Unraveling mechanisms behind reduced nitrate leaching with graphite nanomaterials addition with fertilizers in soil column experiments

Partho Das; C Ryan Penton; Yuqiang Bi; Paul Westerhoff

doi:10.1016/j.chemosphere.2023.139417

Unraveling mechanisms behind reduced nitrate leaching with graphite nanomaterials addition with fertilizers in soil column experiments

Chemosphere. 2023 Oct:337:139417. doi: 10.1016/j.chemosphere.2023.139417. Epub 2023 Jul 5.

Authors

Partho Das¹, C Ryan Penton², Yuqiang Bi³, Paul Westerhoff⁴

Affiliations

¹ School of Sustainable Engineering and the Built Environment, Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ, USA.
² College of Integrative Sciences and Arts, Arizona State University, Mesa, AZ, USA; Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, AZ, USA.
³ School of Sustainable Engineering and the Built Environment, Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ, USA. Electronic address: yuqiangb@asu.edu.
⁴ School of Sustainable Engineering and the Built Environment, Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ, USA. Electronic address: p.westerhoff@asu.edu.

PMID: 37419157
DOI: 10.1016/j.chemosphere.2023.139417

Abstract

Overuse or mistimed application of nitrogen fertilizer can cause nitrate contamination in groundwater and surrounding surface waters. Previous greenhouse studies have explored the use of graphene nanomaterials, including graphite nano additive (GNA), to reduce nitrate leaching in an agricultural soil while growing lettuce crops. To investigate the mechanism of GNA addition in suppressing nitrate leaching, we conducted soil column experiments using native agricultural soils under saturated or unsaturated flow conditions to simulate varied irrigation. We investigated the effects of temperature (4 °C compared with 20 °C) on microbial activity and dose effect of GNA was also explored (165 mg/kg soil and 1650 mg/kg soil) for biotic soil column experiments whereas a single temperature condition (20 °C) and GNA dose (165 mg/kg soil) was employed for abiotic (autoclaved) soil column experiments. Results showed GNA addition had minimal effects on nitrate leaching in saturated flow soil columns due to short hydraulic residence times (∼3.5 h). In comparison, longer residence times (∼3 d) in unsaturated soil columns reduced nitrate leaching by 25-31% relative to control soil columns without GNA addition. Furthermore, nitrate retention in the soil column was found to be suppressed at 4 °C compared with 20 °C, suggesting a bio-mediated mechanism for GNA addition to reduce nitrate leaching. In addition, the soil dissolved organic matter was found to be associated with nitrate leaching, where less nitrate leaching occurring when higher dissolved organic carbon (DOC) was measured in leachate water. Following studies of adding soil-derived organic carbon (SOC) resulted in greater nitrogen retention in the unsaturated soil columns only when GNA was present. Overall, the results suggest that GNA-amended soil reduces nitrate loss through increased N immobilization in the microbial biomass or loss of N in gaseous phase through enhanced nitrification and denitrification process.

Keywords: Agriculture; Fertilizer; Graphene; Groundwater; Nanotechnology; Nitrate pollution.

MeSH terms

Agriculture / methods
Fertilizers
Graphite*
Nitrates / analysis
Nitrogen / analysis
Soil*

Substances

Soil
Nitrates
Graphite
Fertilizers
Nitrogen