An In-Situ Study Design to Assess Removal of Excess Nutrients from Agricultural Runoff by Fungi in Conservation Buffers

Abstract

Nutrients from agricultural runoff are a leading source of freshwater pollution. Numerous rivers and lakes in Montana contain elevated nutrient levels, increased harmful algae blooms, and disrupted aquatic ecosystems. Conservation buffers are a widely accepted strategy to intercept runoff and mitigate nutrient loading to aquatic systems. Fungi are also known for facilitating key ecosystem functions such as pollutant removal and nutrient cycling; therefore, fungal enhancement of conservation buffers may increase nutrient uptake and reduce nutrient loads in aquatic systems. Yet, fungi are not commonly incorporated into conservation buffers, and their role in enhancing phytoremediation of elevated nutrient concentrations remains unclear. However, numerous studies have demonstrated that excess nutrients decrease above- and below ground biodiversity, which impacts plant productivity, nutrient acquisition, water retention, and pathogen and disease resistance. Thus, despite naturally occurring microbial communities, conservation buffers within a degraded landscape might need enhanced with fungi to promote or maintain productivity. The objective of my paper is to present an in-situ experimental design intendent to resolve this knowledge gap. I conducted a watershed analysis to find a location within the Upper Missouri River Watershed suitable for restoration based on land use, land ownership, hydrologic context, water quality, and amount of overland flow across agricultural land. I synthesized over 35 articles to create a site-specific design intended to experimentally test whether incorporating fungi into conservation buffers will (1) promote nutrient uptake in plants, despite nutrient saturated conditions and (2) reduce soil nitrate leaching. The metrics for evaluation are foliar nitrogen and phosphorus concentrations and soil nitrate levels using ion exchange resin capsules. In this design, five of ten conservation buffers are treated with fungi and monitored long term to quantify and compare the response ratios of the treatment to the control plots. The response ratios will reveal the degree of effectiveness of the treatment and whether buffers need enhanced with fungi to retain nutrients. In-situ studies of fungi-enhanced phytoremediation are lacking, and fungi are greatly underutilized and overlooked as an effective tool in restoration of excess nutrients. As a headwaters state that ranks high in agricultural production, Montana’s contribution to water quality degradation is increasingly being unveiled. Results from this study could be used as a remediation tool to improve conservation buffer effectiveness to retain nutrients and mitigate nutrient pollution.