Date of Graduation
12-2022
Document Type
Thesis
Degree Name
Master of Science in Crop, Soil & Environmental Sciences (MS)
Degree Level
Graduate
Department
Crop, Soil & Environmental Sciences
Advisor/Mentor
Savin, Mary C.
Committee Member
Philipp, Dirk
Second Committee Member
Miller, David M.
Third Committee Member
Ashworth, Amanda J.
Fourth Committee Member
Bertucci, Matthew B.
Keywords
Glomalin; Silvopasture; Soil Quality
Abstract
Silvopasture practices incorporate forages and woody perennials in the same system in order to create a sustainable system. The main objective of this study was to determine if one of two forage species can be successfully established in order to investigate agroforestry as a management system to promote soil health. Within a bottomland mixed hardwood forest in the Arkansas River Valley, an agroforestry system was established to evaluate three basal areas (determined as the cross-sectional area of trees at breast height) (7, 11.5, and 16 m2/ha) with mounded areas and two forages, tall fescue (Lolium arundinaceum [Schreb.] Darbysh) and orchardgrass (Dactylis glomerata L.) compared to a mulched control (no forage) in each basal area. Soil samples were collected at the 0-10 and 10-30 cm depths in the fall (November 2021) and late spring/early summer (June 2022) to assess soil health properties [easily-extractable glomalin-related soil protein (EE-GRSP), Mehlich-III extractable nutrients, total and particulate organic matter (TOM and POM, respectively), total carbon and nitrogen, aggregate stability, bulk density, particle size, pH and electrical conductivity] a year and year and a half after treatment establishment. Additionally, forage dry matter production was assessed via aboveground biomass collected in June 2021, October 2021, and June 2022. Belowground biomass was assessed through utilization of ingrowth root cores to capture fine root production (>2mm) over a period of 15-months. Photosynthetic active radiation (PAR) and leaf area index (LAI) were assessed to determine basal area influence upon understory light inputs. An increase in P, K, Mg and Zn was observed in the 11.5 m2/ha basal area in comparison to the 7 and 16 m2/ha treatments at the June 2022 sampling. The EE-GRSP in October 2021 at the 10-30 cm depth differed between the 7 and 16 m2/ha basal treatments with a mean of 0.73 (± 0.05) and 0.95 (± 0.05) g/kg respectively. The EE-GRSP was significantly correlated with TOM, P, K, Ca, Zn and B for both sampling dates. Forage yield varied on a seasonal scale in which basal area affected biomass in June 2021 and 2022, while aboveground biomass was greater at high mound compared to low mound elevation position in October 2021. Forage aboveground biomass collected in June 2022 was 204.8 (± 17.2) and 271 (± 17.6) g/m2 for fescue and orchardgrass, respectively, which were different. Belowground fine root productivity resulted in biomass of 235.29 (± 47.06), 500 (± 141.18) and 94.12 (± 82.35) g/m3 for fescue, orchardgrass, and the mulch control, respectively. Orchardgrass established with greater biomass than tall fescue; however, soil properties demonstrated few changes from forage vegetation within the first two years of establishment. Glomalin-related soil protein (GRSP), a glycoprotein often related to carbon and nitrogen, soil aggregation, and arbuscular mycorrhizae, indicated the potential to reveal changes at the soil depth of 10-30 cm. Continued evaluation of EE-GRSP would reveal whether forage production and basal area management following establishment of agroforestry practices improved soil functional properties related to promotion of soil structure and the sequestration of nutrients.
Citation
Janorschke, M. (2022). Short-Term Changes within an Agroforestry System Managed at Three Basal Areas with Fescue Compared to Orchardgrass. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/4709
