Martin L. Battagliaa, Quirine M. Ketteringsa, G. Godwina, Karl J. Czymmeka,b a Nutrient Management Spear Program, b PRODAIRY, Department of Animal Science, Cornell University
Introduction
Conservation tillage practices and incorporation and injection of manure have increased in New York State over the last 20 years. In the future, it is expected that dairy farmers will need to make significant further progress toward no-till practices to minimize soil erosion losses and maximize soil health and carbon sequestration. Compared to surface application of manure, incorporation and injection can reduce ammonia volatilization, odor emissions and nutrient losses, particularly phosphorus (P), in water runoff. However, shallow incorporation of manure with an aerator tool or similar full-width tillage implements, while effective at retaining nitrogen (N) and P (Place et al., 2010), does not meet no-till practice standards as defined by USDA-NRCS. Injection of manure is only compatible with no-till and reduced tillage if low disturbance equipment is used. One central question is: are conservation tillage practices, including no-till planting and zone building, compatible with systems where manure is spring-injected in New York.
Field studies
Two types of studies were conducted on dairy farm fields in western New York. The first study (2012-2013) evaluated the impact of zone tillage depth (0, 7 and 14 inches). This study was completed on one field in 2012 and two fields in 2013. An aerator was used for seedbed preparation. The second study (2014-2016) evaluated three intensities of conservation tillage, including no-tillage, reduced tillage (aerator without zone tillage), and intensified reduced tillage (aerator plus zone tillage at 7 inches depth). This study was conducted on two fields each year.
All fields had a zone tillage and a winter cereal cover cropping history of more than 10 years. Fields were in a dairy rotation of typically 3-4 yr corn alternated with 3-4 yr alfalfa/grass. Liquid manure was used as the primary source of soil fertility. It was injected (6-inch depth; 30 inches between injection bands) in March at a rate of about 13,000 gallons per acre (2012 through 2015) or 8,000 gallons per acre (2016) using a manure injector with chisel and sweep tools (Figure 1). Average total N content in manure ranged from 20 to 25 pounds of N per 1000 gallons. Manure P content ranged from 5 to 11 pounds of P2O5 per 1,000 gallons, while solids content varies from about 5 to 10%.
In both types of studies, zone tillage was performed in late April using an 8 row (30 inch) zone builder with subsoiler shanks and a 20-foot wide aeration tool set at a 15 degree angle pulled in tandem. Corn was planted at 15-inch corn row spacing at a rate between 34,000 and 35,000 seeds per acre between April 30 and May 13. No sidedressing of N was done given practical limitation of 15-inch corn row spacing. Each year, we measured early growth parameters (plant biomass, leaves per plant, stand density, and plant height at V5), and took soil samples at V5 that were analyzed for the pre-sidedress nitrate test (PSNT). At harvest we took corn stalks and analyzed them for the corn stalk nitrate test (CSNT), determined silage yield and dry matter content as well as forage quality parameters including crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF).
Results
Average plant density at V5 ranged between ~31,600 and 32,700 plants per acre (between 90 and 96% of the seeding rate). Reduced tillage and even omitting tillage altogether did not impact early corn silage stand density (Table 1).
In both types of studies, and for all fields, the PSNT-N exceeded 21 ppm NO3-N, indicating sufficient N from manure and soil organic matter mineralization. The PSNT results also indicate no impact of tillage practice or depth on mid-season N availability (Table 1).
Silage yield averaged about 25 tons per acre (at 35% dry matter) in the tillage depth study, with 7.8% CP. In the tillage intensity studies, yields averaged about 23 tons per acre with 7.3% CP. The results should not be compared between the two types of studies as trials were conducted on different fields and across different growing seasons. Tillage depth or intensity did not impact yield or CP content in either of the studies (Table 1).
The CSNT-N ranged between 3,235 and 3,589 ppm NO3-N in the zone tillage depth, and between 2,315 and 2,753 ppm NO3-N in the tillage intensity study, above the 2,000 ppm NO3-N optimum range. Zone tillage depth and different tillage intensities did not impact CSNT-N and both PSNT-N and CSNT-N show N was not limiting plant growth (Table 1).
Conclusions and Implications
All types of tillage systems and depths performed equally well in terms of plant growth, N availability, corn silage yield and quality suggesting that reduced tillage and no-till can both be viable options to more intensive tillage for this farm. Results might be different for fields with limited history of zone building and other efforts to improve soil health. We conclude that at this farm that has made significant efforts to adopt soil health practices, manure injection followed by no-till planting or zone building can sustain yields and conserve N. No-till planting has the additional benefit that it reduces soil disturbance, risk of P runoff, as well as tillage-associated fuel, equipment, and labor costs.
This article is summarized from our peer-reviewed publication: Battaglia, M.L., Ketterings, Q.M., Godwin, G., Czymmek, K.J. 2021. Conservation tillage is compatible with manure injection in corn silage system. Agronomy Journal. https://doi.org/10.1002/agj2.20604 (in press).
