S1085: Cover Crops for Sustainable Southern Agroecosystems

(Multistate Research Project)

Status: Active

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SAES-422 Reports

Annual/Termination Reports:

[09/08/2021] [09/08/2022] [10/23/2023]

Date of Annual Report: 09/08/2021

Report Information

Annual Meeting Dates: 07/06/2021 - 07/07/2021
Period the Report Covers: 07/01/2020 - 06/30/2021

Participants

Basinger, Nicholas (nicholas.basinger@uga.edu) – University of Georgia
Chase, Carlene (cachase@ufl.edu) – University of Florida
Devkota, Pratap (pdevkota@ufl.edu) – University of Florida
Eivazi, Frieda (representing John Yang, yangj@lincolnu.edu) – Lincoln University
Fultz, Lisa (lfultz@agcenter.lsu.edu) – Louisiana State University
Fryer, Matthew (mfryer@uaex.edu) – Arkansas Cooperative Extension (University of Arkansas)
Gamble, Audrey (avg0001@auburn.edu) – Auburn University
Haramoto, Erin (erin.haramoto@uky.edu) – University of Kentucky
Maltais-Landry, Gabriel (maltaislandryg@ufl.edu) – University of Florida
Mowrer, Jake (jake.mowrer@tamu.edu) – Texas AgriLife Research
Mulvaney, Mike (m.mulvaney@ufl.edu) – University of Florida
Narayanan, Sruthi (skutty@clemson.edu) – Clemson University
Rajan, Nithya (nrajan@tamu.edu) – Texas AgriLife Research
Reiter, Mark (mreiter@vt.edu) – Virginia Polytechnic Institute and State University (VA Tech)
Ruiz-Menjivar, Jorge (jorgerm@ufl.edu) – University of Florida
Sharma, Lakesh (lakesh.sharma@ufl.edu) – University of Florida
Swisher, Mickie (mesw@ufl.edu) – University of Florida
Sykes, Virginia (vsykes@utk.edu) – University of Tennessee
Temu, Vitalis (vtemu@vsu.edu) – Virginia State University

Brief Summary of Minutes

The meeting was held on July 6 and 7, 2021 at the Crowne Plaza Hotel in Baton Rouge, LA as part of the summer board meeting of the Southern Cover Crop Council (SCCC). On July 6 the meeting focused on the process of data verification for the SCCC Cover Crop Species Selector Tool. The tool will be based on the Northeast Cover Crop Council’s (NECCC) tool and thus the discussion was led by Victoria Ackroyd from the NECCC. Input was provided on distinct cover crop species as well as cover crop groups that should be included in the Selector Tool. Potential and up-and-coming cover crops were also suggested for inclusion.

On July 7, Carlene Chase introduced the objectives of the multi-state cover crop hatch project. There are 5 objectives, and each objective has a leader. Dr. Chase presented the report for Objective 1 (Identify a common set of biological and economic measures that can be applied across crop and cover crop combinations throughout the region to generate a region-wide database), which was prepared by Jake Mowrer. The Objective 1 team is planning to look at various soil health indicators, assess their value, and rank the indices. The team will also focus on undergraduate and graduate training. Objective 1 team identified 3 stakeholder groups that should be considered when selecting appropriate soil health indicators: researchers, service labs, and producers. The team is currently working on a review paper on the applicability of soil health indices to the southeastern region.

Audrey Gamble presented the report for Objective 2 [Select and evaluate summer and winter cover crop germplasm for regional adaptability and determine the appropriate timing of planting, seeding rates, utilization of cover crop goods (includes grazing), and termination to optimize benefits without adversely affecting cash crop cycles]. Dr. Gamble presented results from two multi-state trials on seeding rates for cool-season grain cover crops and cool-season legume cover crops that were conducted as part of this objective. The team will repeat the cool-season legume trial evaluation in Fall 2021.

Mike Mulvaney presented the report for Objective 3 (Assess the influence of cover crops on soil moisture, nutrient cycling, and soil microbiology). Objective 3 team is meeting at quarterly intervals and leveraging results from ongoing cover crop projects. The Objective 3 team categorized ongoing research into different groups involving nutrient cycling, soil moisture, soil microbiology, and crop rotations. The team is planning to continue the meetings and leveraging activities.

