Airborne bacterial emission fluxes from manure‐fertilized agricultural soil

Abstract

This is the first study to quantify the dependence on wind velocity of airborne bacterial emission fluxes from soil. It demonstrates that manure bacteria get aerosolized from fertilized soil more easily than soil bacteria, and it applies bacterial genomic sequencing for the first time to trace environmental faecal contamination back to its source in the chicken barn. We report quantitative, airborne emission fluxes of bacteria during and following the fertilization of agricultural soil with manure from broiler chickens. During the fertilization process, the concentration of airborne bacteria culturable on blood agar medium increased more than 600 000-fold, and 1 m 3 of air carried 2.9 × 10 5 viable enterococci, i.e. indicators of faecal contamination which had been undetectable in background air samples. Trajectory modelling suggested that atmospheric residence times and dispersion pathways were dependent on the time of day at which fertilization was performed. Measurements in a wind tunnel indicated that airborne bacterial emission fluxes from freshly fertilized soil under local climatic conditions on average were 100-fold higher than a previous estimate of average emissions from land. Faecal bacteria collected from soil and dust up to seven weeks after fertilization could be traced to their origins in the poultry barn by genomic sequencing. Comparative analyses of 16S rRNA gene sequences from manure, soil and dust showed that manure bacteria got aerosolized preferably, likely due to their attachment to low-density manure particles. Our data show that fertilization with manure may cause substantial increases of bacterial emissions from agricultural land. After mechanical incorporation of manure into soil, however, the associated risk of airborne infection is low.

Agricultural fertilization with poultry manure results in persistent environmental contamination with the pathogenClostridioides difficile

“…A 2.1-hectare agricultural field was fertilized with 12 tons of poultry manure from Farm 1 (Thiel et al ., 2020). Prior to fertilization, our enrichment approach failed to detect any C. difficile in soil from this field.…”

“…As a consequence, the disposal of manure or manure-derived products as fertilizer on agricultural land may lead to environmental contamination with C. difficile spores. The survival of C. difficile in fertilized agricultural soil and its release with surface water runoff or dust has as yet not been investigated, in contrast to other manure-derived pathogens (Blaustein et al ., 2015; Thiel et al ., 2020).…”

“…The spread of pathogenic bacteria can be tracked by comparing their genome sequences (Croucher et al ., 2015; Besser et al ., 2019; Thiel et al ., 2020). Within the EnteroBase platform, we have recently established a publicly accessible database for Clostridioides genomic data that currently (January 2021) contains 20,972 draft genomes and their associated metadata (Frentrup et al ., 2020).…”

A new Lagrangian in-time particle simulation module (Itpas v1) for atmospheric particle dispersion

“…Here, we use Itpas to examine the role of the diurnal ABL development to the dispersion of soil dust and organic manure dust particles, which were emitted mechanically during typical field work: The application of dry fertiliser with a spreader and the subsequent incorporation of the fertiliser with a cultivator. The field work was carried out in the framework of the SOARiAL (Spread of antibiotics resistance in an agrarian landscape) project (Thiel et al, 2020), during which airborne particle concentrations were measured as described by Münch et al (2020).…”

“…The experiment took place at an agricultural field near Müncheberg, Germany approximately 50 km east of Berlin, on 31 May 2017 (Münch et al, 2020;Thiel et al, 2020). During this day, the weather over east Germany and west Poland was dry with some shallow cumulus clouds.…”