Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references.

Silvopasture is a land-use management practice which intentionally integrates trees, forage, and livestock. It is increasingly prevalent in outreach and extension, yet considerations for adoption are complex. The implementation of a cost-share initiative for silvopasture created by the Natural Resource Conservation Service (NRCS) in Virginia in 2011 provides an opportunity for landowners to establish silvopasture systems on their properties, thus diversifying land management and income, as well as providing environmental benefits. However, research on who might adopt silvopasture and why is needed. For this research, a mail survey was distributed to 307 cost-share enrollees in NRCS' livestock limitation initiatives and 139 were returned (45.3%). The first objective of this survey was to gauge interest in two forms of silvopasture implementation: a) thinning a woodlot and b) planting trees in a pasture. Furthermore, the study was utilized to test which hypothetical benefits might increase a livestock producers' interest in either implementation form. Results show that respondents preferred thinning to planting but risk and uncertainty were perceived in both. Environmental outputs and assistance from technicians increased interest in both practices over economic benefits; however, livestock performance was most important. Literature on the topic aligns with findings and highlights that more research is needed to understand risk, environmental, and resource-related factors. The second objective was to measure interest in silvopasture and classify respondents based on their operational or their beliefs-based characteristics and assess which classification set mattered more. Results indicated that interest in silvopasture varied but the majority (60%) indicated they were either interested or very interested. Two-step cluster analysis was used to classify respondents based on their operational considerations and a combination of Exploratory Factor Analysis and K-means clustering was used to group livestock producers according to their beliefs on traditional and land-use values. A Kruskal-Wallis independent samples analysis for each classification revealed no statistically significant differences in the interest in silvopasture between operational groupings. Conversely, there were statistically significant differences in silvopasture interest according to beliefs-based classifications. These results suggest that operations of livestock producers do not matter as much as their attitudes and beliefs related to the practice. A cross-tabulation of the operational classification and beliefs cluster resulted in no correlation. Literature suggest both operational characteristics and producer beliefs may matter in agroforestry adoption, but that positive or negative correlation in terms of interest may vary. / Master of Science / Silvopasture is a agroforestry conservation practice that integrates trees, forage, and livestock in a managed system. The adoption of this practice is complex, though education on the practice has been increasing. A cost-share initiative for silvopasture was created by the Natural Resource Conservation Service (NRCS) in Virginia in 2011, which creates the opportunity to implement silvopasture systems on landowner properties. This system could lead to more diversification of land and income, as well as providing environmental benefits. However, more research is needed. A mail survey was sent to 307 NRCS cost-share enrollees who were managing livestock and 139 were returned. The survey had two objectives; the first was to measure interest in the two forms of silvopasture implementation: a) thinning a woodlot and b) planting trees in a pasture. Hypothetical benefits which might increase a livestock producers’ interest in thinning or planting for silvopasture was also measured. Results show that respondents had a preference for thinning over planting. Economic benefits were not as effective in increasing interest compared to environmental outputs and assistance from technicians; however, livestock performance was most important. Findings were aligned with literature on silvopasture and agroforestry but more research is needed. The second objective was to measure interest in silvopasture and classify respondents based on their operational or their beliefs-based characteristics and to see which classification set mattered more. Results indicated that interest in silvopasture varied but the majority (60%) indicated some level of interest. Statistical analyses were used to classify respondents based on their operational considerations and used to group livestock producers according to their beliefs on traditional and land-use values. Outputs showed no statistically significant differences between operational groupings and their interest in silvopasture. There was a statistically significant difference in silvopasture interest according to beliefs-based classifications. These results indicate that the operations of livestock producers do not matter as much as their attitudes and beliefs on the practice. Previous literature indicates that both operational characteristics and producer beliefs may matter in agroforestry adoption, but interest may vary regardless.

