Final report for ONE21-386
Project Information
Solar Corridor Systems integrates row crops with solid-seeded crops in broad strips. The broad strips (corridors) allow for more efficient capture of solar radiation by each crop. Solar corridors are a variation on intercropping and allows for the production of two or more cash crops or a cash crop with a cover crop. This strategy may allow farmers to select cover crops that maximize nutrient cycling or increase forage production and help reduce farm costs, off-farm inputs, and improve cover crop adoption. The goal of this project was to develop Solar Corridor Systems that are feasible for corn silage production systems in Vermont. The first objective was to evaluate the effect of corn row widths and corn population on silage yield/quality as well as cover crop biomass. Row widths evaluated were 20, 30, 36, 40, and 60 inches between rows of corn. Corn silage yields were lowest for the corn grown in 60 inch rows. Depending on the year, comparable corn silage yields were obtained with 20, 30, 36, and 40 inches between rows. Ideal corn population for growing corn silage is 32,000 plants per acre. Obtaining that population helps to optimize both yield and quality. Maintaining or achieving ideal corn populations in wider rows may be difficult to impossible depending on the type of planting equipment. A row-width by corn population study was conducted to understand ideal corn populations for maximizing yield and quality of wide row corn. However, the study did not result in any significant yield differences regardless of population in 30 or 60 inch row spacing. There was a trend that indicated growing 60 inch row corn at standard silage rates would lead to lower quality likely due to smaller ears and more competition in the row for nutrients and resources. Hence further studies should investigate optimum seeding rates for corn grown in 60 inch rows that optimizes yield and quality. The second objective was to evaluate the effect of corn row width on establishment and productivity of forage based cover crops corn. Establishing a forage earlier in the corn rotation could improve farm economics. Generally the forage crop takes nearly a year to establish and yields in the first year are really limited. Establishing the forage in the corn year would lead to a full year of forage production the following season instead of just a partial yield. Interseeding forages into the growing corn did prove successful however, wider row corn had better establishment come the fall months. Both alfalfa, orchardgrass, and mixtures established adequately in the 60 inch corn with only alfalfa establishing in the 30 inch rows. More research needs to be conducted to track forage productivity the following year. Overall the concept of Solar Corridor Systems holds promise in the northeast corn silage system however more research is needed to overcome yield decline in the wide row corn. Information on Solar Corridor Systems as well as general information on cover crops were shared with 184 farmers and 243 other stakeholders through field days, on-farm demonstrations, virtual events, and guides.
This project seeks to develop Solar Corridor Systems that are feasible for corn silage production systems in Vermont. The successful Solar Corridor System will optimize cover crop benefits and maintain corn silage yield and quality. To develop a successful Solar Corridor System we will develop research with the following objectives:
Objective 1: Evaluate the effect of corn row widths and corn population on silage yield/quality as well as cover crop biomass.
Objective 2: Evaluate the effect of corn row width on establishment and productivity of forage based cover crops corn.
Farmers will benefit from the results by learning more about how to adapt corn silage production systems to reap the numerous benefits of cover cropping. Dairy farmers in Vermont are currently harvesting cover crops as forage adding additional benefits to the practice. A successful Solar Corridor System may further help farmers reap the benefits of cover cropping and crop diversity.
Although substantial gains in cover crop acreage have been seen across the northeast, proper establishment of cover crops continues to be challenging for dairy operations which rely heavily on corn silage. To overcome barriers associated with a short growing season, farmers have focused on interseeding techniques to establish cover crops into cash crops, however, limited success has been observed primarily due to significant reductions in light infiltration through the corn canopy. One factor is the pressure to maximize yields which encourages planting corn silage at populations ranging from 32,000-40,000 plants per acre. This reduces the amount of sunlight available to an interseeded crop.
Farmers have demonstrated their desire to cover crop and ability to integrate new practices into their operations. However, 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. In a recent SARE grant (LNE18-361), Darby and 30 farm partners evaluated corn variety selection, corn population, and interseed timing to increase light infiltration and improve cover crop establishment. Results still remain highly variable.
In 2019, Darby and local farmers began to research the impact of corn row spacing on establishment of interseeded cover crops. Cover crops interseed into corn planted in wide rows (60 versus 30 inches) had 100% increase in cover crop biomass but corn yields were suppressed 3 tons/acre. This strategy is referred to as a Solar Corridor System that integrates row crops with solid-seeded crops in broad strips. The broad strips (corridors) allow for more efficient capture of solar radiation by each crop. Solar corridors are a variation on intercropping and allows for the production of two or more cash crops or a cash crop with a cover crop (Deichman, 2009). This strategy may allow farmers to select cover crops that maximize nutrient cycling or increase forage production and help reduce farm costs, off-farm inputs, and improve cover crop adoption.
Overall, VT farmers were very positive and felt the practice deserved more attention and that tweaks to the row spacing and population might close the yield gap. In addition, it was unclear if the cover crop in the solar corridor could be further utilized for forage. It is plausible that a cover crop species may make up for lost corn yield by providing additional forage, nutrients, and other benefits that may reduce on-farm inputs. As an example, Wisconsin research showed that successful interseeding of alfalfa into corn improved overall forage yields in a corn/alfalfa rotation (Osterholz et al., 2020).
Research is needed to understand the advantages and disadvantages of various row arrangements for corn silage systems, which cover crops are most successful in these systems, and which cover crops can provide the most benefit (i.e additional forage). Solar corridors are a relatively new cover cropping strategy and the information provided through this research will be used to create effective strategies for implementation in corn silage production systems.
Cooperators
- - Producer
- - Producer
- (Researcher)
- - Producer
- - Producer
Research
We propose that changes in corn silage production practices combined with cover crop species selection can improve the establishment and value of interseeded cover crops. In 2022 and 2023, these trials were initiated to evaluate a Solar Corridor System. This system is a modification to intercropping and allows a farmer to increase diversity in their field. The main feature of the Solar Corridor System is use of wide row widths that allows full exposure of tall crops such as corn to sunlight while integrating lower growing crops between the rows of corn.
MATERIALS AND METHODS
All field trials were conducted at Borderview Research Farm, Alburgh, VT.
Trial 1 evaluated the effect of corn row width on silage yield and quality.
Trial 2 evaluated the impact of corn row width on silage yield, as well as biomass production of three interseeded forage crop treatments.
Trial 3 evaluated the impact of corn row width and corn population on silage yield and quality.
The on-farm research trials were conducted in St. Albans, Enosburg, and Fairfax, VT and evaluated the impact of row width on corn yields and interseeded forage crop establishment.
Trial 1 – The impact of corn row width on silage productivity
The experimental design for Trial 1 was a randomized complete block design where the treatments were corn row widths (20”, 30”, 36”, 40” and 60” row spacings) and were replicated six times. Plots were 40’ long and consisted of 4 rows. To accommodate wider row spacing, plot size was adjusted based on the corn row width. Plots were 8’, 10’, 12’, 14’ and 20’ wide for 20”, 30”, 36”, 40” and 60” spacing respectively.
In 2022 the corn was planted on 25-May and in 2023 on the 16-May. The 30” and 60” plots were planted with a John Deere MaxEmerge 1750 4-row planter (Moline, IL). The 20”, 36” and 40” plots were planted with a custom-made planter that included John Deere plate row-units on an adjustable tool bar. All plots were planted to meet a target population of 30,000 plants ac-1. All plots were interseeded with a cover crop mixture of annual ryegrass (60%), red clover (30%) and tillage radish (10%) on 6-Jul in 2022 and 22 Jun in 2023.
