of interseeding. During the project period, changes to the corn cropping practices were made and subsequent impacts on cover crop establishment and crop yield were determined. It was determined that light infiltration into the corn canopy was reduced to only 10% just 7 weeks after corn planting. So interseeding the cover crop prior to major reductions in light  penetration should improve establishment. Reducing corn populations also allowed for more light penetration, with corn populations at 28,000 plants per acre resulting in the highest levels of cover crop biomass. Unfortunately, these low corn populations also depressed corn yields compared to seeding rates above 34,000 plants per acre. Hence the best compromise between maximizing corn yields and cover crop biomass was observed when corn populations were 30,000 plants per acre.

Corn variety selection seemed to have variable impacts on cover crop establishment. Corn hybrids are typically characterized as “flex”, “semi-flex”, or “fixed” ear types. Flex ear hybrids are more cost effective when planted at lower seeding rates as they have the ability to adjust corn ear size relative to plant population to remain high yielding despite fewer plants. Fixed ear types, on the other hand, have been bred to remain consistent in ear size regardless of plant population and are therefore become more profitable as populations are increased. These hybrid types also tend to differ in plant architecture or growth habit. Fixed ear hybrids tend to have a more upright leaf structure as they are better suited to the compact nature of high seeding rates. Therefore, we hypothesized that ear type would impact the corn population that would support a high yielding corn crop and successful interseeded cover crop. For the most part, we found that ear type did not significantly impact corn yield or cover crop across corn populations. A larger range of varieties may need to be compared to help farmers determine what locally adapted varieties may be more suitable for interseeding.

Ultimately, the success of interseeding was still most impacted by the amount of soil moisture and weed pressure in the field at the time of seeding. Too much weed pressure at the time of planting was a detriment at both on-farm and research station trials. It was critical to carefully select and apply herbicides to achieve adequate weed control without harming the potential cover crop seedling. In several of the trials weed control was not adequate and led to poor cover crop establishment.

This project helped to further our understanding of how to successfully establish cover crops through interseeding. Modification to corn cropping practices need to be carefully managed to mitigate risk of yield loss the farm. Further data needs to be collected to understand corn variety characteristics that are most suitable for interseeded cover crops.

Participation Summary
8 Farmers participating in research

Education

Educational approach:

This project combined on-farm research and outreach/education methods to transfer information and knowledge to farmers.  In addition to gathering data at farm research locations, we utilized these sites for educational opportunities.  Locations were chosen to be conducive to effective research, but also to be geographically spread out to maximize our outreach efforts. The ability to show producers our results was a major focus of our educational plan.  Seeing results first-hand in the field has a major impact on understanding and the rate of adoption.  In addition to the 10 on-farm field days, we also developed other educational materials including the development of a “Guide to Interseeding Cover Crops” and 2 webinar series addressing practices that lead to successful establishment of interseeded cover crops. We also shared results at the No-Till & Cover Crop Symposium and other regional dairy and forage workshops in VT, ME, NH, NY. Ultimately the project information was able to reach 1,369 individuals at in-person events and another 1,647 individuals during virtual events for a combined audience of 3,016.

In 2018, the project team hosted 3 field days in Vermont. Field days included general information on cover cropping including implementation strategies, benefits, and risks. In addition, information related to soil health was presented to attendees. The 3 fields (Alburgh, Franklin, and Addison) had 210 farmers and 102 other stakeholders in attendance. Flyers from the field days can be found below:

2018-Field-Day-Flyer

Summer Field Day - Franklin

The Cover Crop No-Till Conference held in winter of 2018 allowed the team to introduce the project to a broad group of stakeholders included over 100 farmers and 125 technical service providers (TSPs). In addition, technical cover crop information from both research and practitioners was presented to the audience of 225.

Project outreach also occurred through web resources including an article in a local newsletter (https://www.uvm.edu/sites/default/files/Agriculture/cv-crops-newsletter-2018-fall.pdf) and bulletin (Interseeding Cover Crops into Corn Silage).

In 2019, there were 3 field days in VT and 3 held in ME.

In Vermont, there were 3 meetings held in Alburgh (25-Jul-19;), Franklin (14-Aug-19), and Middlebury (14-May-19) VT. There were a total of 385 participants that attended the events.Topics at the events included cover crop species evaluation trials, cover cropping management, and interseeding equipment, interseeding techniques, corn production for cover crops, and roller-crimping technology. 