Acknowledgements
In memory of Willard DeGolyer, whose dedication to on-farm research inspired us all. This study was funded by the New York Farm Viability Institute (NYFVI), a USDA Conservation Innovation Grant (69-3A75-17-26), supplemented by federal formula funds. We thank the owners and the farm crew for their collaboratively work and dedication to the success of this research over the 5 years where the field studies were conducted. For questions about these results, contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.
Elson Shields, Department of Entomology – Cornell University
When alfalfa snout beetle (ASB) becomes fully established on your farm, its presence cost you $300-$600 per cow annually. The higher producing dairies are hit harder than the lower producing dairies because the higher producing dairies are more reliant on their production of high quality alfalfa and grass forage to maintain their high milk production. This is an unbelievable amount of loss caused by ASB and is ignored by many in the NNY Agribusiness community.
It takes about 10 years for alfalfa snout beetle to become fully established on individual farms after its initial invasion. ASB damage is frequently missed and stand loss is often blamed on winter kill, until there is a massive migration of adults out of a field or someone uses a shovel to dig yellowed plants in the fall and finds the larvae. ASB often kill out the alfalfa on the high spots in the field first, a symptom which should draw attention from the truck windshield driving past. The best time to survey a field/farm for ASB is during October with a shovel to dig and examine yellowing alfalfa plants. At this time of year, ASB larvae are large, white and easy to identify.
ASB is flightless and has a 2-year lifecycle, so movement around the farm is by walking or hitching rides on farm equipment. The practice of cutting an infested alfalfa field and then moving to a non-infested field next to harvest is the most common way ASB is moved around the farm. During 1st harvest, ASB adults can be easily observed on the harvesting equipment. Over the 10 year period, ASB causes more fields to die out from “perceived winter kill”, resulting in less alfalfa to harvest and more required off-farm purchases of replacement protein, so the increasing costs of feeding the cows is spread out over the 10 year period and often overlooked.
The cost of alfalfa snout beetle to the dairy operation is two prong and can be broken down into two different areas.
1) The cost of forage loss from the field loss and the cost of replanting
Alfalfa is an expensive crop to plant with the required PH adjustment for yield, cost of the seed and the cost of land preparation required for good germination and plant stands (~$140/ac). As a general rule in a NNY 3-cut system, the cost of establishing the crop are not covered with the on-farm production of protein until the beginning of the third crop year. If farms cannot keep their alfalfa stands viable through the 3rd and 4th production years, the cost of establishing the stand outweighs the benefit of growing alfalfa. Depending on the speed that ASB eliminates the alfalfa stand, the alfalfa stand could be lost in a single year or over a 2-3 year period with grass filling in the open spaces. In a NNY 3-cut-4-year rotation alfalfa production system, the cost of alfalfa snout beetle killing out the alfalfa stand ranges between $200 and $400 an acre. In a NNY 4-cut-3-year, the cost of alfalfa snout beetle killing out the alfalfa stand ranges between $200 and $500 an acre. These cost estimates are a combination of the loss of crop yield and the cost of re-establishment of the alfalfa field.
2) The cost of purchasing off-farm protein to replace the alfalfa protein which is no longer available on the farm.
A more hidden cost of alfalfa snout beetle is the cost of the increased protein purchases to compensate for the lack of protein produced on the farm due to the loss of alfalfa from ASB damage. The “off farm purchase protein costs” is directly impacted on the farm’s ability to manage the remaining grass in the field for high protein production. Below are presented various scenarios typical of NNY farms impacted by alfalfa field loss from ASB.
Table 1: The cost of extra soy required in the diet when ASB impacts the production of alfalfa on the farm and causes widespread alfalfa stand losses. Estimates are based on the diet of 30% forage and 70% corn silage. While many farmers claim to produce higher quality grass, analysis of grass forage suggests that the 15% and 11% protein cover the common range of grass quality.
% Alfalfa in Stand
15% protein grass
11% protein grass
100
(clear seeded)
100 cow dairy
$9.30/cow/month
$112/cow/year
$11,200/year
$16.80/cow/month
$201/cow/year
$20,100/year
50:50
(alfalfa:grass)
100 cow dairy
$4.70/cow/month
$56.40/cow/year
$5,600/year
$8.40/cow/month
$100.80/cow/year
$8,400/year
***These estimates were provided by Michael Miller, W.H. Miner Institute and Everett Thomas, Oak Point Agronomics
In summary, the cost of additional purchases of soy protein once ASB becomes establish on the farm ranges from $4.70 to $16.80/cow/ month or $56.40 to $200 per cow/year Add to this the cost of losing alfalfa stands and spending money to replant the stands and the cost per cow increases another $200-$500 /year and the loss to the dairy from ASB is significant. In NY, the “rule of thumb” is that it requires 1 acre of forage to support 1 cow. As a result, the cost per acre and cost per cow of forages are often used interchangeably in discussions. This is the reason that money making dairies become under severe financial pressure within 10 years of ASB moving onto the farm.