Light intensity was measured using HOBO® pendant temperature and light sensors from Onset Computer Corporation (Bourne, MA). Sensors were set to log the light information every two hours and report light intensity in lumens ft-2. Sensors were placed just above the soil surface between rows of corn and a control was placed outside of the corn rows. Corn plant population at harvest was assessed by counting the number of plants in the center two rows of each plot. Corn was harvested on 30-Sep on 2022 and 27-Sep in 2023 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 1 lb. subsample was collected, weighed, dried, and weighed again to determine dry matter content and calculate yield. Cover crop biomass was not measured in this trial.
The dried forage subsamples were ground to 2mm using a Wiley sample mill and then to 1mm using a cyclone sample mill (UDY Corporation). The samples were analyzed at the E. E. Cummings Crop Testing Laboratory at the University of Vermont (Burlington, VT) with a FOSS NIRS (near infrared reflectance spectroscopy) DS2500 Feed and Forage analyzer. The NIR procedures and corn silage calibration from Dairy One Forage Laboratories (Geneva, NY) were used to determine crude protein (CP), starch, lignin, ash, ash corrected neutral detergent fiber (aNDFom), total digestible nutrients (TDN), net energy lactation (NEL), undigestible neutral detergent fiber (uNDFom; 30h), and neutral detergent fiber digestibility (NDFD; 30h).
Trial 2 – The impact of corn row width on silage productivity and establishment of interseeded forages
The experimental design for Trial 2 was a randomized complete block with split plot design and replicated four times. Main plots were corn row widths (30”, 40” and 60”) and split plots were interseeded forage treatments (alfalfa, orchardgrass/ alfalfa mix, and orchardgrass). The forage treatment descriptions can be found in Table 1. All plots were 35’ long and consisted of 4 rows. To accommodate the wider row spacing, plots were 10’, 14’ and 20’ wide for 30”, 40” and 60” row spacing respectively. Seeding rate was adjusted based on row width. The 30” and 60” plots were planted with a John Deere MaxEmerge 1750 4-row planter (Moline, IL). The 20”, 36” and 40” plots were planted with a custom-made planter that included John Deere plate row-units on an adjustable tool bar. All plots were planted to meet a target population of 30,000 plants ac-1. Forages were interseeded on 6 Jul in 2022 and 20-Jun in 2023, at a rate of 20 lbs. ac-1. On 30-Sep, prior to corn harvest, ground cover by interseeded forage was measured by processing photographs using the Canopeo© smartphone application. Forage establishment was poor; therefore, biomass samples were not collected prior to harvest. Corn plant populations at harvest were assessed by counting the number of plants in the center two rows of each plot. On 30-Sep in 2022 and 27-Sep in 2023, corn from Trial 2 was harvested as described in Trial 1. An approximate 1 lb. representative subsample was collected for each row width, weighed, dried, and weighed again to determine dry matter content. Quality analyses were not conducted on corn silage from Trial 2.
Table 1. Replicated trial forage treatment seeding rates, Alburgh, VT, 2023.
|
Forage treatment |
Seeding rate (lbs. ac-1) |
|
VNS alfalfa |
20 |
|
Harvestar orchardgrass/ VNS alfalfa |
8 |
|
12 |
|
|
Harvestar orchardgrass |
20 |
On-farm research trials to evaluate the effect of row width on corn yields and establishment of interseeded forages
In 2022, two on-farm trials were conducted in St. Albans and Enosburg, Vermont. In the on-farm trial in St. Albans, corn was planted on 7-May using a John Deere 7200 planter. Row units were individually controlled by Ag Leader® SureDrive electric drives. Row widths were 30” and 60”. The 30” rows were planted at a rate of 30,000 seeds ac-1 and the 60” rows at a rate of 60,000 seeds ac-1 to reach the target corn population of 30,000 plants ac-1. Starter fertilizer (32-0-0) was applied at a rate of 8 gal ac-1. Alfalfa was interseeded on 22-Jun at a rate of 20 lbs ac-1. On 7-Sep, corn populations were measured in both 30” and 60” rows by counting the number of plants in two 10ft sections. Corn yield was also measured by collecting and weighing the plants from the two 10ft sections in each plot. After weighing, five corn plants were ground through a woodchipper and an approximate 1lb subsample was collected, weighed, dried, and reweighed to determine dry matter content and yield. Subsamples were ground and analyzed for forage quality following the same procedures outlined for Trial 1. Interseeded forage establishment and growth was minimal in the 30” rows and was not measured. In the 60” rows, forage height and biomass were recorded at the time of corn harvest. Alfalfa was collected from three 9 in2 quadrats then weighed, dried, and reweighed to determine yield. In the on-farm trial in Enosburgh, VT, corn was planted on 8-May using a Great Plains 1225 planter. Row widths were 20” and 40”. The 20” rows were planted at a rate of 34,000 seeds ac-1 and the 40” rows at a rate of 68,000 seeds ac-1 to meet the target corn population of 34,000 plants ac-1. Starter fertilizer, 9-18-9 and 32-0-0, was applied at a rate of 5 gal and 10-gal ac-1 respectively. Alfalfa was interseeded on 2-Jul at a rate of 20 lbs ac-1. Corn was harvested by the farmer on 1-Oct and yields were recorded using a yield monitor and were reported at harvest moisture. Interseeded forage establishment and growth was not recorded in the 20” rows due to poor establishment and growth. In the 40” rows, after the corn was harvested, alfalfa height was recorded, and a representative composite sample of alfalfa was collected by clipping plant material within three 9 in2 quadrats. The sample was weighed, dried, and reweighed to calculate yield. Quality analyses were not conducted on corn or alfalfa from the on-farm trial in Enosburg, VT. Statistical analyses were not done on data collected in either on-farm trial.
In 2023, three on-farm research trials were conducted in St. Albans, VT, Highgate, VT, and Fairfax, VT. These trials evaluated the impact of two row widths, 30” and 60”, on corn yields and interseeded forage crop establishment.
In St. Albans, corn was planted on 12-May using a John Deere 7200 planter. Row units were individually controlled by Ag Leader® SureDrive electric drives. Row widths were 30” and 60”. The 30” rows were planted at a rate of 30,000 seeds ac-1 and the 60” rows at a rate of 60,000 seeds ac-1 to reach the target corn population of 30,000 plants ac-1 overall. Starter fertilizer (32-0-0) was applied at a rate of 8 gal ac-1. Alfalfa was interseeded on 21-Jun at a rate of 20 lbs ac-1. On 25-Sep, corn populations were measured in both 30” and 60” rows by counting the number of plants in 10ft sections. Corn yield was also measured by collecting and weighing the plants from the 10ft sections in each treatment area. After weighing, five corn plants were ground through a woodchipper and an approximate 1lb subsample was collected, weighed, dried, and reweighed to determine dry matter content and yield. Subsamples were ground and analyzed for forage quality at the University of Vermont Cereal Grain Testing Laboratory (Burlington, VT) via near infrared reflectance spectroscopy (NIR) techniques using a FOSS DS2500 Feed and Forage Analyzer. Forage establishment was measured by collecting the material growing within three quadrats that were approximately 0.05m2 each then weighed, dried, and reweighed to determine dry matter yield.