Carlene Chase presented the report for Objective 4 (Characterize cover crop efficacy for enhancing cropping system resilience to weeds, pests, and plant pathogens). An update was provided for two studies: (1) a national USDA-NIFA-funded study aimed at elucidating the effect of cover crop termination timing on pests, diseases, and corn performance and (2) developing seeding rate recommendations for US-1136, US-1137, and US-1138 cowpea cover crop germplasm lines. Cowpea biomass production, weed suppression, and resistance to root-knot nematode infestation will be assessed in summer 2021.

Mickie Swisher and Jorge Ruiz-Menjivar provided the report for Objective 5 (Generate an economic database that researchers, technical advisors, and farmers can use to assess the short and long-term economic outcomes of cover crop use). The team submitted a USDA AFRI proposal that was not funded. This team is also working on a manuscript and developing a questionnaire on the adoption of cover crops and economic indicators. The team is planning to expand Grower Think Tank participation to farmers in other states who are involved in on-farm trials.

The reports were followed by a planning discussion for the 2021-22 cool season cover crop study to be led by Audrey Gamble. This will be a repetition of the study that was conducted in 2019-20. Very few locations performed the study in 2020-21 due to the COVID-19 pandemic. In Fall 2021, more locations will be added based on interest from SCCC members and Hatch project participants. Discussion involved seeding rates, planter selection, experimental design, plot size and data collection details. Closing remarks were given by the USDA NIFA representatives, Vance Owens and Mathieu Ngouajio.

Accomplishments

Objective 1: Concepts have been proposed for (1) grouping soil health indices by soil property evaluated (not just biological indicators, but also physical and chemical) and (2) assessing the value of each relevant soil health indicator based on stakeholder group affected. An authorship team has been formed to prepare a review manuscript on the applicability of soil health indices to the southeastern region. A full outline has been prepared, and several pages of content and Alabama soil quality test data have been contributed. Plans for the upcoming year include seeking soil health-specific funding opportunities as an objective team.   Objective 2: Cover crops can create sustainable crop production systems while protecting soil and water resources. Evaluation of cover crop germplasm across multiple locations is useful to harness the full potential of cover crops to provide sought benefits. A meeting was held on August 3, 2021, to discuss potential projects related to germplasm evaluation for cover crops in the southern US region. Collaborators in nine states signed up to participate in a multi-state trial to evaluate winter legume cover crop species and seeding rates. This study will assess productivity and adaptability of winter legume cover crops and will be used to develop site-specific recommendations for legume cover crop management.    Objective 3: The team was able to leverage ongoing research for this objective. There are a number of ongoing experiments in participating states where cover crops are being evaluated for its impact on soil moisture, nutrient cycling, and soil microbiology. Depending on the location and the type of cover crop used, varying responses were found. For example, in an ongoing experiment at College Station, TX, winter cover crops were found to have a significant effect on soil moisture and nutrient turnover in the subsequent cash crop season. The team has several graduate students working on the projects related to Objective 3.  Team members are also actively seeking external grants to address goals related to Objective 3. An in-person field day was hosted by M. Fryer on infiltration measurement training and cover crop field day on April 25, 2021.   Objective 4: The first year of a national study to elucidate the effect of cover crop termination timing on pests, diseases, and corn performance is ongoing with 5 southern states participating. In summer 2020 multiplication of cowpea seeds of the germplasm lines US-1136, US-1137, and US-1138 was conducted in Florida to provide seeds for the multistate study in summer 2021. A preliminary trial was conducted in Florida in summer 2020 with the 3 germplasm lines to aid in designing the protocol for the multistate study. A preproposal was submitted to the Southern SARE Resesrach and Education Grants program in 2020 to fund the study but it was not invited for a full proposal. Despite this, interest is high, and the 2021 study will be conducted in 8 states and Puerto Rico. Seed multiplication will be repeated in summer 2021 to allow for a repeat of the study in summer 2022.     Objective 5: We gave a presentation to the Cover Crop Council Managers titled, “Stakeholder-driven adaptive research: bringing farmers into the research team”, that introduced to them the breadth of stakeholder driven adaptive research methods our team utilizes. We presented about stakeholder-driven adaptive research focusing on research assessments at the 2021 Northeast Cover Crop Council Conference and will host sessions with other cover crop councils over the next two years. We will build upon our work in the PSA project (https://precisionsustainableag.org/) over the next two years with the following activities. We will recruit an advisory panel consisting of 5-8 members. The panel will identify research needs, next steps for stakeholder-driven research, barriers to cover crop adoption, and strategies to increase adoption of cover crops. We will conduct three small focus groups (4-5 people per group) to identify possible reasons why farmers reject using cover crops. Group 1 represents governmental organizations. Group 2 represents suppliers (cover crop seed producers, cover crop councils, equipment suppliers). Group 3 represents farmers (adopters, non-adopters, dis-adopters). We will analyze their feedback to develop questionnaire or interview instruments. We will facilitate farmer-to-farmer networking sessions to identify challenges amongst cover crop users and research needed to address those issues and develop solutions. Research and Extension faculty will be invited to these sessions to learn from the farmers and develop connections. We will promote on-farm research and seek to identify farmers who want to engage in on-farm research with research and extension faculty in their states.