The Alfalfa Snout Beetle Solution:
Due to the long-term research support by the NNY dairy farmers, NNYADP, NYFVI, state of NY and Cornell University, ASB can be controlled on a farm for many years with a single application of native NY biocontrol nematodes (entomopathogenic) on each field. The cost of this application is in the range of $40-$60 per acre. The presence of ASB on your farm is costing you between $50-$200/year every year and the solution to ASB is a single expense of $40-$60; a one-time expense. To date, nearly 28,000 acres of NNY ASB infested land has been treated for ASB located on >140 farms. In those fields, alfalfa stand life has increased back to 4-6 years compared to the previous ASB ravaged 1-2 years.
NNY farmers who have initiated a program of applying biocontrol nematodes to your farm, please continue because it is saving/making you money to control ASB. In addition, talk to your neighbor about controlling his ASB because your control would be better if your neighbor was not producing millions of ASB to flood into your alfalfa stands.
NNY farmers who have not applied biocontrol nematodes for ASB control are bleeding profits and are spending unnecessary scarce money on purchases of soy protein when they could be growing it themselves. In addition, you are creating a problem for your neighbor who is trying to control this insect and you need to work with your neighbor to control ASB for both of your benefit.
For more information about ASB control with biocontrol nematodes contact:
Mike Hunter, CCE Field Crops Specialist, Phone (315) 788-8450, ext. 266, Email: meh27@cornell.edu
Kitty O’Neal, CCE Field Crops and Soil Specialist, Phone 315 379 9192 ext 253, Email: kitty.oneil@cornell.edu
Joe Lawrence, CCE Dairy Forage Systems Specialist, Phone 315-778-4814, Email: jrl65@cornell.edu
To Purchase Biocontrol Nematodes for your farm, Contact:
John Wallace, Weed Management Extension Specialist, Penn State University
In the coming year(s), Penn State will be leading a regional, SARE-funded project to better understand the agronomic, environmental, and economic challenges that prevent the adoption of cover crop interseeding in field corn. The team is comprised of Penn State and Cornell University researchers and extension educators, the New York State IPM program, and several cooperating Soil and Water Conservation Districts in PA and NY.
Interseeding cover crops early in the corn growing season (i.e., V4-V6) can potentially increase the benefits of cover cropping in growing regions that struggle to establish fall-sown cover crops. Previous studies and on-farm trials in our region have demonstrated the benefits of interseeding with specialized grain drills for improving establishment rates. Best management practices for early interseeding have also been developed for this region, including cover species selection and herbicide management.
However, there has been less documentation of conservation and soil health benefits associated with early interseeding compared to either winter fallow or post-harvest cover crop seeding. Understanding these benefits, and potential management tradeoffs, will help understand the return-on-investment of this practice. Finally, there is a general consensus that early cover crop interseeding works better in certain growing regions and production systems than others. Defining the geographic and agronomic fit for cover crop interseeding is one of our project objectives.
If you are interested in following the project, or participating in on-farm trials, please take a moment to complete this brief anonymous survey (link below). This information will help the projectteam prioritize on-farm trials and extension-outreach programming in the coming year(s).
J. Cummings, K. Wise, and M. Zuefle, NYS Integrated Pest Management Program; E. Smith, M. Hunter, M. Stanyard, A. Gabriel, K. Ganoe, J. Degni, J.L. Putman, K. O’Neil, J.A. Putman, J. Miller, and M. Lund; Cornell Cooperative Extension M. Dorgan, NYS Department of Agriculture and Markets
The soybean cyst nematode (SCN) is the number one pest of concern in U.S. soybean crops, causing an estimated $1.5 billion in annual losses. Considered a ‘silent’ yield-robber, SCN can cause 10-30% yield loss without any obvious, above-ground symptoms. SCN hadn’t been considered a pest of concern for NY soybean growers before it was first confirmed in Cayuga County in 2016. Even then, it wasn’t a priority consideration. However, based on recent findings, NY soybean (and dry bean) growers can no longer afford to ignore this threat.
The NY State Integrated Pest Management Program, in collaboration with Cornell Cooperative Extension field crops specialists, and funded under a grant from USDA-APHIS Plant Protection Act section 7721 administered by NY State Department of Agriculture and Markets, coordinated a statewide SCN survey in 2019 as part of a soybean commodity survey to test 25 fields. This testing revealed an additional six counties with fields positive for SCN. Those results prompted a continuation and expansion of a SCN survey in 2020 with additional funding from the NY Soybean Checkoff dollars to provide testing for 100 fields statewide. The 2020 survey identified an additional 22 counties with fields positive for SCN. These surveys, along with shared observations from individual testing efforts have now confirmed SCN in a total of 30 counties across NYS, and it is safe to assume that SCN will likely be identified in all soybean producing counties in NYS with continued testing in future years.
