Improving Silvopasture Systems in the South: Identification of Suitable Forage Crops and Enhancement of Environmental Quality in Upland Forests

Final report for LS16-273

Project Type: Research and Education
Funds awarded in 2016: $135,487.00
Projected End Date: 09/30/2019
Grant Recipient: Furman University
Region: Southern
State: South Carolina
Principal Investigator:
Dr. John Quinn
Furman University
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Project Information


Growth in the human population and more meat intensive diets are increasing the demands on farming and food systems. At the same time, rapid urbanization threatens the existence and economic viability of farmland, particularly in the southeastern United States. Thus, data are needed that increase the economic stability of farmers while enhancing environmental quality within the farm and in the larger landscape. Agroforestry systems, more specifically silvopasture systems, integrate working trees with animal production, providing multiple environmental and economic benefits to a farm and the broader ecosystem, but are not widely used in agriculture. One barrier to adoption and research in agroforestry systems is the time required to grow mature stands of trees. Data highlighting the success of systems can be used to inform the broader farming community about successful farming methods for the South. Thus, the primary purpose of this project is to improve the economic and environmental sustainability of grazing efforts in agroforestry systems embedded in farmland by restoring forest patches invaded by exotic plants and developing sustainable grazing practices. We will do this by 1) identifying suitable animal forage mixtures, 2) acquiring baseline data on soil fertility to track responses to agroforestry methods, and 3) testing if the above restoration efforts improve wildlife habitat in upland forests in agroecosystems. Identification of shade-tolerant forage crops and improvement of soil quality can reduce the post-grazing recovery times within and between years. The reduced recovery time will increase the economic value of these forest patches to the producer. Removal of invasive species in these forests will improve nesting and foraging habitat for game and non-game wildlife. We will work closely with four farms in the Carolinas and Georgia. We will restore upland forest patches at each site, and then plant replicated mixtures of different forage crops in the restored forests. All plots will be grazed as part of the restoration efforts, improving the economic productivity of each farm.  We will evaluate, pre-grazing, performance of the forage species under shade by measuring plant biomass, C to N ratio, stand density, and percent cover. We will measure bird richness and abundance in restored and control plots. We will collect preliminary data on soil organic carbon on soil organic nitrogen as a measure of soil fertility for future pre-post comparisons.  Managed forage and grazing should reduce the recovery time required between grazing periods, increase producer resiliency to variations in temperature and precipitation, increase resilience to fluctuations in economic markets, improve habitat quality for local wildlife, and increase soil quality. Last, and perhaps most importantly, we will magnify the education benefits of the project by working closely as researchers and practitioners and by sharing results and lessons learned through multiple education outputs and formats. We will share lessons learned and results via on-farm tours, outreach publications, and video. Throughout the study, we will evaluate the effectiveness of our research, engagement, and information dissemination components using a mixed-method assessment.

Project Objectives:

In this project, we addressed the articulated need of cooperating farmers for applied data on forage production and forest restoration by using existing forest stands at four farms across three states (SC, NC, GA) in the southern Piedmont, to test the performance of different forage combinations and the resulting environmental and social change. The specific five objectives of this project were: 

Objective 1) Identify crop mixes that best grow under the shaded conditions of restored upland agroforestry systems

Objective 2) Measure the response of wildlife communities to forest restoration and ground cover planting

Objective 3) Collect preliminary data and research capacity to study how understory forage crops can be used to restore ecological function and services, in particular, soil fertility and health as measured by soil organic carbon and nitrogen content and stratification

Objective 4) Share results of the research through on-farm visits, publications, and an online video highlighting the lessons learned and management recommendations

Objective 5) Measure the knowledge, attitude, and information flows of pastured pork producers in the southeast


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Materials and methods:

The research was conducted on farms in the Piedmont ecoregion of  South Carolina, North Carolina, and Georgia. Key study sites were Greenbrier Farm in Pickens County, SC, Bio-Way Farm in Laurens County, SC, Spirit Creek Farm in Augusta-Richmond County, GA, and Spirit Level Farm in Rutherford County, NC. Other forested sites in Upstate South Carolina were included in the last two years to add replications.

Objective 1: We planted forage mixes of chicory, rye, alfalfa, and crabgrass and an off the shelf control in multiple (an average of 6 per site) forest understory plots at each of the four sites. To augment the value of the on-farm field plots, greenhouse trials of single species and species mixes were conducted at Furman University. 

Objective 2: We conducted active and passive sampling of avian communities in paired silvopasture and unmanaged forest patches. 

Objective 3: We analyzed SOC and SON concentration, stratification, and C:N as a measure of soil quality in forest soils. Soil cores and profiles were collected and analyzed from 36 locations during or prior to grazing in forested patches on all four key farms.

