Impact of Biochar Application on Agricultural Landscapes Through Soil Infiltration and Changes in Soil Physical Properties
Open Access
- Author:
- Morris, Brian
- Graduate Program:
- Soil Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- September 20, 2024
- Committee Members:
- Tyler A Groh, Thesis Advisor/Co-Advisor
Jonathan M Duncan, Committee Member
Patrick Drohan, Professor in Charge/Director of Graduate Studies
Heather Elise Preisendanz, Committee Member - Keywords:
- biochar
concentrated flow paths
soil water infiltration
infiltration
TMDL
chesapeake bay
cornell sprinkle infiltrometer
bulk density
particle density
hydrophobicity
agricultural landscapes
riparian forest buffers
riparian buffers - Abstract:
- As the largest estuary in the United States, the Chesapeake Bay has a long history of industry and pollution. Algal blooms and eutrophication are common problems seen throughout the Bay. In 2010, The United States Environmental Protection Agency stepped in to assist shareholder states (Virgina, Maryland, Delaware, West Virgina, Pennsylvania, New York and the District of Columbia) to create a Total Maximum Daily Load (TMDL) for the entire watershed. The TMDL establishes limits on common pollutants like nitrogen, phosphorous, and sediment that cause eutrophication in the Chesapeake Bay. Based on these pollutant loads, states have the responsibility for reaching the reduction goals to achieve a cleaner Bay by 2025. Out of all major watersheds draining to the Chesapeake Bay, the Susquehanna River Basin provides 55% of the Bay’s total freshwater. Approximately 46% of Pennsylvania’s land area is in the Susquehanna River Basin and overall Pennsylvania contributes 44%, 24% and 32% of total nitrogen, phosphorus, and sediment to the Bay as of 2010. Within those contributions, agriculture is one of the largest sources for each pollutant. Each state created Watershed Implementation Plans (WIPs) that outline how reduction goals will be reached through conservation practice implementation. During the 2017 Midpoint Assessment, the EPA found that Pennsylvania failed to reach target nitrogen goals by 24.67%. Further, Pennsylvania’s 2019 Phase III WIP was found to not account for 4.45 million kilograms of nitrogen. Requiring a resubmission of their Phase III WIP in 2021, the EPA in 2022 believed that PA could achieve 72%, 99%, and 93% of their target reduction goals for nitrogen, phosphorus and sediment respectively. With nitrogen and sediment goals not being reached, the EPA suggested the acceleration of conservation practice installation, like riparian forest buffers, and an increase in federal oversight. As a best management practice, riparian forest buffers effectively filter pollutants from upslope areas in their watershed. By decreasing the velocity of surface runoff, buffers allow for infiltration and sediment deposition to occur. This reduces the transport of nitrogen and phosphorus into the Bay. Planted vegetation, soil sorption, and microbial communities within buffers use, retain, and remove nutrients, preventing them from moving into deeper groundwater or running off into surface water bodies. Pennsylvania has over 78,000 kilometers of streams in the Susquehanna River Basin with approximately 196.2 kilometers squared (km2) currently buffered. To reach their Phase III WIP goals, it is estimated that by 2025, 362.7 km2 would need to be buffered. Traditional designs for riparian buffers use an assumed uniform sheet flow for maximizing their effective buffer area. While ideal, this is commonly not the reality for buffers. Since riparian buffers are on the lowest portion of the watershed, typically providing ample distance for sheet flow to accumulate, most of the water entering riparian buffers occurs in concentrated flow paths (CFPs). These CFPs often form rills and gullies and negatively impact the efficacy of riparian forest buffers by reducing the effective buffer width. In some cases, these CFPs can also create gullies in riparian buffers, thus exporting more sediment and nutrients to watersheds instead of capturing these pollutants. CFPs undermine the ability of riparian buffers to help meet the 2025 Chesapeake Bay nutrient and sediment reduction goals. To properly reach target reduction goals, a means to address CFPs is critical. One soil amendment known as biochar may have the potential to do so. Currently associated with NRCS Conservation Practice Code 336, biochar helps improve soil aggregate stability, soil carbon, and soil organism habitat. Laboratory research has shown that biochar may increase soil water infiltration rates too. It is this mechanism that this research intends to investigate.