Figure 1. The progression of confirmation of the soybean cyst nematode throughout NY State. Counties shaded in green had fields tested with negative results, and counties shaded in red have at least one field confirmed positive for soybean cyst nematode. (All testing was conducted by the SCN Diagnostics Laboratory at the University of Missouri in 2019 and 2020)
Now that we know that SCN is here, and is widespread across NYS, what’s next? Unfortunately, eradication is not an option, but reduction and maintenance of low populations is. Management strategies depend on SCN population levels, which can vary significantly from field to field. Regular testing for this nematode will help you determine your best plan of action for management. Fortunately, most of our positive SCN detections have been in the “low” category, but we found four fields with “moderate” levels and one field with “high” levels of SCN. For reference, based on test results (according to University of Missouri SCN Diagnostics Laboratory), “An egg count of <500 eggs is considered low. An egg count of 500-10,000 is considered moderate. An egg count >10,000 is considered high”. Those egg counts are based on what they find in one cup of soil. Finding a field in NYS with an egg count of 20,000 was quite surprising this year, and it translated to measurable yield loss for the grower. This means we can’t afford to ignore this pest, and we need to start actively managing SCN before our “low” results all become “high” results.
Figure 2. Female SCN nematodes produce ‘cysts’ on soybean roots, which contain the eggs (a). These cysts, when dislodged from the roots, are distributed within the soil (b). The cysts contain approximately 200 eggs each (c). (Images courtesy of G. Yan, S. Markel and E. McGawley, via the SCN Coalition)
It’s much easier to stay ahead of this pest than to try to manage high numbers. Fortunately, our number one management strategy is crop rotation. Once you know you have SCN in a field, the worst thing you can do is grow soybeans continuously. We are lucky to have a number of non-host crops available for rotation, including corn, small grains, clover, alfalfa, and forage grasses. Studies have shown that a one-year rotation to corn may result in up to a 50% reduction in SCN populations the following year. The next best option for managing SCN is by selecting and planting SCN-resistant soybean varieties, and rotating those varieties that you plant. More on that later. For dry beans, however, resistance is not an option, and rotation is even more critical. The third management option is the use of nematode-protectant seed treatments. There are a number of these products available, and most have shown promising results. However, those seed treatments will be most cost-effective in situations where there is high SCN pressure. So, for the vast majority of acreage in NY, based on our current survey results, the seed treatments can be an expensive option with limited benefits for many of our growers. But, that may change as SCN testing expands and we find more moderately to highly infested fields. Of course, an integrated pest management (IPM) approach will provide the best management results, by combining all available management tools.
It’s impossible to talk about SCN management without mentioning resistance. I said previously that you should consider selecting and planting SCN-resistant varieties, and that you should rotate those varieties. Unfortunately, SCN has been evolving and developing resistance to the traits most commonly available in commercial soybean varieties for decades. Slowly, SCN has developed different races that can overcome the resistant soybean varieties. This pest is highly adaptable. That’s why it’s important not to plant the same soybean variety, even if it’s labeled as ‘resistant’, in the same field repeatedly. Similar to chemical modes of action (like herbicides), it’s critical to rotate your tools to avoid, or minimize, resistance development. For more information on this topic, please visit the SCN Coalition website, where they have an abundance of resources available on this topic. Luckily, a number of major seed companies have soybean varieties in the pipeline with novel sources of SCN resistance, and we look forward to the new options.
Figure 3. SCN cysts are tiny, but can be seen on soybean roots with or without magnification. Much smaller than nodules, the cysts appear as whitish-yellow specks along the roots. (Images courtesy of G. Tylka via the SCN Coalition)
Moving forward, we hope to continue providing statewide SCN-testing services to growers through funded surveys. Please contact your local Cornell Cooperative Extension specialist if you suspect you might have SCN on your farm. Continued monitoring through testing will help us understand our populations of SCN, to help make the best management decisions. Let’s work together to maintain mostly low to moderate populations of this potentially devastating pest.
Sandra Wayman1, Lisa Kissing Kucek2, Virginia Moore3, Lais Bastos Martins4, Matt Ryan1 1Soil and Crop Sciences Section, SIPS, Cornell University, 2USDA ARS Dairy Forage Research Center, 3currently: NC State University. Feb 2021: Plant Breeding and Genetics Section, Cornell University, 4Crop and Soil Sciences, NC State University.