In the on-farm trial in Highgate, VT, corn was planted on 17-May using a John Deere 7200 planter. Row units were individually controlled by Ag Leader® SureDrive electric drives. Row widths were 30” and 60”. The 30” rows were planted at a rate of 30,000 seeds ac-1 and the 60” rows at a rate of 60,000 seeds ac-1 to meet the target corn population of 30,000 plants ac-1. Starter fertilizer, 32-0-0, was applied at a rate of 8-gal ac-1. The orchardgrass/alfalfa mixture was interseeded on 21-Jun at a rate of 20 lbs ac-1. Prior to harvest on 2-Oct, corn populations, yield, and forage establishment were measured as described for the previous on-farm trial.
In the on-farm trial in Fairfax, VT, corn was planted on 31-May using a using a John Deere 7200 planter . Row units were individually controlled by Ag Leader® SureDrive electric drives. Row widths were 30” and 60”. The 30” rows were planted at a rate of 30,000 seeds ac-1 and the 60” rows at a rate of 60,000 seeds ac-1 to meet the target corn population of 30,000 plants ac-1. Starter fertilizer, 32-0-0, was applied at a rate of 8-gal ac-1. The orchardgrass/alfalfa mixture was interseeded on 3-Jul at a rate of 20 lbs ac-1. Prior to harvest on 2-Oct, corn populations, yield, and forage establishment were measured as described for the previous on-farm trial.
Trial 3- The impact of corn row width and population on silage productivity
The experimental design for Trial 3 was a randomized complete block with three replicates. Corn was planted in 30” and 60” rows at populations ranging from 22,000 to 32,000 seeds ac-1. Each plot was assigned a row width and a target population. Treatment descriptions are in Table 2 below. Plots were 20’ long and consisted of 4 rows. To accommodate wider row spacing, plot size was adjusted based on the corn row width. Plots were 10’ wide for 30” row spacing and 20’ wide for 60” row spacing. Corn was planted on 12-May in2023 using a 4-row cone planter with John Deere row units fitted with Almaco seed distribution units (Nevada, IA). All plots were interseeded with a cover crop mixture of annual ryegrass (60%), red clover (30%) and tillage radish (10%). Corn plant population at harvest was assessed by counting the number of plants in the center two rows of each plot. Cover crop biomass was not measured in this trial. On 21-Sep, corn from Trial 2 was harvested as noted in Trial 1. An approximate 1 lb. representative subsample was collected for each row width, weighed, dried, and weighed again to determine dry matter content. The dried forage subsamples were ground and analyzed as described in Trial 1.
Table 2. Corn row spacing by population treatment descriptions.
|
Treatment |
Row width |
Target population |
|
inches |
plants ac-1 |
|
|
30 - 22,000 |
30 |
22,000 |
|
30 - 25,000 |
25,000 |
|
|
30 - 28,000 |
28,000 |
|
|
30 - 30,000 |
30,000 |
|
|
30 - 32,000 |
32,000 |
|
|
60 - 22,000 |
60 |
22,000 |
|
60 - 25,000 |
25,000 |
|
|
60 - 28,000 |
28,000 |
|
|
60 - 30,000 |
30,000 |
|
|
60 - 32,000 |
32,000 |
Data were analyzed using a general linear model procedure of SAS (SAS Institute, 1999). Replications were treated as random effects, and treatments were treated as fixed. Mean comparisons were made using the Least Significant Difference (LSD) procedure where the F-test was considered significant, at p<0.10.
In 2022, weather data were recorded with a Davis Instrument Vantage Pro2 weather station, equipped with a WeatherLink data logger at Borderview Research Farm in Alburgh (Table 3), in St. Albans (Table 4), and in Enosburg, VT (Table 5). In Alburgh, temperatures were below normal throughout the growing season. May was the only month that had warmer than average temperatures. From May through September, Alburgh received 23.89 inches of rain, which is almost twice as much precipitation received in 2021. The accumulated rainfall in Alburgh was 4.6 inches higher than the 30-year normal for May through September. This season, in Alburgh, there were 2500 Growing Degree Days (GDDs) which falls within the range of required GDDs for corn silage (2,200 to 2,800). Unlike Alburgh, the temperatures at the St. Albans location were warmer than normal from May through September. May and August were 4.53 and 4.22 degrees above the 30-year average respectively. Like Alburgh, precipitation was higher than normal, and there was a total of 21.8 inches of rain, 2.66 inches above normal. Overall, there were 2597 accumulated GDDs. At the Enosburg location, precipitation was higher than normal as well, with above average rainfall in May, June, and September. There was a total of 26.3 inches of rain, 5.68 above normal. Overall, there were 2275 accumulated GDDs at the Enosburg location. Both of the on-farm locations had a sufficient number of GDDs for corn silage.
Table 3. Weather data for Trial 1 and 2, Alburgh, VT, 2022.
|
Alburgh, VT |
May |
June |
July |
August |
Sept |
|
Average temperature (°F) |
60.5 |
65.3 |
71.9 |
70.5 |
60.7 |
|
Departure from normal |
2.09 |
-2.18 |
-0.54 |
-0.20 |
-1.99 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
3.36 |
8.19 |
3 |
4.94 |
4.4 |
|
Departure from normal |
-0.40 |
3.93 |
-1.06 |
1.40 |
0.73 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
394 |
459 |
674 |
630 |
343 |
|
Departure from normal |
93 |
-64 |
-20 |
-11 |
-44 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from Burlington, VT.
Table 4. Weather data for the on-farm trial in St. Albans, VT, 2022.
|
|
2022 |
||||
|
St. Albans, VT |
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
60.5 |
65.9 |
72.9 |
72.2 |
61.5 |
|
Departure from normal |
4.53 |
0.81 |
2.83 |
4.22 |
1.34 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
3.22 |
4.96 |
5.1 |
4.79 |
3.71 |
|
Departure from normal |
-0.02 |
0.85 |
1.00 |
1.05 |
-0.22 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
407 |
481 |
681 |
655 |
373 |
|
Departure from normal |
162 |
28 |
56 |
96 |
54 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from St. Albans, VT.
Table 5. Weather data for the on-farm trial in Enosburg, VT, 2022.
|
|
2022 |
||||
|
Enosburg, VT |
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
59.7 |
63.4 |
69.6 |
69.1 |
58.6 |
|
Departure from normal |
3.10 |
-1.60 |
0.10 |
1.20 |
-1.90 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
5.38 |
6.16 |
4.18 |
3.28 |
7.33 |
|
Departure from normal |
1.71 |
1.78 |
-0.07 |
-1.10 |
3.36 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
367 |
411 |
609 |
590 |
299 |
|
Departure from normal |
60 |
-39 |
3 |
35 |
-48 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from Enosburg Falls, VT.
Weather data were recorded with a Davis Instrument Vantage Pro2 weather station, equipped with a WeatherLink data logger at Borderview Research Farm in Alburgh (Table 6), in St. Albans (Table 7), Highgate (Table 8), and Fairfax, VT (Table 9). In Alburgh, temperatures were below normal throughout the growing season. September was the only month that had warmer than average temperatures. From May through September, Alburgh received 25.8 inches of rain, 6.5 inches higher than the 30-year normal for May through September. This season, in Alburgh, there were 2487 Growing Degree Days (GDDs) which falls within the range of required GDDs for corn silage (2200 to 2800) but 62 fewer than normal. Similar conditions were observed at the on-farm sites with below normal temperatures through the season, especially in August. Precipitation totals were 22.0, 25.8, and 26.4 inches for the St. Albans, Highgate, and Fairfax locations respectively and were 2.7, 6.5, and 7.0 inches above normal. GDDs were lowest at the Fairfax site totaling 2321 and highest in St. Albans at 2544 with Highgate in between at 2431.
