Final report for ONE20-379
Project Information
This SARE project conducted in 2021 and 2022 in northern Vermont evaluated the impact of corn variety and population on cover crop establishment and yields. The study found that seeding rates did not significantly impact yields, and no additional yield benefit was gained by seeding at rates higher than 26,000 seeds ac-1. However, corn variety significantly impacted corn harvest characteristics and yields. Cover crop ground cover was relatively low across the entire trial, indicating that interseeding cover crops into corn silage systems is challenging and may require changes to corn variety selection, populations, and interseeding timing. The project involved two farmers who learned about the challenges of growing cover crops in standing row crops, and the project demonstrated the challenges of interseeding cover crops into standing corn. However, the study indicated that more data needs to be collected to better understand the interaction of corn hybrid characteristics with cover crop management, and additional opportunities need to be explored to achieve consistent establishment and persistence of interseeded cover crops in northern climates. The study's approach and methods were sound, but the outcomes were not what was expected. Weather, herbicides and soil conditions at harvest all play an important role in determining if interseeded cover crops will establish well in northern climates.
Broad Objective. This project sought to support farmers in building sustainable cropping systems while maintaining yields and economic viability.
Objective 1. Identify corn varieties and seeding rates that meet cash crop yield and cover crop biomass goals.
Objective 2. To identify indeterminate corn varieties suitable for Northeast production.
Objective 3. Determine the profitability of the cropping system, calculating the cost of corn seed, cover crop seed, corn yield, cover crop termination (if applicable), and purchased feed (to offset lost corn yield). This information can be used to choose varieties that meet the farmer’s conservation and profitability goals.
Objective 4. Create outreach with farmer-friendly technical reports, factsheets, webinars, and via presentations at field days and the Northeast Cover Crop Council Conference. Over 400 farmers, agribusiness personnel, technical service providers, and other stakeholders will be reached.
Over the years, corn cropping systems have primarily prioritized yields over ideal land stewardship practices. Climate change challenges this system in the Northeast because of the increase in high-intensity rainfalls resulting in an increase in crop failures, soil loss, and nutrient runoff. Implementing conservation practices like cover cropping can build soil health, retain crop nutrients, protect water quality, and stabilize crop yields. Interseeding cover crops is a common way to lengthen the window of opportunity for growth especially in areas with short growing seasons. Although widely adopted, barriers within the corn production system have minimized the successful establishment of interseeded cover crops.
In an attempt to maximize yields, silage corn is planted at denser populations which reduces the amount of sunlight reaching the soil, inhibiting cover crop growth. Corn varieties that perform best at high seeding rates are those promoted by seed companies. As a result, determinate hybrids are the most common type purchased and planted on the landscape. Determinate hybrids have corn ears with a determined maximum size. In contrast, indeterminate or “flex” ear hybrids are not widely advertised or known about by the farming community. Flex hybrids can grow to a larger ear size depending on environmental conditions. As an example if the corn population is reduced a flex hybrid will compensate by increasing ear size whereas the non-flex types will keep the same ear size. Flex hybrids also tend to have an upright leaf architecture. Hence the integration of flex hybrids onto farms may help promote the growth of interseeded cover crops , but research is needed.
This project will provide agronomic knowledge to farmers regarding selecting corn hybrids and cultural practices that best balance obtaining viable yields with the conservation benefits of cover cropping. On-farm research trials will be conducted that examine the attributes of indeterminate ear corn silage varieties by quantifying the impact of corn variety and seeding rates both on cash crop yield, cash crop quality, and cover crop biomass. In addition, the profitability of corn varieties in systems that utilize conservation practices will be calculated by estimating reductions in purchased energy sources, and the offset of yield reductions through increased quality. This will result in innovative data on conservation and profitability in corn cropping systems, and educational and outreach materials. A database, factsheet, and technical report will be developed. This information will be available online and in print at field days, workshops, and conferences.
While this question has not been extensively studied, Northwest Crop and Soils have implemented similar on-farm partnerships in corn cover cropping systems. These past successful studies, outreach, and farmer partnerships will inform the project. The innovative research and outreach materials generated by this project will support farmers in building more sustainable farming systems by providing information that helps farmers reach yield, conservation, and viability goals.
Cooperators
- - Producer
- - Producer
Research
Objectives and Methods:
Objective 1. This objective was to conduct research trials to identify corn varieties and seeding rates that met cash crop yield and cover crop biomass goals. Collaborating farmers willing to conduct the trials had already been identified. Roger Rainville hosted the trial at Borderview Research Farm in Alburgh, and Tim Magnant hosted the trial in one of the most impaired watersheds in the Lake Champlain Basin. Treatments included six different corn varieties (3 determinate and 3 indeterminate varieties) seeded at 26,000 28,000, 30,000, 32,000, 34,000, and 36,000 plants per acre. The main plots were seeding rates, and subplots were variety. Agronomic methods were those commonly used in corn silage systems in the local region. Corn silage varieties were in the same relative maturity range. The project utilized the following corn varieties: For the 2021 crop season, determinant (fixed ear) Pioneer P38N85, Brevant B95V86AM, and Brevant B95M87AMXT. Indeterminate (Flex) ears included Pioneer P9608Q, Brevant B97F86AMXT, DeKalb DKC 44-80RIB. For the 2022 crop season, varieties included determinant (fixed ear) Pioneer P8820Q, Brevant B95M87Q, and Brevant B96V86R. Indeterminate (Flex) ears included Pioneer P9608Q, Brevant B97F87G09AM, DeKalb DKC 8618. Corn was interseeded with a cover crop mix at the V4 to V6 leaf stage at both locations. The cover crop mix was planted at a rate of 26.5 lbs/acre and consisted of annual ryegrass (20 lbs/acre), red clover (5 lbs/acre), and tillage radish (1.5 lbs/acre).
Data collection included taking light infiltration data between cornrows every other week from corn emergence until harvest with a LI-COR LI-191R Line Quantum Sensor. At emergence, corn populations were assessed by counting 17.5” in three rows in each plot. Corn plots were harvested with a tractor and two-row chopper. Yields were weighed with a portable platform scale. A subsample of approximately one pound was taken from each plot to determine dry matter and forage quality. A 10 plant subsample of corn was taken from each plot to determine ear and stalk weights. Cover crop biomass was sampled by clipping biomass from a total of 3 quadrats (1.5 x 1.5ft) per plot. The clipped biomass was sorted by species and weighed to determine inter cover crop competition and weed biomass. To process corn silage samples for analysis, they were ground with a Wiley mill, then ground with a cyclone sample mill (1mm screen) from the UDY Corporation at UVM’s Cereal Testing Lab. Quality was determined with FOSS NIRS (near-infrared reflectance spectroscopy) DS2500 Feed and Forage analyzer. Quality metrics included crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), 30-hour digestible NDF (NDFD), total digestible nutrients (TDN), and Net Energy-Lactation (NEL).