In Maine, there were 3 meetings held in Orono (14-Mar-19;), Clinton (21-Aug-19), and Corinna (30-May-19) ME. There were a total of 99 participants that attended the events.Topics at the events included managing herbicides in interseed systems, cover cropping management, and interseeding equipment. 

The Cover Crop No-Till Conference held in winter of 2019 allowed the team to report on the first year of research trials as well as a farmer to farmer session on innovative cover crop techniques. There were 86 farmers and 72 TSPs. In addition, technical cover crop and no-till information from both research and practitioners was presented to the audience of 158.

The Cover Crop No-Till Conference held in winter of 2020 just before the pandemic arrived. Attendance was relatively low due to a snow storm but we were still able to deliver project information to our stakeholders. In addition, technical cover crop information from both research and practitioners was presented to the audience of 120.

In 2020, there were limited in-person outreach events due to the pandemic. However the project team was still able to hold outreach events and provide cover crop information and resources to the farming community

In March and April of 2020, a webinar series as held focused on cover crops and other conservation practices. Attendees participating from throughout the region. Presentations were recorded and archived on YouTube with links below. 

Dig into Your Day with Cover Crops & Conversation webinar series  

Precision Sustainable Agriculture with Steve Mirsky (23 Mar 2020) 123 views https://www.youtube.com/watch?v=kMad0D7WjqQ 

Cover Crops in the Corn/Soybean Rotation with Peter Tomlinson (26 Mar 2020) 99 views https://www.youtube.com/watch?v=K-QHtvmzJaQ 

No-till and Cover Crops in Organic Systems with Joel Gruver (2 Apr 2020) 659 views https://www.youtube.com/watch?v=wQYufKlsm_M 

No-till and Cover Crops in Vegetable Systems with Natalie Lounsbury (6 Apr 2020) 85 views https://www.youtube.com/watch?v=sWDxJhFlGE4 

Stewarding the Birthplace of No-till with John and Alexander Young (Apr 2020) 47 views https://www.youtube.com/watch?v=wMjsg03YJUA 

Cover Crop and Soybean Research with Heather Darby (13 Apr 2020) 76 views https://www.youtube.com/watch?v=oj2GA4g8Ze8 

 
Virtual Friday Field Days were held throughout the growing season highlighting various research projects at Borderview Research Farm. Cover Crops, interseeding, and various experiments associated with these practices were highlighted.
 

Virtual Field Day Fridays 2020

Welcome to our Virtual Field Day Fridays (24 Jul 2020) 76 views https://www.youtube.com/watch?v=wsTHZyOrYLY&feature=youtu.be

Brassica Cover Crops on Vegetable Farms in the Northeast (24 Jul 2020) 59 views https://www.youtube.com/watch?v=RzAe3gFGJpU&feature=youtu.be

Solar Corridors Cropping Systems Experiment (5 Aug 2020) 73 views https://www.youtube.com/watch?v=nM-BO-rNYVk&feature=youtu.be

Interseeding and Equipment at Borderview Research Farm (5 Aug 2020) 86 views https://www.youtube.com/watch?v=EQqtApqE45A&feature=youtu.be

Corn Silage Trials: Flex vs. Fixed, Populations, and Impacts of Drought (19 Aug 2020) 69 views https://www.youtube.com/watch?v=pMDzDqiROGY&feature=youtu.be

A Day at Borderview Research Farm (10 Sep 2020) 47 views https://www.youtube.com/watch?v=vsAAnqYkLCc&feature=youtu.be

Soil Dynamics of Cover Crops: Rye, Vetch, and a Mix (17 Sep 2020) 79 views https://www.youtube.com/watch?v=vX_WWwd1f3I&feature=youtu.be

Winter Terminated Cover Crops UVM (17 Sep 2020) 69 views https://www.youtube.com/watch?v=TFXvYiOsI5Q&feature=youtu.be

 

September 9th, 2020 a field day was held at Misty Meadows farm in ME with 48 participants (state limit of 50 people for outdoor events). Corn varieties as well as interseeding, herbicide issues and 60 inch row corn were discussed.