Biochar is a form of stable organic carbon whose application to soils has the potential to sequester large amounts of atmospheric CO2 while improving the physical, chemical and biological properties of soil. However, the optimal rates and methods of biochar application are unknown for many situations. Three experiments were performed to test methods of biochar application to soils as a stand-alone amendment, in combination with biosolids as a complementary amendment and in-situ through controlled landscape burning. The first was a greenhouse pot study, which involved combining biochar with spoil from an Appalachian surface coal mine to grow trees. Biochar combined with mine soil produced a much higher growth rate for trees, and pure biochar helped tree root growth, suggesting that it might be useful as a broadcasted amendment, as a nursery growing medium or as a backfill in tree planting holes. The second experiment explored methods to combine biochar and biosolids materials to form a granular product. Combining biochar and biosolids before applications reduced windborne losses of biochar as well as the nutrient leachate produced by the biosolids. Drum rolling was found to work best for producing aggregate granules. Wetting pure biochar to 100% gravimetric water content before applications reduced windborne losses from over 50% to under 5% as compared to when it was applied as a dry product. A series of controlled burns were conducted in the third experiment to determine the ideal range of meteorological conditions to produce the highest possible biochar yields in-situ. Relative humidity, forest litter moisture and ambient temperature were found to be the governing factors over the tonnage of biochar produced. Up to 3.0 Mg Ha-1 of biochar were produced under ideal conditions by controlled burning. Repeated high-yielding burns have the potential accumulate large amounts of biochar in the soil to improve soil properties. / Ph. D.

Trees in silvopastures may provide forage-livestock systems with multiple goods and services, including shade, shelter, and browse. Reports of forage and animal productivity from these systems indicate that, in some cases, animal gains are similar or better despite lower forage yield. The relationship between grazing system, body temperature, grazing behavior, and animal performance was explored in this study. Black walnut and honeylocust-based silvopasture systems were compared with open pastures in a randomized complete block design (r = 3) over three summers. Pastures were rotationally stocked with 5-7 lambs depending on forage availability. Lambs were weighed every four weeks. Behavior measures were recorded within a replicate within a week, and these measures were taken sequentially within three experimental periods. Ewe lambs (n = 3) were equipped with a vaginal temperature sensor (3 days) and an audio recording device (1 day) to detect prehension events. Cameras documented lamb behavior every 60 seconds. Forage measurements taken with a rising plate meter indicated greater productivity in the honeylocust silvopasture (5020 ± 30 kg · ha⁻¹ ) compared to the open pasture (4930 ± 30 kg · ha⁻¹ ; P = 0.0281), though forage availability in the black walnut silvopastures (3560 ± 30 kg · ha⁻¹ ) was lower than within the other treatments (P < 0.0001). There was no difference in animal gains between systems (P ≥ 0.4813), though gains were highest in the honeylocust silvopastures (25.6 ± 3.4 kg · period⁻¹ ), followed by the gains of the black walnut silvopastures (22.3 ± 3.4 kg · period⁻¹ ), and the gains of the open pastures (22.2 ± 3.4 kg · period- 1 ). Lambs in silvopastures spent more time lying down than animals in the open pastures (P ≤ 0.01), while lambs in the open spent more than two hours longer each day standing (P < 0.0001). During the hottest part of the day, ewes in the open pasture were 0.4 °C hotter than ewes in the black walnut silvopastures (P ≤ 0.0202). Lambs in the black walnut silvopastures grazed more (488 ± 14 minutes · day⁻¹ ) than lambs in the honeylocust silvopastures (438 ± 15 minutes · day⁻¹ ; P = 0.0192) and the open pastures (417 ± 14 minutes · day⁻¹ ; P = 0.0009), with no difference between the latter two systems (P = 0.3073). There was no difference in daily bites taken (P ≥ 0.7222), though lambs in the silvopastures grazed more frequently than lambs in the open pastures. In one six week winter grazing study, animal performance in the honeylocust silvopastures was compared with the productivity of lambs grazing the open pastures and the black walnut silvopastures. The objective of this study was to determine the effect of these pods on lamb growth when animals grazed stockpiled tall fescue (Schedonorus arundinaceus). Preand post-graze forage mass was estimated with a double sampling technique using a rising plate meter. Treatment pastures were rotationally stocked with three (walnut) or six lambs per experimental unit depending on forage availability. Fescue grab samples were collected every other rotation. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and total digestible nutrients (TDN) were estimated with a robust equation using NIR spectroscopy. Pre- and post-graze pod mass per hectare was estimated using randomly placed quadrats. Lambs were naïve to pods and did not readily consume the fodder until four weeks into the trial, and the methods for estimating pod intake were not sufficient to detect pod differences in pre- and post-graze pod mass. Forage availability in the honeylocust silvopastures (5130 ± 90 kg · ha⁻¹ ) and open pastures (5050 ± 90 kg · ha⁻¹ ; P=0.7580) was greater (P < 0.0001) than forage availability in the black walnut silvopastures (3790 ± 90 kg · ha⁻¹ ). Treatment had no effect (P = 0.3763) on average daily gains across the six weeks of the study. However, lambs within the honeylocust silvopastures had greater (P = 0.0251) average daily gains in the final period (0.12 ± 0.02 kg · day⁻¹ ) than lambs within the open pastures (0 ± 0.02 kg · day⁻¹ ), and lambs were observed consuming the pods. These data suggest that honeylocust pods may support greater gains of lambs, but that previous exposure and longer study periods in pasture settings may be necessary to see their nutritional benefit when grazing high quality forages. / Ph. D.