Data analysis involved calculating the general linear model analysis using the general linear model procedure of SAS (SAS Institute, 2008). All treatment factors in this experiment were considered fixed with the exception of replicates. Mean separation among treatments involving variety and seeding rates was obtained using the Least Significant Difference procedure when significant F-tests (P<0.10) were observed
Objective 2. This was to identify indeterminate corn varieties suitable for Northeast production. Dr. Heather Darby worked closely with University of Maine, Cornell University, and Penn State University to develop and host corn variety evaluation trials. The trials were held annually in conjunction with seed companies, nutrition companies, and farmers. Each year, over 200 corn hybrids were evaluated for yield and quality across the region. An analysis of those yearly results was conducted to search for indeterminate (flex ear) corn hybrids that also ranked high for yield and quality. The analysis was composed into a quick reference table that allowed farmers to easily search for varieties that met their agronomic goals and also had indeterminate characteristics. It was housed on UVM’s Northwest Crops and Soils Program website and shared with collaborating programs.
Objective 3. This objective was to determine the profitability of the cropping system. From the farmer's perspective, it was important to determine whether the use of these hybrids in their cropping systems would be profitable. The proposal used the Ohio State University's Enterprise budget tool, which generated a corn silage production budget to calculate the profitability of each of the hybrids used in this project. The tool could be located at https://ag.purdue.edu/commercialag/home/resource/2018/05/corn-silage-production-budget/. The tool utilized inputs including but not limited to; the cost of cash crop seed, fixed costs for cover crop seed and field operations (labor, equipment, and fuel costs for field preparation, planting corn, planting a cover crop, fertility applications (fertilizer and/or manure), weed control (tillage or chemical), and harvest costs. The output from this worksheet provided a clear way to evaluate how these hybrids performed on the trial farms. UVM Extension staff worked with the farmers to complete the spreadsheets and then shared the data with stakeholders.
Objective 4. This objective was to provide educational resources. Results were published in farmer-friendly technical reports, factsheets, and presentations at field days and the Northeast Cover Crop Council Conference. Over 400 farmers, agribusiness personnel, technical service providers, and other stakeholders were reached each year of the grant. See the Outreach section for more detail.
2021 Methods
The field trials were conducted at Borderview Research Farm in Alburgh, VT and at Bridgeman View Farm in Franklin, VT (Table 1). The trials evaluated the impact of corn variety and population on cover crop establishment and corn yields. Six corn varieties were planted at populations ranging from 26,000 to 36,000. Varieties were selected for fixed (F) and flex-ear (FL) characteristics as well as suitability to a northern climate and productivity. Manure was injected at the Franklin site at a rate of 7,159 gal ac-1 on 25-Apr. Corn was planted on 14-May and 17-May for the Alburgh and Franklin locations respectively with the Alburgh site receiving 5 gal ac-1 9-18-9 starter fertilizer at planting. 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 on 14-Jun and 19-Jun in Alburgh and Franklin respectively. Prior to harvest, corn populations were measured by counting the number of plants in the center two rows of each plot in Alburgh and the number of plants within random 17.5’ transects in each plot in Franklin. Corn was harvested on 17-Sep in Alburgh using a John Deere 2-row corn chopper and collected in a wagon fitted with scales to weigh the yield of each plot. In Franklin, the host farmer harvested the trial and weighed each plot using portable truck scales. At both sites, an approximate 1 lb subsample was collected, weighed, dried, and weighed again to determine dry matter content and calculate yield from each plot. The samples 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. Following corn harvest, cover crop ground cover and biomass were assessed on 28-Oct and 29-Oct for the Franklin and Alburgh sites respectively. Cover crop biomass was measured by harvesting the material in a 0.25m2 area in each plot, weighing the material, and taking a subsample to be dried to determine dry matter content. Ground cover provided by the cover crop was measured using the Canopeo smartphone application.
Table 1. Trial management, 2021.
|
Location |
Borderview Research Farm – Alburgh, VT |
Bridgeman View Farm – Franklin, VT |
|
Soil type |
Cabot extremely stony fine sandy loam |
Westbury stony fine sandy loam |
|
Corn variety treatments (relative maturity) |
B95M87AMXT (95 RM) (F) B95V86AM (95 RM) (F) B97F86AMXT (97 RM) (FL) DKC44-80 (94 RM) (F) P38N85 (92 RM) (F) P9608Q (96 RM) (FL) |
B95M87AMXT (95 RM) B95V86AM (95 RM) B97F86AMXT (97 RM) DKC44-80 (94 RM) P38N85 (92 RM) P9608Q (96 RM) |
|
Corn population treatments (seeds ac-1) |
28,000 30,000 32,000 34,000 36,000 |
28,000 31,000 34,000 |
|
Corn planting date |
14-May |
17-May |
|
Cover crop mixture |
25 lbs ac-1 Annual ryegrass (60%) Red clover (30%) Tillage radish (10%) |
25 lbs ac-1 Annual ryegrass (60%) Red clover (30%) Tillage radish (10%) |
|
Cover crop planting date |
14-Jun |
19-Jun |
|
Harvest date |
17-Sep |
23-Sep |
Methods 2022
The field trials were conducted at Borderview Research Farm in Alburgh, VT and at Bridgeman View Farm in Franklin, VT (Table 1). The trials evaluated the impact of corn variety and population on cover crop establishment and corn yields. Six corn varieties were planted at populations ranging from 26,000 to 36,000. Varieties were selected for fixed and flex-ear characteristics as well as suitability to a northern climate and productivity. Manure was injected at the Franklin site at a rate of 7,159 gal ac-1 on 25-Apr. Corn was planted on 13-May at both sites with the Alburgh site receiving 5 gal ac-1 9-18-9 starter fertilizer at planting. 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 on 2-Jul and 22-Jun in Alburgh and Franklin respectively. Prior to harvest, corn populations were measured by counting the number of plants in the center two rows of each plot in Alburgh and the number of plants within random 17.5’ transects in each plot in Franklin. Corn was harvested on 23-Sep in Alburgh using a John Deere 2-row corn chopper and collected in a wagon fitted with scales to weigh the yield of each plot. In Franklin, the host farmer harvested the trial and weighed each plot using portable truck scales on 27-Sep. At both sites, an approximate 1 lb subsample was collected, weighed, dried, and weighed again to determine dry matter content and calculate yield from each plot. The samples 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. Following corn harvest in Alburgh, cover crop ground cover was assessed on 20-Oct using the Canopeo smartphone application. Cover crop biomass was insufficient to warrant collection. In Franklin, the cover crop had established poorly across the trial and, due to very wet weather at harvest, the condition did not allow for cover or biomass measures.