Finally a Guide to Interseeding was developed and posted to the following link: https://projects.sare.org/information-product/guide-to-interseeding-cover-crops-into-corn-silage-in-the-northeast/

 

Milestones

Milestone #1 (click to expand/collapse)
What beneficiaries do and learn:

1. 1550 dairy farmers in the 5 New England states and northeastern NY will first learn of the project and performance target at the 2018 No-Till/Cover Crop Conference (Burlington, VT; 200 attendees from region). In addition farmers will hear of the project through our outreach networks including social media and newsletters (distribution 1350). March 2018

Proposed number of farmer beneficiaries who will participate:
1550
Actual number of farmer beneficiaries who participated:
1590
Actual number of agriculture service provider beneficiaries who participated:
65
Proposed Completion Date:
March 31, 2018
Status:
Completed
Date Completed:
June 15, 2018
Accomplishments:

The project and performance target was announced at the 2018 No-Till & Cover Crop Symposium held in Burlington, VT on March 1st, 2018. There were 225 attendees from around the region (NY, VT, MA, NH, and Quebec).  Project announcement continued through UVM Extension social media, list serves, and newsletters where we were able to distribute the announcement to 1365 additional stakeholders. A press release was developed and sent to 10 local media outlets for distribution.

Milestone #2 (click to expand/collapse)
What beneficiaries do and learn:

2. Two hundred fifty dairy farmers attend cover crop workshops and webinars and learn about how modifying corn production practices can improve cover crop establishment and benefits. August 2018 & 2019

Proposed number of farmer beneficiaries who will participate:
250
Actual number of farmer beneficiaries who participated:
1500
Actual number of agriculture service provider beneficiaries who participated:
1516
Proposed Completion Date:
August 31, 2019
Status:
Completed
Date Completed:
October 30, 2020
Accomplishments:

This project combined on-farm research and outreach/education methods to transfer information and knowledge to farmers.  In addition to gathering data at farm research locations, we utilized these sites for educational opportunities.  Locations were chosen to be conducive to effective research, but also to be geographically spread out to maximize our outreach efforts. The ability to show producers our results was major focus of our educational plan.  Seeing results first-hand in the field has a major impact on understanding and the rate of adoption.  In addition to the 10 on-farmfield days, we also developed other educational materials including the development of a “Guide to Interseeding Cover Crops” and 2 webinar series addressing practices that lead to successful establishment of interseeded cover crops. We also shared results at the No-Till & Cover Crop Symposium and other regional dairy and forage workshops in VT, ME, NH, NY. Ultimately the project information was able to reach 1,369 individuals at in-person events and another 1,647 individuals during virtual events for a combined audience of 3,016.

 

Milestone #3 (click to expand/collapse)
What beneficiaries do and learn:

3. 4 farmer collaborators will assist with the development and implementation of research to identify best corn practices to establish interseeded cover crops. May 2018; 2019

Proposed number of farmer beneficiaries who will participate:
4
Actual number of farmer beneficiaries who participated:
8
Proposed Completion Date:
May 31, 2019
Status:
Completed
Date Completed:
October 30, 2020
Accomplishments:

1n 2018, on-farm research was established at 3 sites in VT (Machia, Rainville, and Smith) and 3 sites in ME (Barker, Misty Meadow, and Wright). The research trials evaluated the impact of corn variety and corn seeding rate on the establishment of cover crops that have been interseeded. Corn yields were recorded as well as cover crop establishment.

1n 2019, on-farm research was established at 3 sites in VT (Machia, Rainville, and Foster) and 2 sites in ME (Misty Meadow and Leed). The research trials evaluated the impact of corn variety and corn seeding rate on the establishment of cover crops that have been interseeded. Corn yields were recorded as well as cover crop establishment. Unfortunately the ME sites had significant weather challenges and complete data was not collected. Vermont sites were able to repeat the trial at the on-farm locations.

 

Milestone #4 (click to expand/collapse)
What beneficiaries do and learn:

4. 100 farmers attend field days and webinars demonstrating the combination of corn production practices with cover crop interseeding and learn about practical management tools for their operation. August 2020

Proposed number of farmer beneficiaries who will participate:
100
Actual number of farmer beneficiaries who participated:
217
Proposed Completion Date:
August 31, 2020
Status:
Completed
Date Completed:
September 30, 2020
Accomplishments:

Due to the pandemic, a final field day focused on interseeding was not held in 2020 as planned. However,  virtual field days were held focused on interseeding and one on-farm field day held in ME in the fall of 2020. Total attendance at these outreach events was 217.