Silvopastoral management has potential to diversify and increase the output from livestock production systems. Silvopasture production offers solutions to many management issues associated with grazing systems in the Appalachian region. Several tree species have been proposed for silvopastures in humid temperate regions, but little data comparing animal performance from systems with different deciduous tree species are available. Forage and animal performance was compared from open systems (i.e., no trees) with that from silvopastures containing 13-yr-old honeylocust (Gleditsia triacanthos) or black walnut (Juglans nigra) trees. Cool-season grass-legume pastures were rotationally stocked with hair sheep crosses from mid-June through September. The objective of this project was to determine carcass characteristics and meat quality of hair sheep crosses grazing honey locust or black walnut silvopastures in comparison with traditional pasture systems. Forage production varied by year with black walnut having lower production, especially in the 2009 season with black walnut producing less forage compared to open pastures and honeylocust silvopastures (P=0.0008). Only small differences in forage nutritive value were observed. Total gains and average daily gains (ADG) did not differ by treatment in 2008, but during the 2009 season black walnut silvopastures produced half the total gains (P=0.0427) and ADG (P=0.0513) of open pastures and honeylocust silvopastures. Carcass characteristics evaluated did not vary among treatments except hot carcass weight with black walnut having lower weights (P=.0045). Meat quality characteristics did not vary among treatments (P>0.1). Shear force and fat content showed great differences and varied by year (P<0.05). Overall, carcass and meat quality was similar for all treatments showing great promise for silvopastures. / Master of Science

Incorporating high-sugar varieties of honeylocust (Gleditsia triacanthos L.) or black walnut trees (Jugulans nigra L.) into pasture systems may improve soil and water quality, increase biodiversity, and diversify farm incomes. Studies of productivity and management are needed to understand the trees' potential. Research was conducted in the agroforestry demonstration plots at Virginia Tech's Kentland Farms to 1) estimate both the variability of seedpod yield and nutritive value from juvenile Millwood honeylocust trees, 2) measure changes in nutritive value and digestibility over-winter in Millwood and wild-type honeylocust seedpods, and 3) estimate black walnut biomass productivity, timber quality, nut production, and kernel quality in response to tree density and topography within an emulated silvopasture. Ground Millwood seedpods were comparable to whole-ear dent corn in terms of nutritive value. Both ground pods and seeds were highly digestible (78.7 and 96.3%, respectively) and low in fiber and lignin. Seeds, with over 20% crude protein (CP), have potential as a CP supplement. Millwood trees displayed alternate bearing patterns with 3-yr average yields of approximately 12 kg tree-1. Total aboveground biomass for black walnut trees planted on toe-slopes (109.0 kg) was 72% greater than at back slopes (63.2 kg) and nearly 3-fold more than at shoulder-slopes (37.6 kg). Nut yields ranged from 0 to 7.9 kg of dried, hulled nuts tree-1 year-1. All walnut trees displayed alternate nut bearing patterns and nut production was marked by high variability. / Master of Science