Publications

Aryal, P. and C.A. Chase. 2021. Optimizing weed management with US-1136, US-1137, and US-1138 cowpea cover crop lines. Southern Weed Science Society Meeting (Poster).   Blount, A.R., M. Wallau, E. Rios, J.M.B. Vendramini, J.C.B. Dubeux, M.A. Babar, K.E. Kenworthy, M.J. Mulvaney, K.H. Quesenberry. 2020. 2020 Cool-Season Forage Variety Recommendations for Florida. UF/IFAS Electronic Delivery Information System (EDIS). University of Florida, Gainesville, FL. https://edis.ifas.ufl.edu/pdffiles/AA/AA26600.pdf.   Dareus, R., J.P. Acharya, D.R. Paudel, C.H. Lopes De Souza, B. Tome Gouveia, C.A. Chase, P. DiGennaro, M.J. Mulvaney, R. Koenig, and E.F. Rios. 2021. Phenotypic diversity for phenological and agronomic traits in the UC-Riverside cowpea (Vigna unguiculata L. Walp) mini-core collection. Crop Science.  https://doi.org/10.1002/csc2.20544.   Dareus, R., A.C. Mota Porto, M. Bogale, P. DiGennaro, C.A. Chase, and E.F. Rios. 2021. Resistance to Meloidogyne enterolobii and Meloidogyne incognita in cultivated and wild cowpea. HortScience 56 (4):460-468. https://doi.org/10.21273/HORTSCI15564-20   Devkota, P., M.J. Mulvaney, D.L. Wright. 2021.Terminating Cover Crops Effectively for Weed Suppression. UF/IFAS Electronic Delivery Information System (EDIS). University of Florida, Gainesville, FL. https://edis.ifas.ufl.edu/publication/AG449   Li, J., X. Zhao, G. Maltais-Landry, and B.R. Paudel. 2021. Dynamics of soil nitrogen availability following sunn hemp residue incorporation in organic strawberry production systems. HortScience, 56(2), 138-146. https://doi.org/10.21273/HORTSCI15374-20

Impact Statements

Our participants are contributing the development of a cover crop selector tool and to developing and refining region-specific cover crop recommendations.

Date of Annual Report: 09/08/2022

Report Information

Annual Meeting Dates: 06/29/2022 - 06/30/2022
Period the Report Covers: 07/01/2021 - 06/30/2022

Participants

Brief Summary of Minutes

The meeting was held on June 29 and 30, 2022 as part of the summer board meeting of the Southern Cover Crop Council (SCCC) in Lexington, KY. Outreach activities were discussed on June 29 at the University of Kentucky’s Pirri Equine Teaching Pavilion at North Farm. The outreach objective was addressed on June 29. An update was provided on the progress that had been made on data verification for the SCCC Cover Crop Species Selector Tool and what remains to be done. Plans for a grower video project were finalized and GoPro cameras were distributed to participants who committed to recruiting a grower in their state. Plans were made to develop a webpage with sample videos and a GoPro video protocol.

The research review meeting was conducted on June 30 and was held at the meeting room of the Hyatt Regency Lexington. Meeting started with an introduction of all project participants. Dr. Vitalis Temu moderated the meeting. Meeting started with remarks from the NIFA representatives, Dr. Mathieu Ngouajio and Dr. Bisoondat Macoon. This was followed by objective report presentations. Audrey Gamble presented the report for Objective 2 [Select and evaluate summer and winter cover crop germplasm for regional adaptability and determine the appropriate timing of planting, seeding rates, utilization of cover crop goods (includes grazing), and termination to optimize benefits without adversely affecting cash crop cycles]. Dr. Gamble presented results from two multi-state trials on seeding rates for cool-season grain cover crops and cool-season legume cover crops that were conducted as part of this objective.

