Plants, People, Planet (Jul 2022)
Effects of mycorrhizae, plants, and soils on phosphorus leaching and plant uptake: Lessons learned from a mesocosm study
Abstract
Societal Impact Statement Worldwide, farmers struggle to find the most efficacious practices which balance crop fertility needs and water quality protection. Through a greenhouse experiment, we investigated how soil status (high vs. low phosphorus [P] concentration), mycorrhizae (inoculated vs. not), and plant species (dogwood vs. willow) affected P plant uptake and leaching. We found mycorrhizae did not affect uptake or leaching, more P was leached from high than low P soil, dogwood uptook yet leached more P, and above ground biomass at the end of summer contained more P than roots. This study provides insights to be considered by researchers and practitioners who implement best management practices for water quality. Summary This research examined the effects of mycorrhizal inoculation in high and low phosphorus saturation soils on phosphorus uptake by Cornus sericea and Salix niger. The aim was to identify practices that improved water quality functions of riparian buffers to protect surface waters impacted by eutrophication. A mesocosm experiment arranged as a random block design was conducted with mycorrhizal presence, soil phosphorus saturation status, and plant species as factors. Leachate, plant uptake, and soil phosphorus were measured to assess the effects. Greater leachate and uptake of phosphorus were detected for C. sericea than for S. niger. Mycorrhizae had no effects on leaching nor on uptake of phosphorus in this experiment. High phosphorus saturated soils had greater leaching and uptake than the low phosphorus soils. Above ground biomass contained more phosphorus than below ground biomass in both species at time of harvest. Estimations of phosphorus removal through coppicing suggest a very slow removal rate in biodiverse multi‐functional riparian buffers. Our results suggest that cyclical coppicing can be an improvement to Best Management Practices. Diverse riparian buffers are limited in the amount of phosphorus that they can store and mitigate, even with coppicing. The emphasis therefore should be on agricultural best management practices that reduce phosphorus export from upland fields. Further studies in phosphorus accumulating plant species with appropriate mycorrhizal symbionts are needed.
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