The goal of this research was to determine the interactions between forage and tree components of a silvopasture system. Two studies were performed on adjacent sites established in 1995 at Virginia Tech's Kentland Research Farm. The objectives of the studies were to: 1. Determine the influence of honey locust and black walnut silvopastures on indicators of soil quality when compared to open pasture. 2. Determine if silvopasture systems changed forage mass production and soil water compared to open pastures. The study on soil quality indicators was performed in a previously grazed silvopasture. Samples were collected from the upper 15 cm of soil at three distances from the tree rows. Total N (p= 0.0219), total C (p= 0.0216), extractable P (p= 0.063), extractable K (p= 0.0347) and microbial organic C (p= 0.0255) were greater in honey locust silvopastures. The highest concentration of soil nutrients and best soil physical and chemical properties were observed 1.5 m from the tree stem. Forage growth and soil water were measured in silvopastures in 2006 and 2007. In 2006 there was higher forage growth in the black walnut and honey locust than beneath 70% shade cloth. In 2007, with a 50% shade cloth, forage growth was similar in all treatments. Initial soil water content was highest under shade cloth in 2006. In 2007 the rate of soil drying was lowest beneath the shade cloth. The presence of trees did not negatively effect forage growth and silvopasture systems improved the soil quality indicators compared to open pasture. / Master of Science

Silvopasture is the intentional integration of trees with forages and livestock. In Blackstone, Virginia a silvopasture management plan was created in a thinned, timber stand seeded with a cool-season forage mixture. Treatment pastures for this study included an open pasture, a thinned pine silvopasture, a thinned hardwood silvopasture, and a cleared and replanted new pine silvopasture. Cattle were introduced in 2017 and rotationally stocked within each pasture according to forage availability. Objectives were to determine the forage availability, forage nutritive value, and the performance of heifers in silvopasture and open pasture systems. Additionally, the new pine silvopasture was grazed to determine the effect of cattle on tree seedlings without protection. Forage availability was affected by date and year and was significantly lower in 2018 (3560 kg ha-1) versus 2017 (5350 kg ha-1). Pre-grazing forage availability was lowest in the pine and hardwood silvopastures in both years (4500 kg ha-1) compared to the open pastures (4920 kg ha-1; p < 0.0001). Date significantly influenced nutritive value, but only had date by treatment interaction in the 2017 grass crude protein and neutral detergent fiber sample. In 2017, the new silvopasture (61% TDN) had greater total digestible nutrients as compared to the open pasture and thinned hardwood silvopasture (57% TDN; p = 0.0292); there was no significant difference (p=0.3733) in total digestible nutrients in 2018 between pastures (58% TDN). In 2017, average daily gains of the heifers were greatest in the silvopastures in June (p = 0.0346). In 2018, average daily gain was lowest among silvopastures later in the summer compared to open pastures and new silvopastures (pJuly = 0.0051; pAugust = 0.0008). Remote temperature loggers were used to collect vaginal temperatures of the heifers over eight days in 2018. Silvopasture heifers had an average core temperature of 39.4 °C from 2-5 PM while heifers in the open pastures had an average temperature of 40.0 °C. A drone with a thermal camera was used to collect external hide temperatures in the morning and afternoon. Heifers in the silvopastures had lower heat loads in the afternoon while animals without shade experienced a 65% greater temperature increase between morning and afternoon when compared to the shaded animals. Silvopastures provide an opportunity to improve the welfare of grazing livestock in the summer, while improving the overall productivity and efficiency of land. Tree seedlings that were planted into pasture to create a new silvopasture experienced a 16% mortality rate while over 75% of tree seedlings had less than 50% damage after two years and would continue to produce trees with future economic and shade value. Future research should focus on how to implement silvopasture as part of a holistic grazing and management plan while continuing to evaluate cattle, forage, and tree response to silvopastures over multiple years. / Master of Science / Silvopasture is the intentional integration of trees with forages and livestock. In Blackstone, Virginia a silvopasture management plan was created in a thinned, timber stand seeded with a cool-season forage mixture. Treatment pastures for this study included an open pasture, a thinned pine silvopasture, a thinned hardwood silvopasture, and a cleared and replanted new pine silvopasture. Cattle were introduced in 2017 and rotationally stocked within each pasture according to forage availability. Objectives were to determine the forage availability, forage nutritive value, and the performance of heifers in silvopasture and open pasture systems. Additionally, the new pine silvopasture was grazed to determine the effect of cattle on tree seedlings without protection. Forage availability was lowest in the pine and hardwood silvopastures in both years compared to the open pastures. Nutritive value of forages was most greatly influenced by time rather than tree presence. In 2017, average daily gains of the heifers were greatest in the silvopastures in June. In 2018, average daily gain was lowest among silvopastures later in the summer compared to open pastures and new silvopastures. Internal and external body temperatures of heifers during the afternoon decreased with increasing shade availability with the greatest internal body temperatures occurring in unshaded animals. Silvopastures provide an opportunity to improve the welfare of grazing livestock in the summer, while improving the overall productivity and efficiency of land. Tree seedlings experienced minimal damage by cattle and would continue to produce trees with future economic and shade value. Future research should focus on how to implement silvopasture as part of a holistic grazing and management plan while continuing to evaluate cattle, forage, and tree response to silvopastures over multiple years.