Table 1. Trial management, 2022.
|
Location |
Borderview Research Farm – Alburgh, VT |
Bridgeman View Farm – Franklin, VT |
|
Soil type |
Covington silty clay loam |
Westbury stony fine sandy loam |
|
Corn variety treatments (relative maturity) |
B95M87Q (95 RM) (F) B95V86R (95 RM) (F) B97G09AM (97 RM) (FL) NK8618 (86 RM) (FL) P8820Q (88 RM) (F) P9608Q (96 RM) (FL) |
B95M87Q (95 RM) (F) B95V86R (95 RM) (F) B97G09AM (97 RM) (FL) NK9535 (95 RM) (FL) P8820Q (88 RM) (F) P9608Q (96 RM) (F) |
|
Corn population treatments (seeds ac-1) |
26,000 28,000 30,000 32,000 34,000 36,000 |
24,000 28,000 31,000 34,000 |
|
Corn planting date |
13-May |
13-May |
|
Cover crop mixture |
25 lbs ac-1 Annual ryegrass (60%) Red clover (30%) Tillage radish (10%) |
25 lbs ac-1 Annual ryegrass (60%) Red clover (30%) Tillage radish (10%) |
|
Cover crop planting date |
2-Jul |
22-Jun |
|
Harvest date |
23-Sep |
27-Sep |
Weather Data 2021
Weather data was recorded with a Davis Instrument Vantage Pro2 weather station, equipped with a WeatherLink data logger at each trial site (Tables 2 and 3). Conditions throughout the season were generally hotter and drier than normal although July was cooler than normal. The region experienced drought conditions categorized at “abnormally dry” or “moderate drought” throughout the duration of the trial (Drought.gov). In total precipitation was 6.27 inches and 7.63 inches below normal for May-Sep in Alburgh and Franklin respectively. A total of 2613 and 2494 Growing Degree Days (GDDs) were accumulated during the season in Alburgh and Franklin respectively. These were 64 and 143 more than the 30-year normal for these locations respectively.
Table 2. 2021 weather data for Alburgh, VT.
|
|
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
58.4 |
70.3 |
68.1 |
74.0 |
62.8 |
|
Departure from normal |
-0.03 |
2.81 |
-4.31 |
3.25 |
0.14 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
0.66 |
3.06 |
2.92 |
2.29 |
4.09 |
|
Departure from normal |
-3.10 |
-1.20 |
-1.14 |
-1.25 |
0.42 |
|
|
|
|
|
|
|
|
Growing Degree Days (base 50°F) |
334 |
597 |
561 |
727 |
394 |
|
Departure from normal |
33 |
73 |
-134 |
85 |
7 |
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 3. 2021 weather data for Franklin, VT.
|
|
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
59.6 |
69.3 |
67.6 |
72.1 |
62.9 |
|
Departure from normal |
1.21 |
1.83 |
-4.84 |
1.39 |
0.19 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
0.71 |
2.61 |
2.44 |
2.77 |
2.65 |
|
Departure from normal |
-2.68 |
-1.02 |
-1.78 |
-1.14 |
-1.01 |
|
|
|
|
|
|
|
|
Growing Degree Days (base 50°F) |
298 |
580 |
544 |
685 |
387 |
|
Departure from normal |
6 |
93 |
-86 |
103 |
27 |
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.
Interactions
There were very few significant interactions between main effects (Table 4). A significant interaction between corn seeding rate and variety for corn population was observed at the Alburgh location. This indicates that the varieties produced different populations in response to the same seeding rate treatment (Figure 1). This may be due to varietal differences in seed size and shape which can impact planting accuracy. The interactions between corn seeding rate and variety for cover crop yield and corn crude protein, both observed at the Franklin location, indicate that the varieties’ responses to altered seeding rates changed the effect on cover crop biomass and corn crude protein. Figures 2 and 3 display these interactions. For most varieties, cover crop biomass was highest at the middle seeding rate and decreased at the highest seeding rate. However, varieties DKC44-80 and P38N85 did not follow this trend. This may be due to plant architecture. Corn crude protein response fluctuated with some varieties increasing as seeding rates increased, some decreased as seeding rates increased, and some increased or decreased only at the middle seeding rate. We’d expect flex-ear varieties (B97F86AMXT, DKC44-80, and P9608Q) to contribute to higher protein levels at lower seeding rates as the plants are able to take advantage of limited competition by producing larger ears and therefore higher silage protein. However, this wasn’t true for all flex-ear varieties. Similarly, for fixed-ear varieties we’d expect higher protein levels at higher populations as these varieties are better adapted to these high competition situations and can maintain ear size and therefore silage protein content. Again, not all fixed-ear varieties followed this trend. These data suggest that other varietal performance factors that are impacted by seeding rate may contribute to protein content. The lack of other significant interactions indicates that corn varieties responded similarly in terms of yield and quality parameters when planted at different seeding rates.
Table 4. Significance of main effects and main effect interactions.
|
|
Alburgh location |
Franklin location |
||||
|
|
Seeding rate |
Variety |
Rate x Variety |
Seeding rate |
Variety |
Rate x Variety |
|
Population (seeding rate) |
*** |
** |
* |
*** |
** |
NS‡ |
|
Corn yield |
* |
NS |
NS |
** |
** |
NS |
|
Corn dry matter |
NS |
*** |
NS |
NS |
*** |
NS |
|
Fall ground cover |
NS |
** |
NS |
NS |
NS |
NS |
|
Cover crop yield |
NS |
NS |
NS |
NS |
NS |
** |
|
Ear proportion |
N/A† |
N/A |
N/A |
NS |
NS |
NS |
|
Ryegrass proportion |
N/A |
N/A |
N/A |
NS |
NS |
NS |
|
Radish proportion |
N/A |
N/A |
N/A |
NS |
NS |
NS |
|
Clover proportion |
N/A |
N/A |
N/A |
NS |
NS |
NS |
|
Weeds proportion |
N/A |
N/A |
N/A |
NS |
NS |
NS |
|
Corn crude protein |
NS |
* |
NS |
NS |
*** |
*** |
|
Corn ADF |
NS |
** |
NS |
NS |
NS |
NS |
|
Corn aNDFom |
NS |
** |
NS |
NS |
NS |
NS |
|
Corn lignin |
NS |
NS |
NS |
NS |
NS |
NS |
|
Corn fat |
NS |
NS |
NS |
NS |
NS |
NS |
|
Corn starch |
NS |
** |
NS |
NS |
NS |
NS |
|
Corn uNDF240 |
NS |
*** |
NS |
NS |
NS |
NS |
|
Corn TDN |
NS |
NS |
NS |
NS |
NS |
NS |
|
Corn NEL |
NS |
NS |
NS |
NS |
NS |
NS |
|
Milk yield (lbs ton-1) |
NS |
NS |
NS |
NS |
NS |
NS |
|
Milk yield (lbs ac-1) |
* |
NS |
NS |
* |
** |
NS |
* 0.1 < p > 0.05; ** 0.05 < p > 0.01; *** p < 0.01
†N/A; not measured at that location
‡NS; Not statistically significant
Impact of Corn Seeding Rate
As anticipated, seeding rate significantly impacted corn populations at harvest in both locations (Tables 5 and 6). At the Alburgh location, populations aligned well with the seeding rate treatments leading to significantly different harvest populations between each seeding rate treatment. At the Franklin site, where fewer seeding rates were imposed, populations were significantly higher in the 34,000 seeds ac-1 treatment, however the 31,000 and 28,000 seeds ac-1 treatments ultimately had statistically similar harvest populations around 28,000 plants ac-1. These differences also translated into statistically differing yields at both locations. In Alburgh the highest yield of 22.7 tons ac-1 was obtained from the 36,000 seeds ac-1 treatment. However, this was statistically similar to the 30,000 and 26,000 seeds ac-1 treatments, indicating that no additional yield benefit was gained by seeding at a rate greater than 26,000 seeds ac-1. As discussed in the previous section, there was no significant interaction between ear type (fixed vs flex) and seeding rate for yield indicating that no additional yield benefit was seen increasing seeding rates beyond 26,000 seeds ac-1 for either ear-type. At the Franklin site the highest yield was obtained by the 31,000 seeds ac-1 treatment which yielded 23.7 tons ac-1. As this was statistically similar to the 34,000 seeds ac-1 treatment, no additional yield benefit was gained by seeding above 31,000 seeds ac-1.
