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

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 (https://www.youtube.com/watch?v=XFDJ0F1U7h8) 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.