Table 6. Weather data for replicated trial, Alburgh, VT, 2023.
|
Alburgh, VT |
May |
June |
July |
August |
Sept |
|
Average temperature (°F) |
57.1 |
65.7 |
72.2 |
67.0 |
63.7 |
|
Departure from normal |
-1.28 |
-1.76 |
-0.24 |
-3.73 |
1.03 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
1.98 |
4.40 |
10.8 |
6.27 |
2.40 |
|
Departure from normal |
-1.78 |
0.14 |
6.69 |
2.73 |
-1.27 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
303 |
483 |
712 |
540 |
449 |
|
Departure from normal |
1 |
-41 |
17 |
-101 |
62 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from Burlington, VT.
Table 7. Weather data for the on-farm trial in St. Albans, VT, 2023.
|
St. Albans, VT |
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
59.7 |
66.3 |
73.4 |
68.1 |
64.8 |
|
Departure from normal |
1.35 |
-1.15 |
0.96 |
-2.65 |
0.08 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
1.53 |
3.60 |
9.19 |
4.97 |
2.72 |
|
Departure from normal |
-2.23 |
-0.66 |
5.13 |
1.43 |
-0.95 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
324 |
489 |
726 |
561 |
444 |
|
Departure from normal |
22 |
-35 |
31 |
-80 |
57 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from Burlington, VT.
Table 8. Weather data for the on-farm trial in Highgate, VT, 2023.
|
Highgate, VT |
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
59.7 |
65.8 |
72.0 |
67.1 |
64.2 |
|
Departure from normal |
1.27 |
-1.62 |
-0.43 |
-3.68 |
-0.53 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
2.02 |
3.96 |
10.7 |
6.32 |
2.80 |
|
Departure from normal |
-1.74 |
-0.30 |
6.65 |
2.78 |
-0.87 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
319 |
475 |
682 |
529 |
426 |
|
Departure from normal |
17 |
-49 |
-13 |
-112 |
39 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from Burlington, VT.
Table 9. Weather data for the on-farm trial in Fairfax, VT, 2023.
|
Fairfax, VT |
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
59.0 |
64.8 |
71.5 |
66.0 |
63.8 |
|
Departure from normal |
0.65 |
-2.64 |
-0.90 |
-4.71 |
-0.97 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
1.81 |
5.70 |
8.80 |
6.91 |
3.14 |
|
Departure from normal |
-1.95 |
1.44 |
4.74 |
3.37 |
-0.53 |
|
|
|
|
|
|
|
|
Growing Degree Days (50-86°F) |
298 |
445 |
668 |
497 |
413 |
|
Departure from normal |
-4 |
-79 |
-27 |
-144 |
26 |
Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger.
Historical averages are for 30 years of NOAA data (1991-2020) from Burlington, VT.
Trial 1- The impact of corn row width on silage productivity
In 2022, harvest population and yield at 35% dry matter were significantly impacted by the row spacing treatments (Table 10). Corn populations were significantly greater in the 30” rows at harvest compared to the other row widths, with 31,363 plants ac-1. All the other treatments had populations below the seeding rate target of 30,000 plants ac-1. Harvest dry matter was not significantly different between the treatments, and all had a dry matter close to the target of 35% and ranged from 35.7-37.6%. Corn yield was highest in the 30” rows (25.5 tons ac-1) but was not statistically different from the 20” rows (24.9 tons ac-1). The 40” and 60” rows had the lowest yields, 18.1- and 18.5-tons ac-1 respectively. The higher yields in the 20” and 30” rows are likely because of the higher plant populations at harvest. There were no significant differences in silage quality between the row widths (Table 11).
Table 10. Corn silage yield by row width in Trial 1, Alburgh, VT, 2022.
|
Row width |
Harvest population |
Dry matter |
Yield, 35% DM |
|
plants ac-1 |
% |
tons ac-1 |
|
|
20-in. |
29144b† |
36.9 |
24.9ab |
|
30-in. |
31363a |
37.6 |
25.5a |
|
36-in. |
28465b |
36.4 |
22.3b |
|
40-in. |
26343c |
37.0 |
18.1c |
|
60-in. |
25573c |
35.7 |
18.5c |
|
LSD (p=0.10) ‡ |
1674.2 |
NS§ |
2.65 |
|
Trial mean |
28178 |
36.7 |
21.9 |
†Treatments within a column with the same letter are statistically similar. Top performers are in bold.
‡LSD –Least significant difference at p=0.10.
§NS- No significant difference at p=0.10.
Table 11. Corn silage quality by row width in Trial 1, Alburgh, VT, 2022.
|
Row width
|
Starch |
Crude protein |
aNDFom |
TDN |
30-hr uNDFom |
30-hr NDFD |
NEL |
Milk |
|
|
--------------% of DM---------------- |
% of NDF |
Mcal lb-1 |
lbs. ton-1 |
lbs. ac-1 |
|||||
|
20-in. |
32.5 |
8.50 |
40.3 |
63.5 |
16.6 |
59.0 |
0.658 |
2245 |
19086 |
|
30-in. |
29.9 |
8.70 |
42.9 |
62.8 |
17.7 |
58.8 |
0.639 |
2118 |
18775 |
|
36-in. |
31.8 |
8.90 |
41.5 |
63.0 |
17.6 |
57.7 |
0.648 |
2297 |
17722 |
|
40-in. |
32.7 |
9.20 |
40.3 |
63.5 |
16.3 |
59.6 |
0.657 |
2306 |
14703 |
|
60-in. |
33.5 |
8.70 |
38.9 |
64.0 |
15.9 |
59.2 |
0.667 |
2376 |
15872 |
|
LSD (p = 0.10) ‡ |
NS§ |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
|
Trial mean |
32.1 |
8.80 |
40.8 |
63.4 |
16.8 |
58.8 |
0.654 |
2268 |
17231 |
‡LSD –Least significant difference at p=0.10.
§NS- No significant difference at p=0.10.
Light sensors were placed in between the rows of corn to measure the intensity of light reaching the soil surface and a control was placed outside of the corn rows. The light intensity, measured in accumulated lumens ft-2, was similar for all row widths and the control during the first two weeks after the cover crop was interseeded (Figure 1). This figure provides a visualization of light intensity but does not, however, state that these differences are statistically significant. The 20” and 30” rows had the least amount of light reaching the soil surface, and there was little difference between the two treatments. Light intensity was greater throughout the season in the 40” rows compared to the 60” rows. Increased weed pressure in the wider row widths continues to be a challenge and may have resulted in this trend. Light sensors were removed approximately 3 weeks before harvest, and at that time, the rate of change of accumulated lumens ft-2 had slowed down, and there would likely be little increase in accumulated lumens ft2 in any of the treatments except for the control due to canopy closure.
In 2023, corn harvest characteristics for Trial 1 are summarized in Table 12 below. The average dry matter at harvest was 37.6%, and there were no significant differences between treatments. Corn silage yield was significantly greater in the 20” plots with an average yield of 30.1 tons ac-1. This was not statistically different from the 40” plots, which had an average yield of 26.5 tons ac-1. Silage yields were lowest in the 60” plots but were not statistically different from the 36” plots.