Table 5. Corn and cover crop characteristics by seeding rate, Alburgh location.
|
Seeding Rate |
Population |
Corn yield@ 35% DM |
Corn DM |
Ground cover |
Cover crop yield |
|
seeds ac-1 |
plants ac-1 |
tons ac-1 |
% |
% |
DM lbs ac-1 |
|
26000 |
24611f† |
22.6a |
43.9 |
63.6 |
1525 |
|
28000 |
26426e |
20.0c |
45.3 |
62.4 |
1495 |
|
30000 |
27540d |
22.2ab |
46.3 |
61.2 |
1474 |
|
32000 |
30492c |
20.3bc |
46.9 |
64.9 |
1481 |
|
34000 |
32355b |
20.0c |
46.7 |
63.3 |
1822 |
|
36000 |
33565a |
22.7a |
46.8 |
62.4 |
1522 |
|
LSD (p=0.10) ‡ |
676 |
2.11 |
NS¥ |
NS |
NS |
|
Trial mean |
29165 |
21.3 |
46.0 |
63.0 |
1553 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Table 6. Corn characteristics by seeding rate, Franklin location.
|
Seeding Rate |
Population |
Corn yield@ 35% DM |
Corn DM |
Ear proportion |
|
seeds ac-1 |
plants ac-1 |
tons ac-1 |
% |
% |
|
28000 |
27629b |
20.5b† |
49.4 |
47.6 |
|
31000 |
28708b |
23.7a |
50.8 |
47.3 |
|
34000 |
31363a |
21.9ab |
50.5 |
47.9 |
|
LSD (p=0.10) ‡ |
1665 |
2.11 |
NS¥ |
NS |
|
Trial mean |
29234 |
22.0 |
50.2 |
47.6 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
At the Franklin location, plants were also divided into ear and stover fractions. The proportion of the total plant dry matter that was in the ear fraction averaged 47.6% and did not differ by seeding rate treatment. At both sites following corn harvest, cover crop ground cover and biomass were assessed. In Franklin additionally the samples were sorted into ryegrass, radish, clover, and weed fractions. Neither location saw a significant difference in ground cover or cover crop biomass (Tables 5 and 7). Sorting from the Franklin site indicated that the cover crop mixture was dominated by annual ryegrass followed by radish and weeds. Virtually no clover was found. However, this composition did not vary by seeding rate treatment indicating that, even at lower seeding rates, which allow more light to penetrate the corn canopy, a similar cover crop yield and composition could be expected
Table 7. Cover crop characteristics by seeding rate, Franklin location.
|
Seeding Rate |
Ground cover |
Cover crop yield |
Ryegrass |
Radish |
Clover |
Weeds |
|
seeds ac-1 |
% |
DM lbs ac-1 |
% of DM |
|||
|
28000 |
30.0 |
384 |
77.1 |
16.2 |
0.136 |
6.52 |
|
31000 |
33.7 |
468 |
79.2 |
8.92 |
0.166 |
11.7 |
|
34000 |
29.7 |
280 |
89.4 |
7.72 |
0.130 |
2.80 |
|
LSD (p=0.10) ‡ |
NS¥ |
NS |
NS |
NS |
NS |
NS |
|
Trial mean |
31.1 |
378 |
81.9 |
10.9 |
0.144 |
7.02 |
‡LSD; least significant difference at the p=0.10 level.
Top performer indicated in bold.
¥NS; not statistically significant
Table 8. Corn quality characteristics by seeding rate, Alburgh location.
|
Seeding Rate |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
seeds ac-1 |
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
26000 |
8.25 |
20.1 |
36.5 |
2.29 |
38.7 |
65.4 |
0.690 |
9.64 |
58.2 |
3432 |
27158a† |
|
28000 |
8.18 |
19.5 |
35.4 |
2.19 |
39.8 |
65.8 |
0.697 |
9.49 |
57.9 |
3453 |
24128b |
|
30000 |
8.06 |
20.4 |
37.0 |
2.28 |
38.9 |
65.3 |
0.686 |
9.94 |
57.7 |
3397 |
26475ab |
|
32000 |
7.86 |
20.8 |
37.3 |
2.31 |
38.6 |
65.2 |
0.684 |
9.90 |
57.7 |
3391 |
24000b |
|
34000 |
7.83 |
19.5 |
35.3 |
2.19 |
40.7 |
65.7 |
0.695 |
9.39 |
56.9 |
3431 |
24046b |
|
36000 |
7.87 |
20.1 |
36.3 |
2.14 |
40.2 |
65.7 |
0.694 |
9.71 |
57.0 |
3422 |
27200a |
|
LSD (p=0.10) ‡ |
NS¥ |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
2568 |
|
Trial mean |
8.01 |
20.1 |
36.3 |
2.24 |
39.5 |
65.5 |
0.691 |
9.68 |
57.6 |
3421 |
25501 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Table 9. Corn quality characteristics by seeding rate, Franklin location.
|
Seeding Rate |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
seeds ac-1 |
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
28000 |
8.13 |
19.6 |
35.5 |
2.19 |
38.6 |
67.0 |
0.711 |
11.1 |
56.3 |
3496 |
25094b† |
|
31000 |
8.19 |
20.0 |
36.2 |
2.23 |
38.3 |
66.5 |
0.704 |
10.0 |
57.4 |
3471 |
28725a |
|
34000 |
8.07 |
19.7 |
35.4 |
2.25 |
38.9 |
66.8 |
0.707 |
11.0 |
56.0 |
3468 |
26624ab |
|
LSD (p=0.10) ‡ |
NS¥ |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
2629 |
|
Trial mean |
8.13 |
19.7 |
35.7 |
2.22 |
38.6 |
66.8 |
0.707 |
10.7 |
56.6 |
3478 |
26815 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Impact of Corn Variety
Corn variety significantly impacted corn harvest characteristics at both locations (Tables 10 and 11). At both sites, variety P38N85 produced one of the lowest populations. This could be due to differences in seed size and shape, complicating accurate planting in comparison to the other varieties. Corn yield varied significantly by variety at only the Franklin site. Variety DKC44-80 was the top yielder at both locations. This was statistically similar to four other varieties at the Franklin site. At both sites variety P38N85 was the lowest yielding which matches the trend observed in harvest populations. Corn dry matter content also varied across varieties at both locations. In Alburgh, all varieties had dry matter contents around 45% except for P38N85 which was significantly higher at 49.9%. This indicates that this variety matured earlier than the other varieties at this location. This also is to be expected as P38N85 has the shortest relative maturity in the trial.