Legume cover crops have room for improvement Winter annual legume cover crops are essential management tools for organic farmers; they fix nitrogen, improve soil health, and suppress weeds. Winter annual cover crops are planted in the early fall, overwinter, then grow vigorously in the spring and complete their life cycle in the summer. However, many farmers struggle with these cover crops. Poor emergence, low vigor, and winter kill are basic challenges that could be addressed through plant breeding. Unlike cash crops, cover crops have received relatively little attention from plant breeders in the past. Thus, even modest investments in germplasm improvement could return large benefits. The Sustainable Cropping Systems Lab is taking advantage of this opportunity to improve legume cover crops for organic farmers by participating in the national Cover Crop Breeding Network (Fig. 1). Sites across the U.S. are developing cover crop lines best suited to each region. Our goal is to develop new varieties that boost the sustainability of organic farms, using classical plant breeding methods rather than genetic engineering. We are working with three species of winter annual legume cover crops: hairy vetch (Viciavillosa), crimson clover (Trifoliumincarnatum), and winter pea (Pisumsativum) (Fig. 2).
Figure 1. Sites participating in the legume cover crop breeding program.Figure 2. Left, hairy vetch; top right, crimson clover; bottom right, winter pea.
The traits farmers want To inform our breeding efforts, we conducted a national survey of organic and conventional farmers to learn which cover crop traits were important to them (Fig. 3, Wayman et al 2017). We received 417 responses to the survey, and 87% of the respondents reported they used cover crops. Organic farmers reported placing greater value on the ecosystem services from cover crops than did conventional farmers. The top four traits chosen by respondents as important for legume cover crops were nitrogen fixation, winter hardiness, early vigor and establishment, and biomass production (Fig. 3).
Figure 3. Percentage of farmers (organic and conventional together) who rated the given traits for four focus cover crops as “important” or “very important” out of total of five rating levels (“not at all important” to “very important”). Numbers above bars indicate count of farmer respondents for each cover crop and trait. Stars on bars indicate significant differences between conventional and organic farmers for that particular trait and cover crop (chi-square test, * is P < 0.05, *** is P <0.001).
Genetic improvement The steps in developing better cover crop varieties for farmers are 1) create better genotypes through breeding nurseries, and 2) select the best new varieties through advanced line trials. Researchers at different sites in the project are selecting for different legume traits based on their region. In the legume cover crop nurseries planted at Cornell University, we are selecting for winter-hardiness in addition to early-flowering.
We began the breeding program with seeds of hairy vetch, crimson clover, and winter pea from commercially available varieties, lines from worldwide breeding programs, landraces selected by farmers, and PI (plant introduction) lines from the U.S. National Plant Germplasm System Germplasm Resources Information Network (NPGS GRIN) seed bank.
For five seasons, we have planted breeding nurseries of the three legume cover crop species at our Cornell University site. We selected plants based on fall vigor, low winterkill, spring vigor, early maturity, and soft seed. We culled undesirable plants before flowering, and saved seeds from the best plants to replant in the following year. We selected between 2.8% and 4.6% of the hairy vetch individuals across the breeding seasons, and between < 0.01% and 2.8% of crimson clover individuals.
For winter pea, the first year of the breeding program evaluated the performance of accessions from the National Plant Germplasm System. The results informed what material to include in breeding nurseries. For the following three seasons, we planted and selected early generation breeding lines originating from the USDA-ARS Grain Legume Genetics Physiology Research Center in Pullman, WA. The best 0.5 to 1.4% of the winter pea plants were chosen as new breeding lines, based on winter survival and vigor. In 2019, the winter peas experienced severe winter conditions 900 feet above Cornell University’s campus, where almost all the winter peas died from winterkill.
Advanced line trials In the 2018-2019 and 2019-2020 seasons, our breeding lines were tested against commercial varieties in multi-environment advanced line trials. Sites across the country (Fig. 1) grew replicated plots of breeding lines and commercial checks of each legume cover crop species. Each trial grew the legume cover crops alongside triticale to simulate grass-legume cover crop mixes typically grown by farmers. Breeding lines of each crop were compared with commercial check varieties to assess if our breeding program has produced something better than what is currently available to growers on the market. Lines were evaluated for emergence, winter survival, fall and spring vigor, flowering timing, disease, and biomass. The best lines of each species will be tested again in the 2020-2021 season, and performance of these lines will determine variety release and commercialization.
Nursery and advanced line trial performance Testing variety performance is currently underway. An analysis of the advanced line trials will identify if any lines perform well across the U.S., or if certain lines excel in specific regions. Ideally, we would find a few breeding lines performing well across all sites. Such “broadly adapted” lines could be sold as varieties nationwide. If certain lines are excellent in specific regions, however, seed companies are interested in selling lines as “regionally adapted” varieties. In the meantime, data from the breeding nurseries indicated patterns in regional performance. The results suggest different trends among species, which are detailed below.
Hairy vetch We found no hairy vetch line that performed best in both the fall and spring (Kissing Kucek et al. 2019). Instead a tradeoff between fall growth and spring growth was observed. As a result, the breeding program is screening and selecting for vigor at both times of the year, with the goal of finding ideal lines that have the best overall seasonal performance.