Nithya Rajan presented the report for Objective 3 [Assess the influence of cover crops on soil moisture, nutrient cycling, and soil microbiology]. As the new leader of Objective 3, Dr. Rajan proposed ideas for continuing activities under objective 3. Some of the research ideas that were proposed for pursuing external grants included cover cropping strategies in regions where raised beds are common in row cropping systems. Another idea that was presented was putting together a review article on the influence of cover crops on soil moisture, nutrient cycling, and soil microbiology. The team is planning to continue the meetings and leveraging activities.

Carlene Chase presented the report for Objective 4 [Characterize cover crop efficacy for enhancing cropping system resilience to weeds, pests, and plant pathogens]. An update was provided for two studies: (1) a national USDA-NIFA-funded study aimed at elucidating the effect of cover crop termination timing on pests, diseases, and corn performance and (2) developing seeding rate recommendations for US-1136, US-1137, and US-1138 cowpea cover crop germplasm lines. Cowpea biomass production, weed suppression, and resistance to root-knot nematode infestation will be assessed again in summer 2022.

Dr. Jake Mowrer presented the report for Objective 1 [Identify a common set of biological and economic measures that can be applied across crop and cover crop combinations throughout the region to generate a region-wide database]. The Objective 1 team is looking at various soil health indicators and economic indicators of soil health. The team is planning to rank critical biological, chemical, and physical properties which are indicators of soil health based on stakeholder feedback and discussions. Team is also discussing various other activities including proposals, white papers, and a review paper.

Mickie Swisher and Jorge Ruiz-Menjivar presented objective 5 report [Generate an economic database that researchers, technical advisors, and farmers can use to assess the short and long-term economic outcomes of cover crop use]. The team provided an update on their ongoing think tanks, grower meetings, and outreach programs.

The meeting was wrapped up with a discussion about future multistate trials and planning activities for grant proposals and journal articles. Meeting was adjourned at 3.00 PM.

