Abstract
Context. Large quantities of treated sewage sludge (biosolids) are produced and beneficially applied to agricultural fields to improve soil fertility in many countries. Biosolids have extremely high concentrations of ammonium and organic matter that can be beneficial but also detrimental to the environment by promoting microbially-mediated reactions that contribute to eutrophication and greenhouse gas emission. Aims. The hypothesis of the study was that high concentrations of ammonium and labile organic matter in biosolids would significantly affect nitrogen transformations and nitrogen-cycling gene expression by different members of the prokaryotic community in a biosolids-amended agricultural soil. Methods. An organically-managed agricultural soil was amended with biosolids and monitored for changes in carbon dioxide and inorganic nitrogen species for 3 weeks under laboratory conditions. Then, RNA was extracted and compared for nitrogen-cycling gene expression levels in biosolids-amended and unamended soil. Key results. Biosolids amendment significantly increased ammonium concentration and decreased oxygen and nitrate concentrations in soil zones near biosolid particles, which coincided with significant changes in expression levels of genes for catabolic glutamate dehydrogenase, nitrification enzymes, denitrifying enzymes, and numerous other enzymes by different members of the prokaryotic community. Conclusions. The application of biosolids to soil set in motion a dynamic organic nitrogen mineralisation–nitrification–denitrification cycle between the anaerobic biosolids zone and aerobic soil zone. Implications. Biosolids-induced changes in nitrogen transformations by different members of the microbial community have implications on nitrogen availability/toxicity to nitrifying populations and plants, ammonium and nitrate in surface runoff, and nitrous oxide greenhouse gas emission from biosolids-amended soil.
| Original language | English |
|---|---|
| Article number | SR23157 |
| Journal | Soil Research |
| Volume | 62 |
| Issue number | 1 |
| DOIs | |
| State | Published - Nov 16 2023 |
Bibliographical note
Publisher Copyright:© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing.
Funding
I would like to acknowledge sponsorship from USDA National Institute of Food and Agriculture, Hatch project W4170: Beneficial Use of Residuals to Improve Soil Health and Protect Public and Ecosystem Health. My sincere appreciation goes to Mark Williams for assistance in soil collection at the University of Kentucky Horticultural Research Farm, the staff at University of Kentucky Regulatory Services for soil chemical analysis, and Vikram Gazula at the University of Kentucky High Performance Computing Centre for access and assistance in using the HPC required for bioinformatics computing.
| Funders | Funder number |
|---|---|
| University of Kentucky Horticultural Research Farm | |
| US Department of Agriculture National Institute of Food and Agriculture, Agriculture and Food Research Initiative | W4170 |
| US Department of Agriculture National Institute of Food and Agriculture, Agriculture and Food Research Initiative |
Keywords
- RNA-Seq
- archaea
- bacteria
- biosolids
- denitrification
- diffusion
- metatranscriptomics
- microbial ecology
- nitrification
- nitrogen cycling
- organic hotspot
- organic matter
- soil
ASJC Scopus subject areas
- Environmental Science (miscellaneous)
- Soil Science
- Earth-Surface Processes