Over two seasons and a dozen U.S. sites (Fig. 1), we tested 16 hairy vetch breeding lines and six checks. Breeding lines developed by the Cover Crop Breeding Network beat the commercial check lines in both years. Winning lines, however, differed among sites. Colder northern environments had different winning breeding lines than warmer southern and western sites. Our Cornell University site proved to be an intermediate winter environment compared with the harsh upper Midwest and mild southeast and west. In cold winters like 2018-2019, Cornell University shared winning lines with MN, WI, and NE. In contrast, during warm winters like 2019-2020, NY was more similar to southern and western sites. These results suggest that the best performing lines in NY may vary depending on weather conditions, with warmer years in NY mimicking southern and Mid-Atlantic sites, and colder winters grouping NY with the northern Midwest. To select for resilient lines that can handle variable winter conditions, Cornell University breeding nurseries include material from warm and cold regions of the U.S.
The 2018 hairy vetch line from Cornell University was the second highest seed yielding in our OR trials, demonstrating 25% more seed yield than checks (Hayes and Azevedo, 2019). High seed yield is a very desirable trait for seed growers and seed companies.
Crimson clover Two commercially available varieties of crimson clover, ‘Dixie’ and ‘Linkarus’ were included as checks in our trials. ‘Dixie’ is a variety developed in GA that exhibits high forage biomass production, ability to reseed, and high amounts of hard seed (Hollowell 1953). ‘Linkarus’ is a highly productive winter hardy crimson clover which was developed in Germany. In general, we have seen ‘Dixie’ perform well in the southern locations, while ‘Linkarus’ performs better at northern locations. In the harsh NY winter of 2018-2019, our breeding lines beat both ‘Dixie’ and ‘Linkarus’.
In two seasons, we also evaluated crimson clover breeding lines for biomass production at Cornell University. Biomass production is important for all farmers, who often use crimson clover as a green manure. The crimson clover lines with the highest biomass production were included in the next season’s nursery. At our Cornell University site in 2018, ‘Linkarus’ had the highest biomass production, with 1.5 to 2.9 times more biomass production than ‘Dixie.’ Additionally, to compare top-performing lines from nursery selections at a dozen sites across the country, we tested 13 crimson clover breeding lines and 2 checks over two seasons. In the first season, a soft-seeded MD breeding line produced the most biomass, followed by ‘Linkarus’ and a Cornell University breeding line. In the second season, ‘Dixie’ produced the most biomass, followed by a MD breeding line.
Breeding lines have also been tested for seed yield in OR, where most crimson clover seed is produced. The two checks beat all breeding lines for seed yield (Hayes and Azevedo 2019). As a result, we have increased our focus on selection for seed yield in the crimson clover breeding program.
Winter pea In NY, winter peas have often been challenging for farmers due to poor winter survival. In the 2017-2018 season, 0.5% of plants were selected based on winter survival and vigor. Their seed is currently being increased so they can be included in future advanced line trials. In the 2019-2020 season, our Cornell University site experienced optimal weather to discriminate cold tolerance. Data from 39 new and different genotypes helped us choose the entries with the best potential to be increased for the advanced line trial.
Over two seasons, we tested 21 winter pea lines and five checks in our advanced line trial. In the 2018-2019 season, the winter pea advanced line trials did not survive at Cornell University and in MN due to harsh winter conditions. Southern locations (CA, GA, NC, OR) of the advanced line trials had overall higher biomass production than did the northern locations (MD, MO, NE, WI) in 2018-2019. Across all sites, our breeding lines performed better than the checks. Indeed, one of our breeding lines was in the top five performers across five different locations, showing good potential for release as a variety. Many of our breeding lines performed better than the two commercially available cultivars in the trial.
An additional observation for winter pea is that lines with the highest vigor in fall may have poor biomass production in the spring. This is not uncommon in peas; if the plants grow too much in the fall their exposed above-ground biomass is susceptible to frost damage and winter kill.
Next steps As part of this project, we will release varieties of legume cover crops adapted to specific regions. Our next steps include selecting for high-vigor and improved material in our nurseries, continuing advanced line trials with this new material, planting seed increases, and inviting farmers and seed company representatives to the breeding sites to evaluate the lines. We planted a third year of advanced line trials in 2020, after which we will determine if any lines are consistently high performers and good candidates for variety release.
Cover Crop Breeding Network team member coming to Cornell In February 2021, a Postdoctoral Scholar with the team, Virginia Moore, will join Cornell as an Assistant Professor with SIPS in the Plant Breeding and Genetics Section. Virginia’s program will focus on breeding for sustainable cropping systems. Virginia has been involved in the national Cover Crop Breeding Network as a project manager since 2019. She is currently based at USDA-ARS in Beltsville, MD, and completed her graduate work at the University of Wisconsin, with a MS in Agroecology and Agricultural & Applied Economics and a PhD in Plant Breeding & Plant Genetics. She sees plant breeding as a powerful tool to increase sustainability of cropping systems, with goals like a) reducing pesticide inputs through breeding for pest resistance, b) increasing cover crop adoption by developing regionally adapted cultivars, c) selecting crops for organic systems, and d) diversifying cropping systems through rotations and intercropping. She is excited to continue working in cover crop breeding and to take on new crops including alfalfa and other forages, hemp, and switchgrass.