Accomplishments

Objective 1:   Concepts have been proposed for (1) grouping soil health indices by soil property evaluated (not just biological indicators, but also physical and chemical) and (2) assessing the value of each relevant soil health indicator based on stakeholder group affected. An authorship team has been formed to prepare a review manuscript on the applicability of soil health indices to the southeastern region. Plans for the upcoming year include seeking soil health-specific funding opportunities as an objective team. Other ongoing writing projects include an Extension article and an opinion article.   Objective 2:   Cover crops can create sustainable crop production systems while protecting soil and water resources. Evaluation of cover crop germplasm across multiple locations is useful to harness the full potential of cover crops to provide sought benefits. Collaborators in ten states participated in a multi-state trial to evaluate winter legume cover crop species and seeding rates from 2019-2022. This study assesses productivity and adaptability of winter legume cover crops (i.e., crimson clover, berseem cover, hairy vetch, common vetch, winter pea) and will be used to develop site-specific recommendations for legume cover crop management.   Objective 3:   The team continued to leverage ongoing research for this objective. There are a number of ongoing experiments in participating states where cover crops are being evaluated for its impact on soil moisture, nutrient cycling, and soil microbiology. Depending on the location and the type of cover crop used, varying responses were found. The team has several graduate students working on the projects related to Objective 3.  Team members are also actively seeking external grants to address goals related to Objective 3.   Objective 4:   The second year of a national study to elucidate the effect of rye cover crop termination timing on pests, diseases, and corn performance in a no-till corn-soybean rotation is ongoing with 5 southern states participating. Results from the first year indicate that the effects of termination time on cover crop biomass, weed suppression, and corn root rot severity varied by location. In several states where significant effects were observed, post-plant cover crop termination decreased weed infestation at corn V5 stage but tended to increase seedling root rot severity.   An evaluation of cowpea germplasm lines US-1136, US-1137, and US-1138 was conducted in summer 2021 in seven states (Alabama, Florida, Georgia, Kentucky, Louisiana, Texas, and Virginia) plus Puerto Rico. The objectives were to (1) determine the lowest seeding rates for each germplasm line that provide maximum cover crop biomass production and weed suppression, (2) determine the termination dates that optimize cover crop shoot biomass and nitrogen credits, and (3) evaluate the host status of US-1136, US-1137, and US-1138 to plant-parasitic nematodes under field conditions. Averaged over location, cowpea shoot biomass increased in a quadratic manner as seeding rate increased from 40 to 120 lb/ac. Shoot biomass with the three lines did not differ at 6 and 8 weeks after planting (WAP) but US-1136 and US-1138 had higher biomass than US-1137 at 10 WAP. Compared to the nontreated weedy control, all cowpea rates significantly suppressed weed biomass. Seed multiplication was repeated in Florida in summer 2021 to allow for a repeat of the study in summer 2022.    Objective 5:   The team is continuing the development of farmer think tanks and conducting grower field assessments to guide their work. They have recruited five more growers for the think tank this year, as before each from a different state. The most recent discussion included a lengthy analysis of the ability of cover crops to “bank” nitrogen and potash for a cash crop following a cover crop. The main conclusion reached was that meaningful reductions in N and K application can be achieved, but not over the short term. They have developed on-line versions of both the grower field assessments and the think tanks and have offered them to other Hatch team members. Farmers in the most recent field assessment have suggested that the team maintain the virtual venue because it is more cost effective in terms of both time and money for growers and for the research team. A team from the University of Florida (UF; Colleges of Liberal Arts and Agricultural and Life Sciences) is working on the revisions of a manuscript titled “Knowledge mapping of the extant literature on the environmental impacts of cover crops—A scientometric study.” The paper is in its second-round revisions (“minor revisions” in the last round), and we expect this manuscript to be accepted this Fall. The publication outlet is Environments (Q1 Scopus CiteScore: 5.2). Dr. Ruiz-Menjivar is conducting an overarching study that seeks to examine factors influencing farmer adoption of cover crop adoption using the “Theory of Planned Behavior (TPB)”. Collaborators include researchers at the Center for Public Issues Education at UF for this activity. As of 30 August 2022, they have collected responses from 51 farmers in Florida. Farmers are recruited through various organizations, including the Florida Farm Bureau, National Women in Agriculture Association-Florida Chapter, Florida Black Farmers and Agriculturalists Association, Florida Organic Farmers, and Farmworker Association of Florida. Approval to conduct research with human subjects has been obtained: IRB protocol IRB#202102640. The team is planning to work on the analysis and manuscript preparation based on this work in the Spring of 2023.

Publications

Aryal, P., C.A. Chase, and G. Maltais-Landry. 2021. Developing recommendations for US-1136, US-1137, and US-1138 cowpea germplasm lines for use as cover crops in Florida. ASA, CSSA, SSSA International Annual Meeting, Salt Lake City, UT. https://scisoc.confex.com/scisoc/2021am/meetingapp.cgi/Paper/138891. [Abstract].   Garcia Calvo, B., E. Haramoto, M. Allen, S.K. Carter, P. Aryal, and C.A. Chase. 2021. Cowpea as a summer cover crop: Effect of germplasm and seeding rate on weed biomass. Proceedings of the 76th North Central Weed Science Society, p.74. http://ncwss.org/wp-content/uploads/2021-FINAL-NCWSS-Proceedings.pdf. [Abstract].   Aryal, P. and C.A. Chase. 2022. Rye cover crop termination timing effects on weed suppression in no-till corn. Proceedings of the Southern Weed Science Society, Volume 74. [Abstract]   Aryal, P. and C.A. Chase. 2022. Rye cover crop termination timing effects on weed suppression in no-till corn. Florida Weed Science Society meeting, Waimauma, FL. [Abstract]   Govindasamy, P., R. Liu, T. Provin, N. Rajan, F. Hons, J. Mowrer, and M. Bagavathiannan 2021. Soil carbon improvement under long‐term (36 years) no‐till sorghum production in a sub‐tropical environment. Soil Use and Management, 37(1), 37-48.   Haddad, S.A., J. Mowrer, and B. Thapa. 2022. Biochar and compost from cotton residues inconsistently affect water use efficiency, nodulation, and growth of legumes under arid conditions. Journal of Environmental Management, 307, 114558.   Mowrer, J., Dembele, G., Strzelec, A., and Thapa, B. 2022. Amending Soil with Biochar from Available Agricultural Wastes to Improve Sustainability of Cotton Production in Mali. Agrosystems, Geosciences, and Ecosystems.  https://acsess.onlinelibrary.&zwnj;wiley.com/doi/10.1002/agg2.20298.   Ouattara, A., B. Koulibaly, D. Dakouo, P. Bazongo, K. Coulibaly, J. Mowrer, and B.H. Nacro.  Effects of three cropping management systems on crop yield and soil chemical characteristics of tropical ferruginous soil in West of Burkina Faso (accepted African Journal of Agricultural Research (AJAR) 083121).