Silvopastures integrate trees, forages, and livestock. Tall fescue, the dominant forage in much of the U.S., harbors an endophyte that produces toxic ergot alkaloids. Diluting the sward with other forages can reduce ergot alkaloid concentrations, but it is unknown how shade impacts alkaloid production and productivity of different forage mixtures. This study tested the effects of increasing shade and mixture complexity on sward yield, botanical composition, nutritive characteristics and ergot alkaloid concentrations. Slatted shade structures created 30, 50, and 70% shade compared to full sun. Three forage mixtures were evaluated (SIMPLE = tall fescue and white clover; INTERMEDIATE = SIMPLE + orchardgrass and red clover; and COMPLEX = INTERMEDIATE + Kentucky bluegrass, birdsfoot trefoil, and alfalfa). Fifty and 70% shade reduced yield while red clover and orchardgrass dominated shaded swards. Birdsfoot trefoil, Kentucky bluegrass, and white clover did not perform well in any treatment. Nutritive value declined beneath shade in spring and fall. Sward ergot alkaloid concentration increased beneath shade in simple mixtures because of greater proportions of tall fescue. In the intermediate and complex mixtures, ergot alkaloids were diluted by other forage species and was not affected by shade. This illustrates the importance of incorporating multiple species into the sward. Low light levels may not have been sufficient to meet the forages' high energetic demands in the spring. Even though total forage production or nutritive value may be sacrificed during part of the year, this may be compensated for by diverse swards diluting ergot alkaloid concentrations. / Master of Science

Integrating trees into pasture may be an effective management tool to improve water, nutrient, and light allocation and increase total system productivity in Appalachia. We tested this hypothesis in a silvopasture near Blacksburg, VA. In 1995, black walnut and honey locust trees were planted within plots (r=3) of predominantly tall fescue pasture. Across a 12% slope, trees were planted to create treatments of low, medium, and high tree densities at shoulder, mid, and toe slope positions within plots of honey locust and black walnut. Sampling sites (n=54) under tree density and slope position combinations were harvested May to October at 35-d intervals in 2002 and 2003 for determination of yield and nutritive value characteristics. Soil surface temperature, forage canopy temperature, soil moisture, and photosynthetically active radiation were measured to determine forage responses to field treatments as functions of resource allocation. Tree density had the greatest effect on forage production and nutritive value. Across both years, yields were 16% greater (P=0.0006) at medium density (6130 kg/ha) compared to forage mass at low (5280 kg/ha)) and high density (4970 kg/ha, SE=130). Increasing tree density did not affect (P>0.2) ADF, CP, P, K, and Mg levels, but reduced (P<0.001) NDF and TNC, and increased (P<0.0001) ADL and Ca. Elevated soil surface and forage canopy temperatures limited forage production and nutritive value at low density, while low light levels were the limiting factor at high density. Moderating forage microclimate with appropriately spaced trees is an effective way to improve forage production in temperate pastures. / Master of Science