Acknowledgements: Thanks to Gerald Smith for sharing data and resources. Thanks to Chris Pelzer, Katherine Muller, Dylan Rodgers, James Cagle, Nina Sannes, and Matt Spoth for help planting the nurseries.
References Hayes, R and M. Azevedo. 2019. Seed yield of hairy vetch and crimson clover breeding lines. Raw data available upon request.
Hollowell, E. A. 1953. Registration of varieties and strains of crimson clover (Dixie crimson, Reg. No. 1). Agron. J. 45:318-320
Kissing Kucek, L.; H. Riday; et al. 2019. Environmental influences on the relationship between fall and spring vigor in hairy vetch (Vicia villosa Roth). Crop Science. 59:1-9
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Across the US and within NY, corn rootworm (CRW) is developing resistance to the Bt-RW traits in our GE corn varieties, causing increased root damage and decreasing yields. Yield losses from CRW root feeding can surpass 10% without any above ground symptoms, making this type of losses difficult to detect. In addition, corn grown for silage is more sensitive to yield losses from CRW feeding than corn grown for grain. As CRW resistance increases to Bt-RW, the damage becomes more apparent and easier to detect, but losses have been occurring in the field in prior years, going undetected. Increased damage has been reported in NY for all of the Bt-RW traits regardless of company.
Important points about CRW biology: There are two important points about CRW biology which need to be remembered when managing this pest and reducing its potential for developing resistance to any of our management tools. 1) In NY, all eggs are laid in existing corn fields during August, and 2) if the newly hatch CRW larvae in the spring do not find a corn root, they die. Since CRW eggs are laid in existing corn fields in August of prior year, crop rotation is our best resistance management tool. Since the majority of the corn grown in NY is in rotation with alfalfa for our dairy farms, NY trails the rest of the nation in the development of CRW resistance to Bt-RW.
For our dairy farmers, that grow corn in rotation with alfalfa, corn is typically grown in a field for 3-5 years. The longer corn is grown continuously in a field, the higher risk the field has for economically damaging CRW root feeding and yield losses. After rotating out of a non-corn crop, first year corn does not need any CRW management (or expensive Bt-RW trait costs). A non-Bt-RW corn variety should be planted with a seed corn maggot/wireworm effective seed treatment. This choice in year 1 saves $15-$20 per acre in seed costs. In year 2, the risk of CRW loss increases to 25-30% in NY. To offset this risk, a farmer has several options. Many farmers will assume the risk and plant a non-Bt-RW corn variety without any additional protection such as a soil insecticide. A second option in year 2 is to use either a 50% rate of soil insecticide (if insecticide boxes are available), high rate of neonic seed treatment or an insecticide added to the liquid popup fertilizer. The CRW pressure in year 2 is not high enough to recommend the use of Bt-RW in most cases and the option of an insecticide is often a less expensive route to reduce production costs. The deployment of different modes of toxicity in year 2 from Bt-RW significantly reduces the selection for Bt-RW resistance by CRW. In continuous corn years 3-5, the risk of economic loss from CRW is high enough to merit the use of Bt-RW corn varieties. A second option in years 3-5 of continuous corn is the use of a full rate of soil insecticide, if insecticide boxes are available. Adding insecticide to the popup fertilizer during years 3-5 is not recommended due to unreliable efficacy with the higher CRW populations and increased risk for economic damage.
Strategy 2 for our dairy farmers: Incorporating biocontrol nematodes into their rotation and crop production.
By using the biocontrol nematode technology developed to combat alfalfa snout beetle in NNY, our dairy farmers can reduce their corn seed costs by eliminating the purchase of the Bt-RW traits in their corn varieties. A single inoculation of each field with native persistent NY biocontrol nematodes provides protection from corn rootworm larval feeding by attacking these insects before they damage the corn roots. NY research data indicates a single soil inoculation ($50-$60/acre) establishes these NY adapted biocontrol nematodes in the soil profile for many years, where they attack a wide range of pest soil insects across a wide variety of crops. During the corn years, these biocontrol nematodes attack rootworm larvae and during the alfalfa years, attack wireworms, white grubs, clover root curculio feeding on the alfalfa and grass in the field.
If the biocontrol nematodes are inoculated into the field during the alfalfa portion of the crop rotation, the farmer can use corn varieties without Bt-RW for the entire corn rotation. Biocontrol nematodes take until the second growing season after application to become fully established in the soil profile and when applied to the alfalfa crop, become fully established before corn is planted. If the field is inoculated with biocontrol nematodes during the first year of the corn rotation, the corn variety planted in year 1 can be without the Bt-RW trait because rootworm is never a problem in 1st year corn in NY. By the second year, the biocontrol nematodes are fully established and corn varieties can be planted without Bt-RW for the remaining years of the corn portion of the rotation.