Impact Statements

Our participants are contributing the development of a cover crop selector tool and to developing and refining region-specific cover crop recommendations. Teams of experts from the Southern region are established to review information and data verification. After data verification, it should take approximately 2 months to bring to the program live.

Date of Annual Report: 10/23/2023

Report Information

Annual Meeting Dates: 02/13/2023 - 02/15/2023
Period the Report Covers: 07/01/2022 - 06/30/2023

Participants

Basinger, Nicholas (nicholas.basinger@uga.edu) – University of Georgia
Chase, Carlene (cachase@ufl.edu) – University of Florida
Fultz, Lisa (lfultz@agcenter.lsu.edu) – Louisiana State University
Gamble, Audrey (avg0001@auburn.edu) – Auburn University
Haramoto, Erin (erin.haramoto@uky.edu) – University of Kentucky
Howe, Julie (julie.howe@ag.tamu.edu)- Texas A&M University
Knappenberger, Thorsten (knappi@auburn.edu) - Auburn University
Maity, Aniruddha (azm0343@auburn.edu) - Auburn University
Maltais-Landry, Gabriel (maltaislandryg@ufl.edu) – University of Florida
Mowrer, Jake (jake.mowrer@tamu.edu) – Texas AgriLife Research (recorded report)
Mulvaney, Mike (mjm1166@msstate.edu>) - Mississippi State University
Narayanan, Sruthi (skutty@clemson.edu) - Clemson University
Rajan, Nithya (nrajan@tamu.edu) – Texas AgriLife Research
Ruiz-Menjivar, Jorge (jorgerm@ufl.edu) – University of Florida (Zoom)
Swisher, Mickie (mesw@ufl.edu) – University of Florida
Sykes, Virginia (vsykes@utk.edu) – University of Tennessee
Temu, Vitalis (vtemu@vsu.edu) – Virginia State University
Zhang, Xi (xizhang@agcenter.lsu.edu) - Louisiana State University

Brief Summary of Minutes

The meeting was held virtually on August 21, 2023 after the summer board meeting of the Southern Cover Crop Council (SCCC). The meeting started with an introduction of all project participants. Dr. Nithya Rajan moderated the meeting. The discussions started with remarks from the NIFA representatives, Dr. Mathieu Ngouajio and Dr. Bisoondat Macoon. This was followed by objective report presentations.

Dr. Jake Mowrer presented the report for Objective 1 [Identify a common set of biological and economic measures that can be applied across crop and cover crop combinations throughout the region to generate a region-wide database]. The Objective 1 team is looking at various soil health indicators and economic indicators of soil health. Activities to date include 1) forming the authorship team for the review paper that now has a full outline and a preliminary draft & 2) sources of funding for soil health research identified. Planned activities include pushing review manuscript forward and holding meetings for grant writing.

Dr. Audrey Gamble presented the report for Objective 2 [Select and evaluate summer and winter cover crop germplasm for regional adaptability and determine the appropriate timing of planting, seeding rates, utilization of cover crop goods (includes grazing), and termination to optimize benefits without adversely affecting cash crop cycles]. Dr. Gamble presented results from a legume species and seeding trial that was conducted in 2019-2020 and 2021-2022 with 10 states. Data analysis is ongoing. The team plans to submit a publication by January 2024. Key preliminary results include finding no systematic benefit of increasing the seeding rate of legumes (like previous small grain trials). Dr. Gamble also presented results from 2022-2023 cover crop variety trial.