Milestone #5 (click to expand/collapse)
What beneficiaries do and learn:

5. 50 farmers interested in “trying” interseeding and corn management will receive a project factsheet and enrollment form that outlines expectations. June 2018; 2019

Proposed number of farmer beneficiaries who will participate:
50
Actual number of farmer beneficiaries who participated:
54
Proposed Completion Date:
June 30, 2019
Status:
Completed
Date Completed:
December 31, 2020
Accomplishments:

A flyer was developed to recruit farmers to "try" the practice of interseeding (. The flyer was distributed through emails, newsletters, blogs, and facebook (distribution 1365). Interested farmers contacted the UVM Extension office to participate. Farmers were provided one-on-one technical assistance for interseeding. UVM Extension also completed the interseeding for many farms.

In 2018, interseeding was implemented on 30 farms in partnership with the cost share program funded through the VT Agency of Agriculture Foods and Markets. This totaled 1395 acres of interseeded cover crops.

In 2019, interseeding on-farms continued. There were 9 new farms that worked with UVM to "try" interseeding into 445 acres of corn silage as well as the original 30 farms from 2018.

In 2020, there were an additional 15 new farms to try interseeding on 362 acre through the program again in collaboration with the VT Agency of Agriculture Cover Crop Cost Share Program.

Soil health and yields were collected on the original 30 farms in 2018 and 2020 to verify the performance target. 

Through this collaboration we were able to expand the use of interseeding equipment owned by UVM and expand the practice of interseeding cover cropping and technical assistance we offer on the topic.

Milestone #6 (click to expand/collapse)
What beneficiaries do and learn:

6. The farmers that agree to participate will receive basic recordkeeping notebooks, one-on-one technical assistance with interseeding and implementation of practices and documentation of changes in corn silage cropping system. December 2020

Proposed number of farmer beneficiaries who will participate:
50
Actual number of farmer beneficiaries who participated:
54
Proposed Completion Date:
December 31, 2020
Status:
Completed
Date Completed:
August 31, 2020
Accomplishments:

Farmers were provided one-on-one technical assistance for interseeding. UVM Extension also completed the interseeding for many farms. Farmers were contacted through an online survey to determine success and adoption of practices in the fall of 2020.

Milestone Activities and Participation Summary

Educational activities:

75 Consultations
1 Curricula, factsheets or educational tools
4 On-farm demonstrations
1 Published press articles, newsletters
10 Webinars / talks / presentations
9 Workshop field days

Participation Summary:

552 Farmers
466 Number of agricultural educator or service providers reached through education and outreach activities

Learning Outcomes

122 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
56 Agricultural service providers reported changes in knowledge, skills, and/or attitudes as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

Farmers were provided a post event survey at the no-till & cover crop conference. Farmers involved with verification of performance target were also surveyed at start of the project and at completion.

The most common changes in attitude and skills as noted through surveys and conversations included:

Farmers planning to increase cover crop acreage

Farmers changing herbicide program to enhance cover crop.

Farmers increasing cover crop species diversity.

Farmers changing corn variety to enhance cover crop. 

Farmers also expressed increased knowledge in corn production factors that could be modified to enhance cover crop but not sacrifice yield. 

Performance Target Outcomes

Target #1

Target: number of farmers:
25
Target: change/adoption:

Farmers will adopt a new corn production practice such as corn variety, corn population, or herbicide program to encourage the establishment of interseeded cover crops.

Target: amount of production affected:

fine hundred acres of corn silage was affected by the adoption of new corn production practices.

Target: quantified benefit(s):

On average, farmers will observe a 2 ton per acre yield increase.

Actual: number of farmers:
30
Actual: change/adoption:

Thirty farms modified a crop production practice that included one or more of the following practices: variety, corn populations, and/or herbicide to enhance cover crop establishment.

Actual: amount of production affected:

There were 1500 acres affected by the change.

Actual: quantified benefit(s):

Soil health scores of cover cropped fields averaged 79.6 (high functioning) and 1.2 ton increase in corn silage yields.

Performance Target Outcome Narrative:

Impact of Modifying Corn Practices on Cover Crop Interseeding Biomass, Soil Health, and Corn Yields

In collaboration with the Vermont Cover Crop Cost Share Program, 30 farms from northern, VT were enrolled in our SARE research/education grant. Working with the Vermont Agency of Agriculture and collaborating farmers we were able to collect yields and soil health samples prior to cover cropping.  The project team interacted with the collaborating farms to select corn practices, herbicides, cover crop species. Interseeding equipment was also made available to collaborating farms. Yield and soil health was monitored on 1395 acres. 