Objective 4: We attended and presented at local and regional sustainable agriculture meetings. We developed digital media to share.

Objective 5: We reviewed farmer databases and websites to create a list of current pork producers. Pork producers were contacted and asked to complete a survey allowing for subsequent social network analysis (SNA) The survey was also administered in-person to a sample of pork producers at Upstate farmers markets in the fall of 2017. These data were analyzed in NODE XL for the creation of the community’s network map and metrics. We also followed this survey with a series of in-person interviews to add qualitative depth to the survey (particularly given the low levels of connectivity).

Research results and discussion:

Objective 1: In 2016 (the first growing season)), the Southeast experienced unusually dry and hot conditions with nearly 40% of the region classified in moderate-to-exceptional drought conditions. Thus, germination was very limited across the farms. During the subsequent fall, we did find that ryegrass spread late in the season did the best of the crops in the shade conditions of the project, providing sufficient ground cover for forage and soil retention. There were scattered volunteers throughout. In 2017 & 2018 there was no statistical difference between the forage mixes planted at the on-farm plots. Furthermore, surprisingly, neither forage mix maintained growth through the latter stages of growth. We did observe some volunteers later in the growing season, but not sufficient for forage or soil retention. One farmer did note that the understory plantings increased forage opportunities on the farm and improved the production system as a whole. 

To better understand dynamics observed in the field we conducted a series of greenhouse experiments where plants were grown in small pots (1 liter) under controlled temperature and humidity levels, but with limited sunlight (all plants were grown under shade-cloth). In our trial first iteration, we found that the diverse forage mixes (richness = 4), despite ecological theory, were lower in growth compared to single and double species mixes.  The next year we had a larger trial, with greater replication. In this iteration of the greenhouse trials, we found the opposite of the first year. Specifically, biomass was greater in more species-rich plots.  Differences were significant across all pairs except between one and two species and three and four species trials. Thus, these data suggest, though further research is needed, that three species mixtures may be a suitable starting point for future field trials in shade conditions. 

Objective 2 We found evidence of differences in avian communities between the two forest management treatments (improved and unimproved understory). Though species richness did not differ (alpha diversity ~15 for each treatment at each site), we did find that species overlap was only around 60%. These differences were likely due to 1) changing understory forest structure, in particular, opening up greater foraging opportunities in the understory for ariel insectivores (e.g., eastern kingbird), 2) the disturbance of the soil by the pigs, also increasing foraging opportunities on the ground, and 3) the loss of shrub cover (though primarily invasive plants) resulted in the loss of some shrubland birds. We did find that four bird species of South Carolina conservation concern were present on the silvopasture sites but not the controls. It should be noted, however, that the small sample size limits broader inference without future data. However, they do suggest future opportunities for collaboration between farmers and conservation biologists on forest restoration and wildlife management. 

Objective 3: Results from the soil cores indicated the greatest variation in soil organic matter in the upper 10 cm with SOC and SON concentrations that decreased exponentially with depth. SOC stock for the upper 10 cm averaged 32.1±8.6 Mg C/ha for grazed and 28.9±5.8 Mg C/ha for the ungrazed forest, similar to other findings for Piedmont forest soils. These results are slightly higher, but not significantly different than rotationally grazed pastures at Greenbrier Farms based on samples collected in 2016 and 2017 (26.6±6.20 Mg C/ha). SON stock for the upper 10 cm averaged 1.6±0.5 Mg N/ha for grazed and 1.7±0.5 Mg N/ha for ungrazed forest soils. These results are slightly lower, but not significantly different, than samples collected from Greenbrier Farms (2.0±0.6 Mg N/ha). The stratification ratio (0-10/20-30 cm) for grazed was 3.2±1.0 and for ungrazed was 3.4±1.7 forest. C:N ratios were slightly lower compared to other findings for Piedmont forest soils. High variability and lack of statistically significant difference for soil quality parameters between grazed and ungrazed forest patches may indicate that grazing in Piedmont forest could maintain or improve soil quality if immediately replanted with forage crops to reduce erosion. The results also suggest that forest soils, like the pastures, are still recovering from degradation caused by more than a century of intensive tillage cultivation.  Removal of invasive plants, such as privet, and increased rotational grazing combined with cover crops will likely improve soil quality as measured by carbon and nitrogen content.

Objective 4: Outreach was effective, though the absence of a clear "best" forage mixture limited the potential for simple information transfer and subsequent adoption. We have shared via on-farm sessions and farm meetings some of the challenges of on-farm research and assessment of sustainability via multiple criteria. We presented the work to farmers at local and regional meetings farmer-centered sustainable agriculture meetings. Our video on YouTube ( has over 200 views.