Dr. Nithya Rajan presented the report for Objective 3 [Assess the influence of cover crops on soil moisture, nutrient cycling, and soil microbiology]. All members have ongoing experiments looking at various aspects of this objective, however, Dr. Rajan discussed the need to pursue grant funding to develop a common project including participants. Some of the research ideas that were proposed at the 2022 annual meeting are currently being researched by Dr. Rajan in cotton and Dr. Mulvaney in soybean. The team is planning to continue their efforts for grant proposal submissions and leveraging activities.

Dr. Carlene Chase presented the report for Objective 4 [Characterize cover crop efficacy for enhancing cropping system resilience to weeds, pests, and plant pathogens]. An update was provided for two studies. The first experiment includes 3 different cowpea lines x 5 seeding rates x 3 termination timing. The second experiment, funded by USDA_NIFA, aimed at finding delaying rye termination on biomass, weed suppression, and subsequent corn yield.

Dr. Mickie Swisher presented objective 5 report [Generate an economic database that researchers, technical advisors, and farmers can use to assess the short and long-term economic outcomes of cover crop use]. A review on the environmental impacts of cover crops was published. A manuscript is in preparation on factors that affect farmers’ adoption and intensity of cover cropping using the theory of planned behavior. This focuses on farmer perception towards climate change, sources of information and how they are perceived, demographic variables, farm characteristics, and how they interact to affect the adoption of cover crops. Feedback from think tanks and advisory councils from very experienced cover crop users include the following: 1) longer experiments are needed, especially for soil health; 2) larger scale is key as within-field variability can be large; and 3), not enough emphasis on profitability, too much on maximum yield. Several moved from very diverse mixtures to 3-4 species mixtures.

The meeting was wrapped up in the afternoon with a discussion about grant proposal writing. The meeting was adjourned at 2.30 PM.

Accomplishments

Objective 1: Soil health-specific funding has been sought as an objective team this year.  This includes solicitations from the Specialty Crop Research Initiative, Foundational and Applied Science Program, Conservation Innovation Grants, Sustainable Agricultural Systems, and others.  The objective team has not yet been awarded funding based on proposals. However, members of the objective team have been successful in securing awards.  Current efforts of the objective team include submitting proposals to the USDA-NIFA OREI and SAS programs for the FY 2024 cycle. Objective 2: Collaborators in ten states participated in a multi-state trial to evaluate winter legume cover crop species and seeding rates from 2019-2022. Overall, results from this trial illustrate the variation both among species and among varieties within species as well as highlight top-performing varieties for the Southern region. While these results draw from a wide range of environmental conditions representative of the Southern US, the cold-snap in December 2022 was unusual for this region. Results from brassica varieties and some more cold-sensitive clover varieties may not be representative of a more typical winter. Cereal rye, hairy vetch, and crimson clover varieties were among the top-performers for the 2022-2023 season. Although top-performing varieties of cereal rye and hairy vetch were generally the same across locations and termination timings, crimson clover varieties exhibited greater variation by location. Selecting a mix of top-performing varieties that offer complementary benefits, such as early season cover, biomass at termination, and nitrogen release after termination, can help maximum the benefits of cover crops to a succeeding cash crop system. Objective 3: The team continued to leverage ongoing research for this objective. There are a number of ongoing experiments in participating states where cover crops are being evaluated for its impact on soil moisture, nutrient cycling, and soil microbiology. Depending on the location and the type of cover crop used, varying responses were found. The team has several graduate students working on the projects related to Objective 3.  Team members are also actively seeking external grants to address goals related to Objective 3. Objective 4: Common Experiment 2 funded by USDA NIFA Sustainable Agricultural Systems Coordinated Agricultural Project award no. 2019-68012-29818 is in its third and final year of field research. The multistate study is focused on the effects of planting no-till corn into a rye cover crop (planting green) on weeds, insect pests, slugs, and pathogens. Although terminating rye after planting results in the higher cover crop biomass than termination 1-3 weeks before planting there was no difference in weed biomass at termination or at the V4-V5 stage of a subsequent corn crop. Compared to a no cover crop control all rye termination timings effectively suppressed weeds in the corn crop. However, post-planting rye termination resulted in a corn yield penalty compared with the control and the preplant termination timings. For a second multistate study aimed at developing seeding rate and termination timing recommendations for cowpea germplasm lines US-1136, US-1137, and US-1138 data analysis has been completed and a manuscript has been prepared that will be submitted for publication in 2024.  Objective 5: The team accomplishments in the current reporting period provide summative components in the research conducted over the life of this project. This work was itself built on previous research conducted by researchers who remain deeply involved in this final year of research under our current Hatch project. One team of social science researchers (Liu, Ruiz-Menjivar, Hu, Zavala and Swisher) completed a scientometric review of the existing literature about the environmental impacts of using cover crops (Knowledge Mapping of the Extant Literature on the Environmental Impacts of Using Cover Crops – A Scientometric Study, Environments 2022, 9(9), 120; https://doi.org/10.3390/environments9090120). This contribution to the literature will be used in the development of our on-going cover crop research. We conducted the final think tank meeting of experienced growers. This final discussion combined with our previous think tank meetings with cover crops users who have years of experience with cover crops combined with our field assessments of cover crop research plots each year provided us with three major conclusions based on farmers’ perspectives on the use of cover crops and provide the basis for future research.  (1) New adopters need to commit to a lengthy trial of cover crops on their farms to adequately assess both the biological and economic advantages of using cover crops. (2) Larger scale trials are needed to make direct comparisons between a farmer’s current practices to explore the full range of variance under field conditions. (3) Future research needs to focus on profitability, not maximum yield.  Farmers consistently find that the cost of materials and labor needed to maximize yield can reduce overall profitability.