Table 12. Corn harvest characteristics for Trial 1, Alburgh, VT, 2023.
|
Row width |
Dry matter |
Yield, 35% DM |
|
|
inches |
% |
tons ac-1 |
|
|
20 |
39.1 |
30.1a† |
|
|
30 |
35.5 |
25.4b |
|
|
36 |
37.3 |
25.0bc |
|
|
40 |
37.7 |
26.5ab |
|
|
60 |
38.1 |
20.7c |
|
|
LSD (p=0.10)‡ |
NS§ |
4.47 |
|
|
Trial mean |
37.6 |
25.6 |
†Within a column, treatments marked with the same letter are statistically similar (p=0.10); top performer is in bold.
‡LSD; least significant difference at the p=0.10.
§NS; no significant difference between treatments.
There were very few significant differences in quality between treatments (Table 13). The average crude protein was 7.61%. Silage in the 36” plots had the greatest crude protein, 7.90%, but this was not statistically different from the 20”, 30”, or 40” plots. Silage in the 60” plots had significantly lower crude protein than the other four row widths. The average estimated milk per ton of feed was 3,284 lbs, and there were no statistical differences between the treatments. The 20” plots had the highest estimated milk per acre, 34,575 lbs. This was not statistically different from the 30” and 40” plots.
Table 13. Corn quality characteristics for Trial 1, Alburgh, VT, 2023.
|
Treatment |
CP |
ADF |
aNDFom |
Lignin |
NFC |
Starch |
TDN |
30-hr uNDFom |
30-hr NDFD |
NEL |
Milk |
|
|
|
--------------% of DM---------------- |
% of NDF |
Mcal lb-1 |
lbs. ton-1 |
lbs. ac-1 |
|||||||
|
20 |
7.58a† |
22.4 |
38.3 |
2.83 |
46.1 |
36.5 |
64.0 |
17.4 |
54.6 |
0.667 |
3285 |
34575a |
|
30 |
7.73a |
21.6 |
37.0 |
2.75 |
47.0 |
37.4 |
63.8 |
16.7 |
55.0 |
0.673 |
3288 |
29276abc |
|
36 |
7.90a |
23.4 |
39.3 |
2.95 |
44.4 |
34.9 |
63.5 |
17.9 |
54.6 |
0.659 |
3266 |
28664bc |
|
40 |
7.68a |
22.1 |
37.7 |
2.78 |
46.8 |
37.4 |
64.0 |
17.2 |
54.3 |
0.670 |
3281 |
30491ab |
|
60 |
7.15b |
21.8 |
37.1 |
2.83 |
47.2 |
37.4 |
63.5 |
17.0 |
54.2 |
0.667 |
3299 |
23940c |
|
LSD (p = 0.10)‡ |
0.41 |
NS§ |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
5340 |
|
Trial mean |
7.61 |
22.3 |
37.9 |
2.83 |
46.3 |
36.7 |
63.8 |
17.2 |
54.5 |
0.667 |
3284 |
29389 |
†Within a column, treatments marked with the same letter are statistically similar (p=0.10); top performer is in bold.
‡LSD; least significant difference at the p=0.10.
§NS; no significant difference between treatments.
Light sensors were placed in between the rows of corn to measure the intensity of light reaching the soil surface, and a control was placed outside of the corn rows. The light intensity, measured in accumulated lumens ft-2, is shown in Figure 2.. This figure provides a visualization of light intensity but does not, however, state that these differences are statistically significant. By mid-July, approximately two months after planting, light intensity was highest in the 60” plot and the control outside of the plots. The amount of light reaching the soil surface was similar between the 36” and 40” plots and between the 20” 30” plots.
Trial 2- The impact of corn row width on silage productivity and establishment of interseeded forages
Interactions
In 2022, there was a significant row spacing by forage type interaction (p=0.033) for percent ground cover just before corn harvest (Figure 3). All three forage types performed best in the 60” rows compared to the 30” and 40” rows. In the 30” rows, alfalfa and the orchardgrass/alfalfa mix had higher ground over than the orchardgrass alone. The inverse of this trend was observed in the 40” rows where the orchardgrass treatment performed better than both the alfalfa and the orchardgrass/alfalfa mix. The orchardgrass alone performed better in the wider 40” and 60” rows, whereas the alfalfa was able to establish better in the narrow 30” rows. These results indicate that different forages react differently to the various row widths, and therefore it is important to continue to study the optimal row spacing for interseeded forage establishment.
Impact of Row Width
There was a significant difference in ground cover, corn harvest population, and corn yield between the row widths (Table 14). The 60” rows had significantly higher ground cover from the interseeded forages, 28.2%, and the 30” and 40” rows had ground cover of only 6.19% and 3.91% respectively. The wider row spacing allows for better establishment of the interseeded crop, but overall, the forage yields were low and therefore not measured. Corn populations at harvest were highest in the 40” rows, 30,774 plants ac-1, and that was statistically greater than the 30” and 60” rows, both of which were below the target population of 30,000 plants ac-1. Corn yield was highest in the 30” rows, 28.0 tons ac-1, and that was significantly more than the other row spacings. Interestingly, the 40” rows had the highest harvest population but the lowest corn yields, 15.9 tons ac-1, which is 1.3 and 1.8 times less than the 30” and 60” rows.
Table 14. Ground cover, corn silage yield and population by row width in Trial 2, Alburgh, VT, 2022.
|
Row Width
|
Ground cover |
Corn population |
Corn yield 35% DM |
|||
| % | plants ac-1 | tons ac-1 | ||||
|
30-in. |
6.19b |
28003b |
28.0a |
|||
|
40-in. |
3.91b |
30774a |
15.9c |
|||
|
60-in. |
28.2a† |
25669b |
21.6b |
|||
|
LSD (p=0.10) ‡ |
4.82 |
2395 |
2.14 |
|||
|
Trial mean |
12.8 |
28149 |
21.9 |
†Within a column, treatments marked with the same letter were statistically similar (p=0.10). Top performers are in bold.
‡LSD –Least significant difference at p=0.10.
Impact of Forage Type
The interseeded forage type had no impact on the ground cover at harvest, corn harvest population, or corn yield (Table 15). All three forage types had low ground cover at the time of corn harvest; the trial average was 12.8%. With the poor establishment observed in this trial, it is not surprising that the interseeded forages had no impact on corn yields at harvest.
Table 15. Ground cover, corn silage yield and population by forage type in Trial 2, Alburgh, VT, 2022.
|
Interseeded forage type
|
Ground cover |
Corn population |
Corn yield, 35% DM |
|||
|
% |
plants ac-1 |
tons ac-1 |
||||
|
Alfalfa |
12.7 |
28373 |
22.3 |
|||
|
Orchardgrass/alfalfa |
10.4 |
27409 |
21.7 |
|||
|
Orchardgrass |
15.2 |
28664 |
21.5 |
|||
|
LSD (p=0.10) ‡ |
NS§ |
NS |
NS |
|||
|
Trial mean |
12.8 |
28149 |
21.9 |
‡LSD –Least significant difference at p=0.10.
§NS- No significant difference at p=0.10.