The Cover Crop Cost Share Program paid for the cover cropping and other cost share dollars paid for soil sampling. It was an excellent collaboration that allowed our team to not only expand the adoption of strategies to enhance interseeding but also to track soil and yield data across a large number of farms. This information was used to help verify the performance target. Soil samples were sent to the Cornell Soil Health Laboratory to collect a baseline and a final soil health assessment in the fall of 2020. 

In 2018, the interseeded fields had the lowest soil health score was 56.2%, the highest was 82.7% with an average across all fields of 66.9%. In 2020, the average soil health score across all fields was 79.6% with the higher score of 94.2%. These soil health test scores fall in the very high functioning range indicating excellent soil health. When evaluating individual soil health indicators, cover crops consistently improved soil respiration on all fields over the baseline. In addition, surface compaction was alleviated with the use of tillage radishes in the field. 

Yields were collected and reported by farmers in 2018 (prior to cover cropping) and 2020 post cover cropping. The yield increased in cover crop fields by 1.2 tons per acre. There was much variability between fields. The highest increase observed was 5.2 tons per acre and in 5 of the 30 fields there was no yield increase on the cover crop fields. 

However, across all 1395 acres there was a reported yield and soil health increase as a result of  cover cropping. A target of 2 ton per acre yield was proposed in the original performance target. This yield increase was based on past research with VT farmers. We may not have observed this level of yield increase due to the short term nature of the project.  

In addition to this on-farm verification, an additional 24 farms were able to utilize the UVM interseeding equipment, receive one-on-one technical assistance and provide program feedback. A flyer was developed to recruit farmers to "try" the practice of interseeding (. The flyer was distributed through emails, newsletters, blogs, and facebook (distribution 1365). Interested farmers contacted the UVM Extension office to participate. Farmers were provided one-on-one technical assistance for interseeding. UVM Extension also completed the interseeding for many farms.

In 2018, interseeding was implemented on 30 farms in partnership with the cost share program funded through the VT Agency of Agriculture Foods and Markets. This totaled 1395 acres of interseeded cover crops.

In 2019, interseeding on-farms continued. There were 9 new farms that worked with UVM to "try" interseeding into 445 acres of corn silage as well as the original 30 farms from 2018.

In 2020, there were an additional 15 new farms to try interseeding on 362 acre through the program again in collaboration with the VT Agency of Agriculture Cover Crop Cost Share Program.

A total of 2,202 acres were interseeded on 56 farms in this project 

54 Farmers changed or adopted a practice

Additional Project Outcomes

3 Grants applied for that built upon this project
2 Grants received that built upon this project
$100,000.00 Dollar amount of grants received that built upon this project
2 New working collaborations
Additional Outcomes:

Like much research, this project generated more questions and provided new opportunities to collaborate with farmers and organizations around shared goals. Since cover crop establishment remained variable at many sites, we brainstormed with farmers on ideas to strengthen this practice. Collaborating farmers had read about growers in IA that were deploying a Solar Corridor Cropping System. This system plants corn with 60 inches between the crop rows. In the 60 inch space, farmers are planting cover crops. This larger space allows better cover crop establishment but might lead to corn yield losses. This system is being experimented with with grain corn and in beef systems. Several grant proposals were submitted to raise funds for this research. A SARE R&E grant was applied for in 2020 and not awarded. However, the farmers and Darby teamed up again a submitted a partnership grant in 2021. The grant was recently awarded and will allows farmers to test the Soil Corridor System in corn silage and dairy systems. In addition, to the SARE partnership grant Ben & Jerry's Homemade Inc. has also provided some funds to keep evaluating interseeding in corn silage systems. Lastly, a national CIG grant was awarded to extend interseeding equipment to more farms in VT. 

Assessment of Project Approach and Areas of Further Study:

Unfortunately, interseeding still remained largely variable even with our research on modifying corn practices to enhance success. When evaluating the data from all the trials, there were 2 factors that contributed the most to cover crop interseeding success, moisture after planting and herbicide residues. Additional research to evaluate herbicide programs suitable for interseeding is necessary. Research that provides further details on corn variety selection for cover crop interseed establishment would also be critical. 

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.