Publications

Boakye, D.A., P. Aryal, C. A. Chase, M.V. Bagavathiannan, A. Basche, H. Darby, M. L. Flessner, E. Haramoto, R.G. Leon, S.B. Mirsky, A. Robertson, M. Ruark, M.R. Ryan, N.J. Seiter, K. Tilmon, P. Tomlinson, J.F. Tooker, M. VanGessel, J.M. Wallace, J. Adam, T. Ferreira de Almeida, A. Decker, K. Loria, R. Matthiessen-Anderson, J.M. McVane, F.H. Oreja, D. Presley, A. Raudenbush, L. Ruhl, C. Sias, B. Scott, E. Sweep, and A. Waggoner et al. 2023. Effects of delaying rye cover crop termination on cover crop biomass, weed suppression, and corn yield. Proceedings of the Weed Science Society of America. https://wssa.net/wp-content/uploads/WSSA-WSWS-2023-Proceedings.html. Boakye, D.A., C.A. Chase, D. Presley, S. Mirsky, A. Robertson, E. Haramoto, J. Tooker, R. Matthiesen-Anderson, A. Basche, M. Bagavathiannan, J.M. McVane, K. Loria, N. Seiter, J. Adam, J. Wavering, C. Sias, A. Waggoner, P. Tomlinson, M. Flessner, T. Ferreira de Almeida, J. Miller, M. VanGessel, H. Darby, M. Ryan, K. Tilmon, A. Raudenbush, V. Singh, M. Ruark, R. Leon, and L. Ruhl. 2023. Impact of rye cover crop termination timing on cover crop biomass, weed suppression and corn yield. American Society for Horticultural Science Annual Conference. <a href="https://ashs.confex.com/ashs/2023/meetingapp.cgi/Paper/40039">https://ashs.confex.com/ashs/2023/meetingapp.cgi/Paper/40039</a>. Chase, C.A., D.A. Boakye, P. Aryal, N.T. Basinger, L. Fultz, A.V. Gamble, E. Haramoto, N. Rajan, V. Temu, and E. Valencia. 2023. Multistate assessment of cowpea cover crop germplasm, seeding rate, and termination timing effects on weed suppression. Proceedings of the Weed Science Society of America. <a href="https://wssa.net/wp-content/uploads/WSSA-WSWS-2023-Proceedings.html">https://wssa.net/wp-content/uploads/WSSA-WSWS-2023-Proceedings.html</a>. Liu, Y., Ruiz-Menjivar, J., Hu, Y., Zavala, M., & Swisher, M. E. (2022). Knowledge Mapping of the Extant Literature on the Environmental Impacts of Using Cover Crops—A Scientometric Study. Environments, 9(9), 120.

Impact Statements

Our project assembled a diverse team of scientists from the southern states of the United States to collaborate on a common goal: developing cover crop management strategies to benefit cropping systems. Our collaboration has resulted in multi-state trials of cover crops, yielding valuable information that can assist farmers in selecting suitable cover crop varieties for their respective regions.