On-farm research trials to evaluate the effect of row width on corn yields and establishment of interseeded forages
In 2022, statistical analyses were not done on data collected at either on-farm trial location, therefore any differences between treatments cannot be considered statistically significant. At the St. Albans location, corn population and yield were greater in the 30” rows compared to the 60” rows (Table 16). Corn silage in the 30” rows produced 5.5 more tons ac-1 in 2022 than in 60” rows at the same location. The harvest population in 30” rows was 33,106 corn plants ac-1, above the target seeding rate of 30,000 plants ac-1. The harvest population in 60” rows was only 24,829 corn plants ac-1, which is 8,277 less plants ac-1 than the 30” rows and 5,171 plants ac-1 below the target seeding rate. Alfalfa was only harvested in the 60” rows due to poor establishment in the narrower 30” rows. The average dry matter yield of interseeded alfalfa at the time of corn silage harvest was 174 lbs ac-1. Overall, the interseeded alfalfa produced little biomass, but the dry matter yield observed in this year’s trial was comparable to the biomass production of alfalfa interseeded into corn silage in last year’s trial conducted at the Alburgh, VT location.
At the Enosburg, VT location, corn silage yield was slightly higher in the 20” rows (18.8 tons ac-1) than in the 40” rows (18.4 tons ac-1). Harvest populations were also higher in the 20” rows; there was approximately 2,900 more plants ac-1 in the 20” rows (Table 17). The alfalfa interseeded into 20” rows did not establish well and was not measured, but in 40” rows, the dry matter yield of interseeded alfalfa just after corn harvest was 51.2 lbs ac-1.
Table 16. Harvest characteristics of corn silage and alfalfa, St. Albans, VT, 2022.
|
Row width |
Corn silage |
Alfalfa |
|||
|
Harvest population |
Dry matter at harvest |
Yield, 35% DM |
Average height |
Dry matter yield |
|
|
plants ac-1 |
% |
tons ac-1 |
cm |
lbs ac-1 |
|
|
30-in. |
33106 |
39.0 |
29.9 |
-- |
-- |
|
60-in. |
24829 |
37.2 |
24.4 |
14.5 |
174 |
|
Trial mean |
28967 |
38.1 |
27.1 |
N/A |
N/A |
Top performers are in bold.
Table 17. Harvest characteristics of corn silage and alfalfa, Enosburg, VT, 2022.
|
Row width |
Corn silage |
Alfalfa |
||
|
Harvest population |
Yield, harvest moisture |
Average height |
Dry matter yield |
|
|
plants ac-1 |
tons ac-1 |
cm |
lbs ac-1 |
|
|
20-in. |
31218 |
18.8 |
-- |
-- |
|
40-in. |
28314 |
18.4 |
3.9 |
51.2 |
|
Trial mean |
29766 |
18.6 |
N/A |
N/A |
Top performers are in bold.
Interactions
In 2023, there was a significant row spacing by forage type interaction (p=0.0984) for corn silage yield in the replicated trial in Alburgh, VT (Figure 4). Similar trends in corn silage yields were observed in the plots that were interseeded with orchardgrass and the orchardgrass/alfalfa mixture where the 30-inch rows yielded the highest and yields declined in 40- and 60-inch plots. However, corn silage yields remained more constant across the three row spacings when alfalfa was interseeded.
Impact of Row Width
There were significant differences in corn and interseeded forage performance across the row spacing treatments (Table 18). Interseeded forage ground cover, height, and dry matter yield was highest in the 60-inch rows and was significantly higher than the other two spacing treatments which performed similarly to one another. While the significant increase in establishment and growth in the 60-inch rows was expected, these data suggest that increasing row widths from 30 to 40 inches did not provide any benefit to the interseeded forage in that season. It is important to recognize, however, that these assessments were made at the time of corn harvest. These perennial forages would be expected to continue to grow post-harvest and the following spring, at which time a more comprehensive assessment of establishment could be made.
Table 18. Interseeded forage and corn silage performance by row spacing, Alburgh, VT, 2023.
|
Row width |
Ground cover |
Forage height |
Forage yield |
Corn population |
Corn yield, 35% DM |
|
% |
cm |
lbs ac-1 |
plants ac-1 |
tons ac-1 |
|
|
30-in. |
3.75b† |
4.14b |
4.87b |
33707b |
26.4a |
|
40-in. |
3.73b |
5.08b |
13.8b |
34974a |
21.4b |
|
60-in. |
26.2a |
17.9a |
94.6a |
28288c |
22.4b |
|
LSD (p=0.10) ‡ |
7.36 |
4.96 |
39.4 |
1215 |
2.04 |
|
Trial mean |
11.2 |
9.05 |
37.8 |
32323 |
23.4 |
†Within a column, treatments marked with the same letter were statistically similar (p=0.10). Top performers are in bold.
‡LSD –Least significant difference at p=0.10.
Maintaining adequate corn populations while increasing row widths can be a challenge in these systems. In this trial, the populations were over 5,000 and 6,000 plants ac-1 lower in the 60-inch plots compared to the 30- and 40-inch plots respectively. Seeding rates and planting equipment need to be adjusted appropriately to achieve optimal seeding rates at these wider row spacings. In the end, corn silage yields were five- and four-tons ac-1 higher in the 30-inch rows compared to the 40- and 60-inch rows respectively. The fact that the corn populations were lower in the 60-inch rows, but yields were similar to the 40-inch rows suggests that the plants were able to compensate the lower populations.
Similar trends were seen in the on-farm trials (Table 19). For statistical analysis, data from the three locations were combined with the locations serving as replicates. Across the three locations, corn populations and yields were numerically lower but statistically similar in the 60-inch rows compared to the 30-inch rows. Interseeded forage yield, however, was more than 20 times higher in the 60-inch rows and was much higher than the yields obtained in the replicated trial.
Table 19. Interseeded forage yield and corn performance at two row spacings, on-farm, 2023.
|
Row width |
Forage yield |
Corn population |
Corn yield, 35% DM |
|
lbs ac-1 |
plants ac-1 |
tons ac-1 |
|
|
30-in. |
27.6b† |
30368 |
27.3 |
|
60-in. |
644a |
27505 |
25.2 |
|
LSD (p=0.10) ‡ |
531 |
NS§ |
NS |
|
Trial mean |
336 |
28936 |
26.2 |
†Within a column, treatments marked with the same letter were statistically similar (p=0.10). Top performers are in bold.
‡LSD –Least significant difference at p=0.10.
§NS- No significant difference at p=0.10.
The on-farm trial average forage yield at the time of corn harvest was 336 lbs ac-1 which, while still not very substantial, was almost 10 times greater than the average forage yield in the replicated plot trial. These data suggest that increasing corn row spacing can provide better interseeded forage establishment results without significantly compromising corn yields. Spring assessments of the forage stands will provide a better understanding of the final establishment of the forage which will impact the viability of wider adoption of this practice in the future.
Impact of Forage Type
The interseeded forage type had no impact on the ground cover at harvest, corn population, or corn yield (Table 20). All three forage types had low ground cover at the time of corn harvest; the trial average was 11.2%. With overall low growth at that time, it is not surprising that the interseeded forages had no impact on corn yields at harvest. The forage treatments did differ in height and yield at the time of corn harvest. The orchardgrass was the tallest at 12.0cm which was statistically similar to the orchardgrass/alfalfa treatment. The alfalfa alone was the smallest at 5.39 cm. Forage dry matter yield at the time of corn harvest followed the same trend as forage height. Overall, however, forage biomass was extremely low averaging only 37.8 lbs ac-1 across the trial. It is important to recognize, however, that these species could continue to grow post-harvest and the following spring. Establishment was measured at this time to ensure data were collected in the event that corn harvest significantly damaged the forage. However, spring assessments will provide a more comprehensive understanding of forage establishment and survival in this trial.