Objective 5: 30 farmers responded to the survey. 65% reported that they are full-time pork producers, meaning that they have no off-farm work. 75% own the land they farm, with an average farm size of 35 acres. The data illustrate low levels of social and professional networks within niche pork producers of the Piedmont region. Most farmers had one or two connections in which they interact with regarding their pork production. However, some farmers had no connections at all while others served as “hubs” for others and had multiple connections that spread out to connect with other internal networks. Nine farms had a degree (degree is a social network measure that counts all the ties directly linked to an actor) of 2 or higher. In-degree (a measure the number of ties received by a farmer from another farmer) ranged from 0 to 2.  Betweenness (a measure of the middle farmer or the farmer which is acting as a bridge to other) ranged from 0 to 28 with the majority of farmers have a score of 0. Despite the low connectivity, the most common information source was fellow farmers at 29.87%, and the least common being non-profit organizations at 6.5%. The majority of farmers sold directly to consumers via farmers market, CSA, or on-farm at 46% and retail at 22%. 

When interviewing participating farmers, three key challenges emerged 1) Managing the growing pains of becoming a mid-sized producer while continuing to provide the ecosystem services expected by existing customers (such as aesthetics, a direct relationship with the farmer, and direct single-farm to table products) while scaling-up for requirements of wholesalers and larger stores; 2) the desire to provide a living wage and benefits such as health insurance to employees while maintaining a profitable business and 3) the difficulty that newcomers to a market create for established producers.  It was found that most farmers did talk to at least one other farmer about their pork production, though not always with another pork producer.  In addition, few smaller-scale producers had a partnership with a non-profit or extension agent, which made many feel they were “going it alone.”  Small and mid-sized pork producers also experience challenges when newcomers enter the direct-sale market, despite wanting to promote the well-being of small producers as a whole.  For example, when a new pork producer enters the market, they often set prices well below the market rate.  Those that have established a stable business often have to compete in the short term with these new prices while working to maintain their customer base.  Established farmers have seen newcomers not be able to sustain their low prices and quit, while the legacy of their “haphazard” prices remains.


Participation Summary
40 Farmers participating in research


Educational approach:

With the collaborating farmers, we have started to translate our collaborative research for a broad audience. John and Roddy shared their process at the CFSA meeting in a session on on-farm research. John shared the work at the CULTIVTE meeting hosted by the Greenville Tech Sustainable Agriculture Program and as a case study at EcoFarm. Results were shared by students at larger conferences including the Ecological Society of America, Association of Southeastern Biologists, and Association of American Geographers. 

All applicable findings will continue to be shared with extension educators in all three states, local farming organizations (e.g., CFSA), and local wildlife conservation organizations (e.g., Audubon Society). We have integrated processes and results in classroom instruction, including the Agroecology class offered by John Quinn at Furman University and other classes in the Biology and Earth and Environmental Science departments. We will continue to reach out to the Greenville Tech Sustainable Agriculture Program and make our data available to teachers for use in classes. 

Educational & Outreach Activities

5 Consultations
6 Curricula, factsheets or educational tools
2 On-farm demonstrations
1 Online trainings
1 Published press articles, newsletters
7 Webinars / talks / presentations
1 Other educational activities:

Participation Summary:

8 Farmers participated

Learning Outcomes

3 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key changes:
  • on-farm research

  • silvopasture practices

  • information exchange

Project Outcomes

4 Farmers changed or adopted a practice
2 Grants received that built upon this project
1 New working collaboration
Project outcomes:

This project has affected current agricultural sustainability by 1) providing a evidence of a lack of a social network to support pastured pork production in the southeast, 2) helping farmers understand the economic costs and benefits of silvopasture management, 3) collecting evidence of the wildlife benefits that silvopasture can provide, and 4)  building the foundations for collaborative research between farmers and natural and social scientists. This project will contribute to future sustainability via 1) new baseline data on soil organic carbon developed via silvopasture,  2) preliminary data from greenhouse trials on the relationship between diversity and biomass in shade conditions, 3) continued transfer of information between farmers on the logistics of restoring forest understory with swine, and 4) novel insights and emergent theories for future research at the intersection of economic, environmental, and social aspects of agroforestry in temperate agroecoregions. 


Based on this project we would recommend projects that;

  1. Address how farmers exchange information. Based on our follow up interviews we would hypothesize that a subset of books or websites could be the nodes of information exchange. We found it interesting that most producers we talked to saw these resources as more valuable. It would be then interesting to followup on how extension and farming organizations could leverage this shared literature as a means for information exchange
  2. Our project iterated between on-farm trials and greenhouse trials. The on-farm trials provided more useable data for the farmers but were harder to generalize as "academic" output. In contrast, the greenhouse trials provided statistically different patterns, but the farmers saw less value in them. Clearly both have value but to different audiences. Thus we would encourage SARE to continue to support iterative research that addresses both on-farm research questions and academic outputs. 
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.