Table 10. Corn and cover crop characteristics by variety, Alburgh location.
|
Variety |
Population |
Corn yield@ 35% DM |
Corn DM |
Ground cover |
Cover crop yield |
|
|
plants ac-1 |
tons ac-1 |
% |
% |
DM lbs ac-1 |
|
B95M87AMXT (F) |
29693a† |
21.0 |
45.6a |
58.0c |
1311 |
|
B95V86AM (F) |
28314c |
20.9 |
46.0a |
65.1ab |
1580 |
|
B97F86AMXT (FL) |
29379ab |
21.1 |
44.7a |
59.6bc |
1573 |
|
DKC44-80 (FL) |
29064ab |
22.8 |
44.7a |
70.2a |
1898 |
|
P38N85 (F) |
28919bc |
20.2 |
49.9b |
59.2bc |
1579 |
|
P9608Q (FL) |
29621a |
21.8 |
45.0a |
65.9ab |
1378 |
|
LSD (p=0.10) ‡ |
676 |
NS¥ |
2.25 |
6.77 |
NS |
|
Trial mean |
29165 |
21.3 |
46.0 |
63.0 |
1553 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
In Franklin, variety B97F86AMXT had a dry matter content of 46.3% which was significantly lower than the other varieties that were all above 50%. B97F86AMXT had the longest relative maturity in the trial. Overall, these dry matter contents are significantly higher than the target of 35%. Extreme drought conditions throughout the season likely contributed to expedited maturation and dry down prior to being able to harvest the trials. In Franklin, corn plants were also separated into ear and stover fractions. The proportion of the plant allocated to the ear fraction did not differ significantly between varieties, averaging 47.6% of the total dry matter.
Table 11. Corn characteristics by variety, Franklin location.
|
Variety |
Population |
Corn yield@ 35% DM |
Corn DM |
Ear proportion |
|
|
plants ac-1 |
tons ac-1 |
% |
% |
|
B95M87AMXT (F) |
30865a† |
19.4b |
50.5b |
50.6 |
|
B95V86AM (F) |
29206a |
22.2ab |
50.3b |
49.1 |
|
B97F86AMXT (FL) |
30036a |
22.6a |
46.3a |
44.9 |
|
DKC44-80 (FL) |
28708a |
24.7a |
50.0b |
48.4 |
|
P38N85 (F) |
25721b |
19.5b |
53.6c |
47.4 |
|
P9608Q (FL) |
30865a |
23.8a |
50.5b |
45.4 |
|
LSD (p=0.10) ‡ |
2355 |
2.98 |
2.07 |
NS¥ |
|
Trial mean |
29234 |
22.0 |
50.2 |
47.6 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Post-harvest ground cover varied across varieties only at the Alburgh site (Table 10). The highest ground cover of 70.2% was observed in plots with variety DKC44-80. This was statistically similar to two other varieties. This higher ground cover led to almost 1 ton ac-1 dry matter biomass but was not statistically different from the other varieties. Ground cover and biomass were substantially lower at the Franklin site and did not vary across varieties (Table 12). Composition of the cover crop was dominated by annual ryegrass followed by radish and weeds. Virtually no clover biomass was found. The composition of the cover crop did not vary across the different varieties.
Table 12. Cover crop characteristics by variety, Franklin location.
|
Variety |
Ground cover |
Cover crop yield |
Ryegrass |
Radish |
Clover |
Weeds |
|
|
% |
DM lbs ac-1 |
% of DM |
|||
|
B95M87AMXT (F) |
29.5 |
346 |
86.7 |
10.0 |
0.133 |
3.13 |
|
B95V86AM (F) |
34.6 |
414 |
92.0 |
7.62 |
0.000 |
0.329 |
|
B97F86AMXT (FL) |
42.1 |
320 |
94.0 |
2.57 |
0.000 |
3.43 |
|
DKC44-80 (FL) |
19.4 |
354 |
74.3 |
6.75 |
0.630 |
18.3 |
|
P38N85 (F) |
36.5 |
484 |
62.5 |
24.5 |
0.074 |
12.9 |
|
P9608Q (FL) |
24.8 |
346 |
81.8 |
14.2 |
0.028 |
3.94 |
|
LSD (p=0.10) ‡ |
NS¥ |
NS |
NS |
NS |
NS |
NS |
|
Trial mean |
31.1 |
378 |
81.9 |
10.9 |
0.144 |
7.02 |
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Corn variety did significantly impact some corn quality parameters at both sites (Tables 13 and 14). Crude protein levels were significantly lower in varieties DKC44-80 and B95V86AM at both sites. At the Alburgh site, ADF, aNDFom, Starch, and 240-hr uNDF also varied significantly. Variety B95V86AM, despite the lower protein content, had significantly lower ADF and aNDFom contents and had significantly higher starch. Despite these differences in single quality parameters, the predicted milk yields per ton of corn silage, which combines multiple quality characteristics into one metric, did not vary across varieties. The significant differences in milk yield per acres at the Franklin site are due to the significant differences in yield per acre, not quality parameters.
Table 13. Corn quality characteristics by variety, Alburgh location.
|
Variety |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
|
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
B95M87AMXT |
7.91b† |
21.0bc |
38.2b |
2.27 |
38.1cd |
65.3 |
0.684 |
10.2d |
57.5 |
3380 |
24849 |
|
B95V86AM |
7.88b |
18.9a |
34.4a |
2.20 |
41.6a |
65.4 |
0.697 |
8.97ab |
57.5 |
3431 |
25106 |
|
B97F86AMXT |
7.99b |
20.2abc |
36.6ab |
2.24 |
39.0bcd |
65.8 |
0.694 |
9.97cd |
58.0 |
3437 |
25339 |
|
DKC44-80 |
7.86b |
19.0a |
34.6a |
2.11 |
41.4ab |
65.8 |
0.697 |
8.87a |
57.9 |
3444 |
27438 |
|
P38N85 |
8.06ab |
21.6c |
38.5b |
2.33 |
37.1d |
65.0 |
0.678 |
10.5d |
57.3 |
3383 |
23889 |
|
P9608Q |
8.36a |
19.6ab |
35.5a |
2.26 |
39.7abc |
65.8 |
0.696 |
9.54bc |
57.2 |
3452 |
26387 |
|
LSD (p=0.10) ‡ |
0.307 |
1.58 |
2.50 |
NS¥ |
2.52 |
NS |
NS |
0.627 |
NS |
NS |
NS |
|
Trial mean |
8.01 |
20.1 |
36.3 |
2.24 |
39.5 |
65.5 |
0.691 |
9.68 |
57.6 |
3421 |
25501 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Table 14. Corn quality characteristics by variety, Franklin location.
