Ferrihydrite enrichment in the rhizosphere of unsaturated soil improves nutrient retention while limiting arsenic and uranium plant uptake

Authors

Arindam Malakar, University of Nebraska - LincolnFollow
Daniel D. Snow, University of Nebraska-LincolnFollow
Michael Kaiser, University of Nebraska - LincolnFollow
Jordan Shields, University of Nebraska-LincolnFollow
Bijesh Maharjan, University of Nebraska-LincolnFollow
Harkamal Walia, University of Nebraska - LincolnFollow
Daran Rudnick, University of Nebraska - LincolnFollow
Chittaranjan Ray, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2022

Citation

Published in Science of the Total Environment 806 (2022) 150967

doi:10.1016/j.scitotenv.2021.150967

Comments

Copyright © 2021 Elsevier B.V. Used by permission.

Abstract

Improvement of nutrient use efficiency and limiting trace elements such as arsenic and uranium bioavailability is critical for sustainable agriculture and food safety. Arsenic and uranium possess different properties and mobility in soils, which complicates the effort to reduce their uptake by plants. Here, we postulate that unsaturated soil amended with ferrihydrite nanominerals leads to improved nutrient retention and helps reduce uptake of these geogenic contaminants. Unsaturated soil is primarily oxic and can provide a stable environment for ferrihydrite nanominerals. To demonstrate the utility of ferrihydrite soil amendment, maize was grown in an unsaturated agricultural soil that is known to contain geogenic arsenic and uranium. The soil was maintained at a gravimetric moisture content of 15.1 ± 2.5%, typical of periodically irrigated soils of the US Corn Belt. Synthetic 2-line ferrihydrite was used in low doses as a soil amendment at three levels (0.00% w/w (control), 0.05% w/w and 0.10% w/w). Further, the irrigation water was fortified (~50 μg L^-1 each) with elevated arsenic and uranium levels. Plant dry biomass at maturity was ~13.5% higher than that grown in soil not receiving ferrihydrite, indicating positive impact of ferrihydrite on plant growth. Arsenic and uranium concentrations in maize crops (root, shoot and grain combined) were ~ 20% lower in amended soils than that in control soils. Our findings suggest that the addition of low doses of iron nanomineral soil amendment can positively influence rhizosphere geochemical processes, enhancing nutrient plant availability and reduce trace contaminants plant uptake in sprinkler irrigated agroecosystem, which is 55% of total irrigated area in the United States.