However, if the corn field is inoculated with biocontrol nematodes during the 2nd-4th year when rootworm damage risk is higher, the corn variety planted during the year of inoculation needs to have the Bt-RW trait to provide some additional protection while the biocontrol nematodes become fully established in the field. If the cost of establishing biocontrol nematodes in a field is a one-time cost of $50-60/acre and the Bt-RW trait adds $20/acre/year to the seed costs, the breakeven point for the nematode application is year 3 when the Bt-RW trait is not purchased or used. In the years beyond 3-years after application, the seed cost savings will continue to be the cost of the Bt-RW which is an unnecessary expense.
For our cash grain farmers, an annual rotation of corn and a non-host crop like soybeans completely eliminates the need for any CRW management tools. During the corn years, non Bt-RW corn varieties can be safely planted without risk of losses from CRW. The elimination of the Bt-RW trait in the corn planted reduces the seed cost $15-$20 per acre and the use of a Bt-RW trait is completely unnecessary. However, a seed treatment for seed corn maggot to protect plant emergence is recommended due to our typically wet cold soils. The enhanced adoption of cover crops to protect our soil from erosion and any history of animal manure application significantly increases the risk of plant stand losses from seed corn maggot.
Long-term continuous corn fields: The culture of corn continuously in the same field for multiple years using only Bt-RW to control CRW places tremendous selection pressure for the insect to develop resistance to the Bt-RW toxins. This widespread practice across the corn belt has resulted in the documented CRW resistance to all Bt-RW traits and the insect is causing economic losses for farmers adopting these continuous corn practices. Closer to home, Bt-RW failures have been reported in Central NY corn fields, multiple corn growing areas of Ontario, Canada and to the south in Pennsylvania. With no new technology against CRW available for the next few years, these growers have a real challenge on their hands to minimize losses from this adaptable insect, if these farmers continue with long-term continuous corn production without breaking the CRW cycle with crop rotation. Farmers with fields producing corn continuously for multiple years need to seriously consider working a crop rotation into their farming practices. There are well documented agronomic yield advantages/responses from crop rotation over continuous corn, even without considering the reduction in CRW root feeding damage.
However, if farmers insist on growing continuous corn in field without interruption, there are several issues to consider. The continued use of Bt-RW accelerates CRW resistance and the single field failure becomes the source of highly resistant beetles moving into neighboring fields, causing significant yield losses even in neighboring fields where farmers are utilizing crop rotation to minimize CRW-Bt-RW resistance development and yield losses. The farmer growing continuous corn and producing highly resistant beetles becomes “a neighborhood social problem” for his neighbors. Some farmers add a soil insecticide over the top of the Bt-RW trait, think this is a solution to the resistance issue. While the corn stands better with less damage at the plant base, selection for CRW Bt-RW resistance continues to accelerate within the root system in areas outside of the soil insecticide treated zone.
The addition of biocontrol nematodes to the continuous corn culture is a way of introducing an independent mortality factor to help the Bt-RW trait control rootworm larval populations. However in these high CRW pressure systems, biocontrol nematodes should not be used alone. CRW has developed resistance to every other management strategy used to manage its damage, biocontrol nematodes used alone will also select for CRW resistance. If farmers are interested in incorporating biocontrol nematodes into their continuous corn production, farmers should continue to use varieties with the Bt-RW trait to continue to kill the susceptible CRW larvae or match the use of biocontrol nematodes with a full rate of soil insecticide.
Two types of studies were conducted on dairy farm fields in western New York. The first study (2012-2013) evaluated the impact of zone tillage depth (0, 7 and 14 inches). This study was completed on one field in 2012 and two fields in 2013. An aerator was used for seedbed preparation. The second study (2014-2016) evaluated three intensities of conservation tillage, including no-tillage, reduced tillage (aerator without zone tillage), and intensified reduced tillage (aerator plus zone tillage at 7 inches depth). This study was conducted on two fields each year.![Plant density and pre-sidedress nitrate test (PSNT) at V5, and corn stalk nitrate test (CSNT), silage yield [35% dry matter (DM)], crude protein (CP), and acid and neutral detergent fiber (ADF, NDF).](https://blogs.cornell.edu/whatscroppingup/files/2021/02/Conservation-tillage-Table-1.png)
In memory of Willard DeGolyer, whose dedication to on-farm research inspired us all. This study was funded by the New York Farm Viability Institute (NYFVI), a USDA Conservation Innovation Grant (69-3A75-17-26), supplemented by federal formula funds. We thank the owners and the farm crew for their collaboratively work and dedication to the success of this research over the 5 years where the field studies were conducted. For questions about these results, contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.