|
Variety |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
|
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
B95M87AMXT |
8.32a† |
19.5 |
35.2 |
2.17 |
39.0 |
67.2 |
0.713 |
10.7 |
57.1 |
3505 |
23818cd |
|
B95V86AM |
7.80c |
20.4 |
36.7 |
2.20 |
38.7 |
66.0 |
0.696 |
11.1 |
55.7 |
3408 |
26424bcd |
|
B97F86AMXT |
8.45a |
19.1 |
34.7 |
2.23 |
38.8 |
66.7 |
0.708 |
8.88 |
57.9 |
3476 |
27509abc |
|
DKC44-80 |
7.82c |
19.3 |
35.2 |
2.18 |
39.1 |
67.0 |
0.711 |
10.8 |
56.2 |
3497 |
30250a |
|
P38N85 |
8.03b |
20.3 |
36.8 |
2.22 |
37.8 |
67.0 |
0.705 |
11.8 |
55.3 |
3467 |
23641d |
|
P9608Q |
8.35a |
19.7 |
35.8 |
2.33 |
38.0 |
66.8 |
0.711 |
10.9 |
57.2 |
3517 |
29245ab |
|
LSD (p=0.10) ‡ |
0.190 |
NS¥ |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
3718 |
|
Trial mean |
8.13 |
19.7 |
35.7 |
2.22 |
38.6 |
66.8 |
0.707 |
10.7 |
56.6 |
3478 |
26815 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Figure 4 shows corn and cover crop yields by variety for the Alburgh location. For interseeding to be an acceptable and widely adopted practice, corn yields and cover crop yields must both be supported simultaneously. Some varieties may possess characteristics which make them more suitable for use in a system that utilizes interseeding. For example, variety DKC44-80 supported both high cover crop yield of almost 1 ton ac-1 while also supporting the highest corn yield of almost 23 tons ac-1. Conversely, while variety P38N85 supported high cover crop yields, is came at the expense of corn yield which was only 20 tons ac-1.
Results and Discussion 2021
Interseeding cover crops into corn silage systems is challenging and may have higher success given changes to corn variety selection, populations, and the timing of interseeding. Determining the best combination of characteristics that support high yielding corn crops and successful cover crops requires multiple years of data to better understand how these variables interact under varying conditions. More data needs to be collected to better understand the interaction of these corn hybrid characteristics with crop management.
Weather Data 2022
Table 2. 2022 weather data for Alburgh, VT.
|
|
May |
Jun |
Jul |
Aug |
Sep |
|
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 |
3.00 |
4.94 |
4.40 |
|
Departure from normal |
-0.40 |
3.93 |
-1.06 |
1.40 |
0.73 |
|
|
|
|
|
|
|
|
Growing Degree Days (base 50°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 3. 2022 weather data for Franklin, VT.
|
|
May |
Jun |
Jul |
Aug |
Sep |
|
Average temperature (°F) |
59.6 |
63.9 |
70.1 |
70.0 |
59.7 |
|
Departure from normal |
1.19 |
-3.58 |
-2.28 |
-0.70 |
-2.96 |
|
|
|
|
|
|
|
|
Precipitation (inches) |
4.53 |
5.08 |
4.71 |
5.17 |
7.01 |
|
Departure from normal |
0.77 |
0.82 |
0.65 |
1.63 |
3.34 |
|
|
|
|
|
|
|
|
Growing Degree Days (base 50°F) |
383 |
429 |
620 |
609 |
332 |
|
Departure from normal |
81 |
-95 |
-74 |
-32 |
-55 |
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.
There were no statistically significant interactions between variety and seeding rate for any of the measures at the Alburgh location. This indicates that the varieties responded similarly, in terms of population, yield, and subsequent cover crop ground cover, as seeding rates were altered. This was unexpected as the varieties selected for this trial included both flex and fixed ear characteristics. Fixed ear varieties tend to produce similarly sized ears regardless of seeding rate and therefore yields are maximized at higher populations. Conversely, flex ear varieties can compensate for lower populations by producing larger ears thus producing higher yields at lower populations than fixed ear varieties. The lack of an interaction suggests that this was not observed in this trial.
Impact of Corn Seeding Rate
As anticipated, seeding rate significantly impacted corn populations at harvest (Table 4). Populations overall were lower than intended across the treatments. This led to some of the seeding rate treatments having similar populations at harvest. Despite this, yields did not differ significantly across seeding rates ranging from 18.2 to 20.5 tons ac-1. This indicates that no additional yield benefit was gained by seeding at rates higher than 26,000 seeds ac-1. As discussed in the previous section, there was no significant interaction between ear type (fixed vs flex) and seeding rate for yield indicating that no additional yield benefit was seen increasing seeding rates beyond 26,000 seeds ac-1 for either ear-type. Altering corn seeding rates could potentially help support better cover crop establishment and growth by allowing more light to infiltrate through the canopy. However, in this trial this was not the case as no statistical difference was observed in cover crop ground cover across the seeding rates.
Table 4. Corn and cover crop characteristics by seeding rate, Alburgh location.
|
Seeding Rate |
Population |
Corn yield@ 35% DM |
Ground cover |
|
seeds ac-1 |
plants ac-1 |
tons ac-1 |
% |
|
26000 |
20873d† |
18.4 |
7.88 |
|
28000 |
21054d |
18.2 |
7.42 |
|
30000 |
23758c |
19.5 |
5.43 |
|
32000 |
25646b |
18.4 |
4.51 |
|
34000 |
26771ab |
20.5 |
5.33 |
|
36000 |
27661a |
19.9 |
2.84 |
|
LSD (p=0.10) ‡ |
1500 |
NS¥ |
NS |
|
Trial mean |
24294 |
19.1 |
5.57 |
†Treatments that share a letter performed statistically similarly to one another.
Top performing treatment indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Table 5. Corn characteristics by seeding rate, Franklin location.
|
Seeding Rate |
Population |
Corn yield@ 35% DM |
|
seeds ac-1 |
plants ac-1 |
tons ac-1 |
|
24000 |
27961 |
12.2 |
|
28000 |
26219 |
19.6 |
|
31000 |
30948 |
18.2 |
|
34000 |
32276 |
19.5 |
|
Trial mean |
29351 |
17.9 |
At the Franklin location, populations tracked similarly to seeding rate treatments except for the 24,000 seeds ac-1 treatment which produced 27961 plants ac-1. This suggests challenges at planting with obtaining the intended rates. Yields were also similar for all seeding rate treatments except for the lowest rate of 24,000 which only yielded 12.2 tons ac-1.
Corn quality characteristics were measured only at the Franklin location and were not analyzed statistically. However, the data suggested that the seeding rates did not impact corn quality (Table 6). The only parameter that significantly differed numerically was milk yield per acre where the lowest seeding rate produced approximately 34% less than the next highest seeding rate. This is due to the difference in corn yield observed between the seeding rates, not forage quality differences. Although some of the varieties included in the trial possessed flex-ear characteristics which would allow them to form larger ears at lower populations, these did not translate into significant impacts on corn silage quality parameters.
Table 6. Corn quality characteristics by seeding rate, Franklin location.
|
Seeding Rate |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
seeds ac-1 |
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
24000 |
8.53 |
20.0 |
35.6 |
2.50 |
39.7 |
64.0 |
0.680 |
8.57 |
57.8 |
3367 |
14396 |
|
28000 |
8.68 |
19.8 |
35.3 |
2.63 |
39.7 |
63.8 |
0.675 |
8.48 |
59.3 |
3369 |
23108 |
|
31000 |
8.48 |
19.8 |
35.1 |
2.67 |
40.7 |
64.0 |
0.681 |
8.11 |
58.2 |
3392 |
21653 |
|
34000 |
8.43 |
19.1 |
34.1 |
2.55 |
41.6 |
63.5 |
0.677 |
8.10 |
57.3 |
3348 |
22803 |
|
Trial mean |
8.55 |
19.7 |
35.1 |
2.60 |
40.3 |
63.8 |
0.678 |
8.32 |
58.3 |
3372 |
21089 |
Top performing treatments indicated in bold.
