Potassium is a crucial macronutrient essential for plant health and productivity. Although potassium is present in soil, a significant portion is tightly bound within mineral structures, rendering it unavailable to plants. This limitation necessitates the widespread use of potassium-based fertilizers. However, the continuous removal of plants from ecosystems often depletes potassium levels in the soil faster than they can be naturally replenished, and the production of these fertilizers also contributes to greenhouse gas emissions. Therefore, developing sustainable methods to enhance potassium availability in soils is imperative.
Fortunately, both plants and microbes possess the ability to weather mineral surfaces and access nutrients, including potassium, through mechanical and chemical processes. Despite this, the molecular mechanisms involved in potassium sourcing, uptake, storage, transport, and transfer by plants and microbes remain poorly understood. Addressing these gaps in knowledge is crucial for advancing sustainable agricultural practices and reducing our reliance on environmentally damaging fertilizers. We have several projects to improve our understanding of potassium rhizosphere biogeochemical processes:
1.) Plant-microbe sourcing of K from feldspar and the impact of drought
2.) Fungal mechanisms of K translocation
3.) Potassium mineral weathering
4.) Potassium chemistry in soils and sediments from the last thermal maximum
1.) Plant-microbe sourcing of K from feldspar and the impact of drought
2.) Fungal mechanisms of K translocation
3.) Potassium mineral weathering
4.) Potassium chemistry in soils and sediments from the last thermal maximum
Potassium Rhizosphere Dynamics
We are studying the effect of moisture variation on the uptake and transformations of K between the soil fungus Fusarium sp. DS 682, bacterium Bacillus subtilis and model crop Brachypodium distachyon using EMSL TerraForms. During low moisture, microbial access to diffusion based nutrient translocation in pore water becomes limited due to decreased pore water connectivity. Consequently, microbes may access critical nutrients through mineral (i.e. fixed K in mineral structures) weathering. This project is in collaboration with Arunima Bhattacharjee (EMSL).
We are studying the effect of moisture variation on the uptake and transformations of K between the soil fungus Fusarium sp. DS 682, bacterium Bacillus subtilis and model crop Brachypodium distachyon using EMSL TerraForms. During low moisture, microbial access to diffusion based nutrient translocation in pore water becomes limited due to decreased pore water connectivity. Consequently, microbes may access critical nutrients through mineral (i.e. fixed K in mineral structures) weathering. This project is in collaboration with Arunima Bhattacharjee (EMSL).
Potassium Sourcing and Translocation by Fungi
Fungi are known to form various beneficial relationships with plants. Several fungal species are also known potassium solubilizing microbes. However, the various mechanisms of potassium sourcing, uptake and even transfer to plant hosts is largely unknown and assumed to be solvated K+ ions.
Working with several different groups we are studying how saprotrophic, ectomycorrhizal and arbuscular mycorrhizal fungi to study: (1) what form of K chemistries accumulate in these fungi; (2) whether the external nutrient availability impacts K uptake by hyphae, (3) what impact plant roots have on fungal K accumulation and movement, and (4) what impact these fungi have on weathering minerals.
Collaborators include Arunima Bhattacharjee (EMSL), Kevin Garcia (NCSU), Erin Nuccio (LLNL).
Fungi are known to form various beneficial relationships with plants. Several fungal species are also known potassium solubilizing microbes. However, the various mechanisms of potassium sourcing, uptake and even transfer to plant hosts is largely unknown and assumed to be solvated K+ ions.
Working with several different groups we are studying how saprotrophic, ectomycorrhizal and arbuscular mycorrhizal fungi to study: (1) what form of K chemistries accumulate in these fungi; (2) whether the external nutrient availability impacts K uptake by hyphae, (3) what impact plant roots have on fungal K accumulation and movement, and (4) what impact these fungi have on weathering minerals.
Collaborators include Arunima Bhattacharjee (EMSL), Kevin Garcia (NCSU), Erin Nuccio (LLNL).
Potassium Mineral Weathering
Potassium XAS is uncommon in environmental science, particularly when compared to P, S, Mn and Fe. However, K XAS of both biological compounds and minerals is interesting despite K always in the +1 oxidation state and similar first shell bonding environments. While some researchers are applying K XAS to environmental systems such as soils, we lack a fundamental understanding of the electronic transitions that give rise to K spectral differences.
In collaboration with Josh Kas (U. Washington) we are combining XAS and theory tools (primarily full multiple scattering) to understand how mineral weathering can impact K XAS from complex environmental samples.
Potassium XAS is uncommon in environmental science, particularly when compared to P, S, Mn and Fe. However, K XAS of both biological compounds and minerals is interesting despite K always in the +1 oxidation state and similar first shell bonding environments. While some researchers are applying K XAS to environmental systems such as soils, we lack a fundamental understanding of the electronic transitions that give rise to K spectral differences.
In collaboration with Josh Kas (U. Washington) we are combining XAS and theory tools (primarily full multiple scattering) to understand how mineral weathering can impact K XAS from complex environmental samples.