Table 20. Interseeded forage and corn silage performance by forage type, Alburgh, VT, 2023.
|
Forage type |
Ground cover |
Forage height |
Forage yield |
Corn population |
Corn yield, 35% DM |
|
% |
cm |
lbs ac-1 |
plants ac-1 |
tons ac-1 |
|
|
Alfalfa |
9.71 |
5.39b |
14.4b |
32324 |
23.2 |
|
Orchardgrass |
11.2 |
12.0a† |
67.4a |
32439 |
23.0 |
|
Orchardgrass/Alfalfa |
12.8 |
9.75ab |
31.5ab |
32206 |
24.0 |
|
LSD (p=0.10) ‡ |
NS‡ |
4.96 |
39.4 |
NS |
NS |
|
Trial mean |
11.2 |
9.05 |
37.8 |
32323 |
23.4 |
†Within a column, treatments marked with the same letter were statistically similar (p=0.10). Top performers are in bold.
‡LSD –Least significant difference at p=0.10.
§NS- No significant difference at p=0.10.
Trial 3- The impact of corn row width and population on silage productivity
There were significant differences in harvest populations between treatments (Table 21). The 30”-32,000 plants ac-1 treatment had the greatest harvest population (33,251 plants ac-1) but was not statistically different from the 60”-32,000 plants ac-1 treatment. Harvest populations in the 30”-30,000 plants ac-1 treatment were statistically greater than in the 60”-30,000 plants ac-1 treatment. For the 22-, 25-, and 28,000 plants ac-1 treatments, the harvest populations were not statistically different between the 30” and 60” row width. The trial average dry matter was 45.1% and the average corn yield at 35% dry matter was 22.8 tons ac-1. Despite significant differences in harvest populations, there were no statistical differences in corn yield between treatments.
Table 21. Corn harvest characteristics, Alburgh, VT, 2023.
|
Treatment |
Harvest population |
Dry matter |
Yield, 35% DM |
|
|
|
|
plants ac-1 |
% |
tons ac-1 |
||
|
30 – 22,000 |
21635e† |
45.0 |
28.5 |
||
|
30 – 25,000 |
24974d |
46.4 |
24.1 |
||
|
30 – 28,000 |
28459c |
43.1 |
22.4 |
||
|
30 – 30,000 |
30492b |
45.5 |
20.3 |
||
|
30 – 32,000 |
33251a |
45.2 |
30.0 |
||
|
60 – 22,000 |
22869e |
47.1 |
18.6 |
||
|
60 – 25,000 |
24757d |
42.3 |
19.4 |
||
|
60 – 28,000 |
27951c |
45.5 |
22.5 |
||
|
60 – 30,000 |
27806c |
45.3 |
21.7 |
||
|
60 – 32,000 |
33106a |
45.6 |
20.6 |
||
|
LSD (p=0.10)‡ |
1820 |
NS§ |
NS |
||
|
Trial mean |
27530 |
45.1 |
22.8 |
†Within a column, treatments marked with the same letter are statistically similar (p=0.10); top performer is in bold.
‡LSD; least significant difference at the p=0.10.
§NS; no significant difference between treatments.
Corn quality characteristics are summarized in Table 22. Crude protein, aNDFom, starch, 30-hr uNDFom, 30-hr NDFD, milk per acre, and milk per ton were not statistically different between treatments. ADF was greatest in the 30”-28,000 plants ac-1 treatment, with 28.5%, but this was statistically similar to five other treatments. The 60”-32,000 plants ac-1 treatment had the highest lignin, 3.5%, and was not significantly different from the 30”-28,000 or 60”-25,000 plants ac-1 treatments. NFC was highest in the 30”-25,000 plants ac-1 treatment, 44.3%, but was statistically similar to four other treatments. The 30”-25,000, 60”-22,000, and 60”-28,000 plants ac-1 treatments had the greatest TDN, 63%, and were not statistically different from four other treatments. NEL was highest in the 30”-25,000 plant ac-1 treatment, 0.655 Mcal lb-1, but was statistically similar to five other treatments.
Table 22. Corn quality characteristics, Alburgh, VT, 2023.
|
Treatment |
CP |
ADF |
aNDFom |
Lignin |
NFC |
Starch |
TDN |
30-hr uNDFom |
30-hr NDFD |
NEL |
Milk |
|
|
|
--------------% of DM---------------- |
% of NDF |
Mcal lb-1 |
lbs. ton-1 |
lbs. ac-1 |
|||||||
|
30 – 22,000 |
7.30 |
26.1abc† |
43.7 |
3.10bc |
40.5bcde |
32.7 |
62.3ab |
20.0 |
54.3 |
0.636abc |
3146 |
31356 |
|
30 – 25,000 |
7.87 |
23.2c |
40.1 |
3.00c |
44.3a |
35.7 |
63.0a |
18.8 |
52.9 |
0.655a |
3223 |
27121 |
|
30 – 28,000 |
7.97 |
28.5a |
45.0 |
3.43a |
37.0ef |
27.6 |
61.0c |
21.1 |
53.1 |
0.614cd |
3074 |
24270 |
|
30 – 30,000 |
7.30 |
26.0abc |
43.3 |
3.13bc |
41.4abcd |
33.7 |
62.3ab |
20.5 |
52.6 |
0.639ab |
3141 |
22231 |
|
30 – 32,000 |
7.30 |
24.1bc |
41.1 |
3.07bc |
43.9ab |
35.3 |
62.7a |
18.8 |
54.3 |
0.648ab |
3183 |
33393 |
|
60 – 22,000 |
7.83 |
24.6bc |
41.3 |
3.07bc |
42.3abc |
33.6 |
63.0a |
18.8 |
54.5 |
0.649ab |
3222 |
20950 |
|
60 – 25,000 |
7.57 |
28.3a |
45.9 |
3.33ab |
36.1f |
26.8 |
61.3bc |
21.8 |
53.0 |
0.610d |
3083 |
20873 |
|
60 – 28,000 |
7.90 |
23.8bc |
39.8 |
3.07bc |
43.5abc |
34.6 |
63.0a |
19.4 |
51.2 |
0.654ab |
3227 |
25412 |
|
60 – 30,000 |
7.83 |
26.5ab |
43.7 |
3.13bc |
40.2cde |
31.8 |
62.0abc |
20.8 |
52.4 |
0.631bcd |
3112 |
23589 |
|
60 – 32,000 |
7.77 |
28.2a |
45.3 |
3.50a |
38.3def |
28.3 |
61.3bc |
22.0 |
51.3 |
0.614cd |
3055 |
21995 |
|
LSD (p = 0.10)‡ |
NS§ |
3.16 |
NS |
0.30 |
3.68 |
NS |
1.15 |
NS |
NS |
0.024 |
NS |
NS |
|
Trial mean |
7.66 |
25.9 |
42.9 |
3.18 |
40.8 |
32.0 |
62.2 |
20.2 |
53.0 |
0.635 |
3147 |
25119 |
†Within a column, treatments marked with the same letter are statistically similar (p=0.10); top performer is in bold.
‡LSD; least significant difference at the p=0.10.
§NS; no significant difference between treatments.