Impact of Corn Variety
Corn variety significantly impacted corn harvest characteristics at the Alburgh location (Table 7). Varieties NK8618 and P8820Q had significantly lower harvest populations than the other four varieties which all performed similarly to one another. Yields ranged from 16.4 tons ac-1 to 21.8 tons ac-1. The highest yields were observed from variety B97G09AM which was statistically similar to two other varieties. Varieties did not significantly differ in subsequent cover crop ground cover which was relatively low across the entire trial.
At the Franklin site (Table 8) harvest populations were approximately 4000 plants lower for variety P8820Q compared to B95M870 which had the highest populations. Variety B95M870 produced the highest yield of 20.3 tons ac-1, almost two tons more than the next highest variety.
Table 7. Corn and cover crop characteristics by variety, Alburgh location.
|
Variety |
Population |
Corn yield@ 35% DM |
Ground cover |
|
|
plants ac-1 |
tons ac-1 |
% |
|
B95M87Q |
25446a† |
20.2ab |
2.73 |
|
B95V86R |
25337a |
18.3bc |
9.73 |
|
B97G09AM |
25537a |
21.8a |
3.90 |
|
NK8618 |
19965c |
17.1c |
7.20 |
|
P8820Q |
23758b |
16.4c |
5.78 |
|
P9608Q |
25719a |
21.0a |
4.06 |
|
LSD (p=0.10) ‡ |
1500 |
1.92 |
NS¥ |
|
Trial mean |
24294 |
19.1 |
5.57 |
†Treatments that share a letter performed statistically similarly to one another.
Top performing variety indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Table 8. Corn characteristics by variety, Franklin location.
|
Variety |
Population |
Corn yield@ 35% DM |
|
|
plants ac-1 |
tons ac-1 |
|
B95M870 (F) |
30865 |
20.3 |
|
B95V86R (F) |
29870 |
16.5 |
|
B97G09AM (FL) |
28376 |
18.5 |
|
NK9535 (FL) |
29745 |
17.2 |
|
P8820Q (F) |
26758 |
16.7 |
|
P9608Q (FL) |
30492 |
17.7 |
|
Trial mean |
24294 |
19.1 |
Corn variety likely impacted some corn quality parameters at the Franklin site (Table 9). Crude protein levels ranged from 8.28% to 9.10% and were highest in the variety P8820Q. Additionally, 240-hr uNDF and 30-hr NDFD differed between some varieties. The 240-hr uNDF, which represents material left undigested by the animal after 240 hours of exposure to rumen fluid, ranged from 7.94% to 9.28% with the lowest levels observed in variety P8820Q. The 30-hr NDF digestibility ranged from 56% to 59.7% with the highest level observed in variety B95V86R. Little difference was observed in predicted milk yield per ton of dry matter, however, due to differences in yield per acre, predicted milk yield per acre ranged from 19617 to 24028 lbs ac-1.
Table 9. Corn quality characteristics by seeding rate, Franklin location.
|
Seeding Rate |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
seeds ac-1 |
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
28000 |
8.13 |
19.6 |
35.5 |
2.19 |
38.6 |
67.0 |
0.711 |
11.1 |
56.3 |
3496 |
25094b† |
|
31000 |
8.19 |
20.0 |
36.2 |
2.23 |
38.3 |
66.5 |
0.704 |
10.0 |
57.4 |
3471 |
28725a |
|
34000 |
8.07 |
19.7 |
35.4 |
2.25 |
38.9 |
66.8 |
0.707 |
11.0 |
56.0 |
3468 |
26624ab |
|
LSD (p=0.10) ‡ |
NS¥ |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
NS |
2629 |
|
Trial mean |
8.13 |
19.7 |
35.7 |
2.22 |
38.6 |
66.8 |
0.707 |
10.7 |
56.6 |
3478 |
26815 |
†Treatments that share a letter performed statistically similarly to one another.
Top performer indicated in bold.
‡LSD; least significant difference at the p=0.10 level.
¥NS; not statistically significant
Table 10. Corn quality characteristics by variety, Franklin location.
|
Variety |
CP |
ADF |
aNDFom |
Lignin |
Starch |
TDN |
NEL |
240-hr uNDF |
30-hr NDFD |
Milk yield |
|
|
|
% of DM |
Mcal lb-1 |
% of NDF |
lbs ton-1 |
lbs ac-1 |
||||||
|
B95M870 (F) |
8.48 |
20.5 |
36.4 |
2.53 |
39.5 |
64.2 |
0.678 |
8.33 |
57.6 |
3383 |
24028 |
|
B95V86R (F) |
8.60 |
18.8 |
34.1 |
2.73 |
41.0 |
63.7 |
0.683 |
8.05 |
59.7 |
3407 |
19689 |
|
B97G09AM (FL) |
8.38 |
20.1 |
35.2 |
2.65 |
40.2 |
63.7 |
0.675 |
8.12 |
59.0 |
3375 |
21895 |
|
NK9535 (FL) |
8.54 |
20.7 |
36.1 |
2.50 |
39.9 |
64.2 |
0.680 |
9.28 |
56.0 |
3354 |
20204 |
|
P8820Q (F) |
9.10 |
19.0 |
34.3 |
2.64 |
40.4 |
63.4 |
0.675 |
7.94 |
58.6 |
3363 |
19617 |
|
P9608Q (FL) |
8.28 |
19.2 |
34.5 |
2.55 |
40.9 |
63.8 |
0.676 |
8.28 |
58.8 |
3344 |
20707 |
|
Trial mean |
8.55 |
19.7 |
35.1 |
2.60 |
40.3 |
63.8 |
0.678 |
8.32 |
58.3 |
3372 |
21089 |
DISCUSSION
Interseeding cover crops into corn silage systems is challenging and may have higher success given changes to corn variety selection, populations, and the timing of interseeding. Determining the best combination of characteristics that support high yielding corn crops and successful cover crops requires multiple years of data to better understand how these variables interact under varying conditions. More data needs to be collected to better understand the interaction of these corn hybrid characteristics with crop management.
When looking at light infiltration rates over the growing season there is very little difference in our project based on seeding population. In Graph 1., the light can penetrate slightly better at 28,000 seed rate than at 34,000 or 38,000 seeds per acre. However, this advantage is almost totally negated by 17 days after interseeding which is when some cover crop species are just emerging from the soil. Graph 2. shows the data gathered on light infiltration over time in typical corn plots. The graph indicates that the amount of light which reaches the soil surface which is critical to cover crop establishment decreases rapidly from June 16th to July 14th. This is a contributing factor in why cover crops in standing corn are difficult to establish.
Graph 1. Light Infiltration Rate by Seeding Rate
Graph 2. Light Infiltration Rate Over Time.
For the 2021 crop year it did not appear that the determinant vs. indeterminant corn varieties contributed to a statistically significant difference in cover crop biomass. This could have been due to the drought conditions preventing any cover crops from growing well during the corn growing season. All the corn varieties performed similarly with some loss of yield at the lowest population counts. The varieties with the shorter relative maturity dates also yielded less in some cases.