Overall, the Solar Corridor System does hold promise in northeastern corn silage systems. Increasing row spacing from the standard 30” rows up to 60” rows did generally result in a significant yield decline. As displayed in Figure 5, the average yield decline we have observed in our experiments has been 4.0 tons per acre. Yield decline compared to 30” in other row spacings was variable. Some of the variation in yield between these row widths was likely due to differing plant populations within the treatment. Our goal was to hold a constant plant population of 30,000 plants per acre regardless of the row width. This was difficult to achieve, especially has the rows became wider and the number of plants in a row was doubled as with the 60” rows. The competition for space and resources within a row also increased, possibly leading to lower yields and quality. As an example, CP was lower in the 60” rows and may be due to increased competition with greater plant numbers in a single row. To better understand optimum plant populations for 60” row production a seeding rate study was conducted. Interestingly, there were no significant yield differences between any of the populations (22,000 up to 32,000 plants per acre) or row widths (30” or 60”). The quality of forage seemed to be maximized at lower seeding rates as likely the ear size was greater contributing to more starch and less digestible fiber. More research needs to be completed to identify plant populations that will maximize yield and quality in 60” rows. More research still needs to be done on selecting hybrids that will perform well at high seeding rates. Flex ear hybrids have the potential to make up for lower populations and still produce adequate yields by increasing ear size when planted at those low seeding rates.
The establishment of forage into the growing corn was successful but was most reliable at the 60” row spacing compared to the 30” row spacing. Orchardgrass alone did not establish well in narrow 30” rows but performed better in wider row widths with increased light availability. Alfalfa established well even in the 30” rows, and there was little difference in dry matter yield between the alfalfa and orchardgrass/alfalfa mix when interseeded into 30” rows. Regardless of forage type, performance was best in the 60” row widths. More research needs to be done on the long-term success of interseeded forages like alfalfa. Through this project we saw minimal biomass produced come fall but did not have the opportunity to look at production of the forage the next season (Images 1 to 4). But if silage yields can be maintained, then farmers can begin to select their interseed cover crops for more targeted benefits.
Education & Outreach Activities and Participation Summary
Participation Summary:
In 2021 one presentation was provided to the Northeast Certified Crop Advisors focused on developing Solar Corridor Systems in Corn Silage. The presentation (webinar) was on December 15th and there were 56 attendees.
A presentation was given at the the Northeast Cover Crop Council Annual Meeting held on March 10th and 11th, 2022. The presentation was focused on developing alternative strategies to grow corn and improve cover crop establishment. There were 38 in the breakout session.
An on-farm Summer Field Day was hosted by one of the collaborating farms in Franklin, VT. There field day was focused on forages and practices to optimize production and quality. The solar corridors and planting forages into corn was highlighted by farmers and researchers. There were 44 attendees.
The Northwest Crop and Soil Annual Field Day was hosted on July 28, 2022 in Alburgh VT. The all day event highlighted the solar corridor trials on the morning research tour. There were 185 attendees.
The No-Till & Cover Crop Conference was hosted in March 2, 2023 in Burlington, VT. The all day event highlighted various cover crop topics. There was a farmer panel focused on cover cropping. Darby, presented on the solar corridor research to an audience of 175.
The Northwest Crop and Soil Annual Field Day was hosted on July 27, 2023 in Alburgh VT. The all day event highlighted took the attendees on a tour of a variety of cover crop research projects and also stopped at the solar corridor trials. There were 226 attendees.
Research reports, factsheets, guides, and webinars are posted on the Northwest Crops and Soils Program website (https://www.uvm.edu/extension/nwcrops), available at events (field days, conferences, workshops, etc.), advertised on social media pages, and uploaded to the Program’s YouTube channel (https://www.youtube.com/user/cropsoilsvteam/)
Research reports were created for each year of the study to summarize results.
Darby, H., I. Krezenski, S. Ziegler. 2022. Integrating Solar Corridors in Corn Silage Production Systems to Meet Agronomic & Conservation Goals. University of Vermont Extension.
Darby, H., I. Krezenski, S. Ziegler. 2023. 2023_Impact_of_Corn_Row_Spacing_on_Interseeded_Forage_Establishment_Report. University of Vermont Extension.
Darby, H., I. Krezenski, S. Ziegler. 2023_Corn_Row_Spacing_x_Population_Trial_report. University of Vermont Extension.
2023_Corn_Row_Spacing_x_Population_Trial_report
A new factsheet focused on solar corridor cropping systems was created: Solar Corridor Cropping Systems Factsheet
The Guide to Interseeding Cover Crops in the Northeast was updated to include a section on solar corridor cropping systems.
Learning Outcomes
Farmers were surveyed following outreach events including the 2023 No-till Cover Crop Conference and the 2022 & 2023 UVM Crop and Soil Annual Field Day. Survey questions were focused on knowledge gained on general cover cropping principles as well as cover cropping practices (established and new). Farmers were also asked to indicate their interest or potential in trying a new cover crop strategy (such as solar corridors).
65 Farmers reported increased knowledge on strategies to improve cover crops.
8 Farmers interested in trying an alternative cover crop strategy.
Project Outcomes
Working with farmers to implement solar corridors has been a exciting process and endeavor; however the practice still requires more research and development before we can expect broader scale adoption. We started with a couple of farmers interested in exploring this practice but actually ended up with several more farmers reaching out curious about this option. Ultimately we ended up working with 5 farmers to implement solar corridors on their farms. On all farms we helped them seed forage crops into their existing corn stands. One of the farmers happened to plant corn in 20 inch rows (versus the standard 30") so he expanded his row width to 40" to see if he could establish forages in this row width. All the farmers were intrigued and motivated around the concept of establishing their forage crop in the corn year. Unfortunately, there were many challenges to work through such as damage to the interseeded forage especially when there was a wet fall during corn harvest. This was the case in 2023, where record rainfall occurred. The stands of forage growing the corn was quite phenomenal but the corn needed to be chopped and ruts and damage were caused to the established forage. In 2022, one farmers actually obtained such a good stand of forage during the corn year he was excited to see how it looked the next spring. In the spring the stand was strong so he left the forage and decided to harvest it. When he went out to the mow the crop, the field was really rough and also rocky. It made it difficult to make hay. He realized that more work needs to be done to the fields (post corn harvest) to make sure the field is level and without rocks. This is all just part of working through a new practice. Overall, all the farmers still feel excited about the practice and we plan to continue to fine tune this practice.
As indicated, the project team and collaborating farmers are already working towards our next solar corridor experiments. We learned from SARE project that solar corridors can be established between corn rows and these solar corridors could be cover crops or even forage crops. Farmers were excited about established a forage crop during the corn year. Ultimately, if the forage established the summer/fall the year before, the yields in the first harvest year could be double or triple that of a traditional spring seeded forage crop. We have proven that forages will establish both in 30", 40" and 60" rows of corn; however now we must focus on perfecting the practice. How do we move this experiment to a more realistic venture. We need to prepare the field as if it will be a hay field, manage the corn and corn harvest to protect the forage crop, and understand situations/settings where the practice will be most successful. This will be the focus of our new projects.
Information Products
- 2022 Integrating Solar Corridors in Corn Silage Production Systems to Meet Agronomic & Conservation Goals
- 2023 Integrating Solar Corridors into Corn Silage Production Systems
- 2023 Corn Row Spacing by Population Trial Report
- Guide to interseeding cover crops into corn systems in the Northeast
- Solar Corridor Cropping Systems
- Impact of Corn Silage Seeding Rate and Variety on Interseeded Cover Crops