For the 2022 crop year it did not appear that the determinant vs. indeterminant corn varieties contributed to a statistically significant difference in cover crop biomass. This could have been due to weather conditions throughout the crop season, it was significantly drier at the Alburgh location during July which is a critical time for getting cover crops established. At the Franklin location it was significantly cooler throughout the growing season. At the Alburgh location the lowest seeding population did produce a slightly higher percent of ground cover (7.88) than did the rest of the trials at higher populations. In the Franklin location the conditions were so wet the cover crop was destroyed during harvest and could not be assessed. The data did not trend the same for yields between the two sites so it is difficult to make conclusive statements about effects of the different varieties of corn used in the project.
The overall objective of this project was to look at determinant vs. indeterminant ear corn varieties to see if we could reduce populations and still maintain yields, quality, and provide a better environment for cover crops to establish in. The results of this project did indicate that you can maintain yields and quality at lower populations than the industry standard of 32,000-34,000 plants per acre. For our project there were not statistically different yields observed above a seeding rate of 26,000 seeds per acre. While this could provide the farmer with some savings on seed costs, in our work it did not lead to significantly better cover crop establishment. Weather and other variables such as herbicide applications/timing are likely significantly impacting the ability of the cover crop to establish and persist through the end of the growing season. The results for this project were positive in the sense that over the course of this project it was demonstrated that a producer can lower populations (26,000-30,000 plants/acre) and optimize yields. We were however not able to demonstrate a significant increase in cover crop biomass by doing this. We will continue to work on interseeded cover crops, and being able to demonstrate that lower populations do not necessarily impact yields or quality will be good information to bring to cooperators.
Education & Outreach Activities and Participation Summary
Participation Summary:
The NWCS Program has a well-established and extensive outreach program. Technical reports dating back to 2012 are available on the Program’s website. The Annual Field day draws over 225 attendees. The Program’s YouTube channel has over 300 videos with 2400 subscribers and 937,915 views. NWCS has several webinar series that focuses on tile drainage, cover crops, and no-till. Other educational efforts the NWCS has engaged in include courses for Custom Manure Applicator Certification, Required Agricultural Practices for Small Farm Operations, and an Agricultural and Water Quality Curriculum for high school technical centers. Hence the project team has vast experience and networks to distribute the project information locally, regionally, and nationally.
The information developed through this on-farm research was delivered to farmers and other stakeholders through a diverse mix-media outreach program. The outreach materials that developed included:
- a technical report that documents research results in a farmer friendly format;
- a factsheet focused on corn variety selection and profitability analysis for successful cover crops;
- a quick reference table that highlights the yield and quality of indeterminate corn hybrids available in the Northeast;
- a 3 part webinar series focused on modifying corn practices (including variety, herbicide management, and population) for cover crop success.
In addition to outreach materials a field days were held at the Magnant farm to highlight project results and other cover crop and corn strategies for the northeast. The on farm field days were held in Franklin during June of 2021 and August 0f 2022.. The UVM Crop and Soil Annual Field Day (held at Borderview Farm in late July of 2022) also highlighted the project results and allowed farmers to observe corn and cover crop strategies. We estimate that over 400 stakeholders were reached through these events.
As applicable, materials will be 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/)
UVM hosted a field day at the Franklin location on August 7th 2021. The flyer for the event can be viewed 2021SummerFarmMtgFlyer
UVM hosted a field day at the Franklin location on June 17th 2022. The flyer for the event can be viewed 2022_Summer_Dairy_TMagnants_FINAL_061722
UVM hosted a field day in Alburgh on July 28th 2022. The flyer for the event can be viewed 2022_Annual_Field_Day_Flyer2
UVM hosted a field day on a farm in Franklin on October 20th 2022. The flyer for the event can be viewed 2022FallFarmMtgFlyer
UVM Extension created a factsheet to provide growers with a list of indeterminant ear hybrids suitable for use in the northeast. SARE flex ear corn project corn variety fact sheet.
UVM Extension created a factsheet to provide grower with costs estimates associated with growing corn at different populations. The fact sheet can be viewed here.
UVM Extension participated the 2021 Northeast Cover Crop Council and presented on research projects including this on. The agenda for this meeting can be seen here: NECCC-Agenda-2021
Learning Outcomes
Farmers faced with later harvest windows due to climate change have begun to inquire about interseeding as an alternative to post harvest cover crop seeding. Farmers have reported the ability to introduce more species into the mixes and meet government contact requirements as reasons for trying to utilize interseeded cover crops. Farmers also have begun to settle on lower seeding rates as a way to have some money on seed while not sacrificing yields. As farmers become more aware of the importance of the social importance of putting conservation practices in place, especially ones that are as visual as cover crops, they are looking for different ways to get it done consistently year after year. This project is part of a greater body of work in which researchers and farmers are working together to "figure out" how to make cover crops work consistently. With regard to the work of this project the farmers report that they are very interested in the timing of the interseeded cover crops and the advantages it has from a time management perspective but are better understanding the limitation of interseeded cover crops surrounding the weather and herbicide interactions. Farmers are willing to remain engaged in this work moving forward.
Project Outcomes
The work of this project highlighted the importance of a good working relation with the cooperating farmers and even though the original outcome of the project of documenting improved cover crop stands based on reduced corn populations with flexed vs. fixed ear corn varieties was not observed in this project, the farmers learned how challenging growing cover crops in a standing row crop can be. The farmers were included in the the project and felt that the information regarding yields based on populations was useful and will be used in future decision making processes. This project also brought stakeholders together after COVID restrictions were lifted and gave the farming community something to talk about at in-person meetings. This project was the beginning of on-farm field days again for our team which was a very good outcome. This project demonstrated how challenging interseeded cover crops can be to establish in northern climates and how much work left there is to be done.
This project's approach and methods were on target for sound practical applied research. The outcomes, however, were not what we expected. The influence of the type of corn grown doesn't seem to have an effect on the yields, quality, or cover crop establishment. The original idea of being able to significantly lower the seeding populations and maintain yields by growing a "flex" ear corn vs. a "fixed" ear corn did not materialize in a statistically significant manner. We did however demonstrate that lower populations produce similar yields to higher population in a corn silage system with the varieties we had selected for this project. The hope of the project was to be able to reduce the population of corn low enough to allow more sunlight to reach the soil surface longer to benefit cover crop establishment. This did not materialize as the lower populations did not significantly delay the canopy from developing over the space between the rows. This still presents a challenge to interseeding cover crops. From our results we did not find that the type of ear, fixed or flex ,will impact the cover crop establishment or yields significantly. We do feel that seed populations can be reduced from what is typically recommended (34,000-36,000 seeds/acre) to 30,000 plus or minus 2,000 seeds/acre and not see a decrease in yield or quality. This project also demonstrated that cover crops need significantly more light than what a 10,000 seed population change will provide. Another opportunity to look at this issue could be the leaf structure of the plant. This is problematic as seed suppliers don't make this information readily available to the grower to be able to select for those traits. Another option to explore is the opportunities in varieties and species of cover crops seeds. There is much work being done in this area right now but we need to focus on interseeding in particular because this provides the longest growing opportunity for the cover crop. The farmers, agronomists, and seed suppliers need to continue to work together to find a way to get consistent establishment and persistence of interseeded cover crops in northern climates.