Culturable antibiotic‐resistant fecal coliform bacteria in soil and surface runoff after liquid dairy manure surface application and subsurface injection

Abstract

Land application of manure, while beneficial to soil health and plant growth, can lead to an overabundance of nutrients and introduction of emerging contaminants into agricultural fields. Compared with surface application of manure, subsurface injection has been shown to reduce nutrients and antibiotics in surface runoff. However, less is known about the influence of subsurface injection on the transport and persistence of antibiotic‐resistant microorganisms. We simulated rainfall to field plots at two sites (one in Virginia and one in Pennsylvania) 1 or 7 d after liquid dairy manure surface and subsurface application (56 Mg ha–1) and monitored the abundance of culturable antibiotic‐resistant fecal coliform bacteria (ARFCB) in surface runoff and soils for 45 d. We performed these tests at both sites in spring 2018 and repeated the test at the Virginia site in fall 2019. Manure subsurface injection, compared with surface application, resulted in less ARFCB in surface runoff, and this reduction was greater at Day 1 after application compared with Day 7. The reductions of ARFCB in surface runoff because of manure subsurface injection were 2.5–593 times at the Virginia site in spring 2018 and fall 2019 and 4–5 times at the Pennsylvania site in spring 2018. The ARFCB were only detectable in the 0‐to‐5‐cm soil depth within 14 d of manure surface application but remained detectable in the injection slits of manure subsurface‐injected plots even at Day 45. This study demonstrated that subsurface injection can significantly reduce surface runoff of ARFCB from manure‐applied fields.

Diagnostic study of some bacterial pollutants isolated from different food and environmental samples in the city of Mosul, Iraq

“…From Table 2, we note that the total number of coliform bacteria in the soil is also high, and the reason may be the use of organic fertilizers, poor reclamation of agricultural lands, or overgrazing and animal waste (Hilaire et al, 2022). While the irrigation water samples were less contaminated with coliform bacteria, because the water was taken from pumps that draw water from the river, meaning that the water is running and not static, so the percentage of contamination was less (Eissa et al, 2022).…”

Subsurface Manure Injection Reduces Surface Transport of Antibiotic Resistance Genes but May Create Antibiotic Resistance Hotspots in Soils

“…A balance between livestock health and reducing global antimicrobial resistance must be reached. One potential way to minimize antibiotic resistance propagation is to implement manure management strategies that maximize nutrient utilization but minimize the direct contract between manure and crops. − Manure injection strategies, in which manure is placed below the ground surface in shallow (12–25 cm deep) slits, are now known to minimize the associated risks of manure land application such as surface runoff of excess nutrients and transport of veterinary antibiotics and ARB. ,− …”

“…Subsurface injection has proven to be particularly effective at reducing transport of AREs into surface runoff after heavy rainfall when compared to surface application of manure . Le et al showed reduction of specific antimicrobials, whereas Hilaire et al showed reduction of sulfamethazine-, tetracycline-, and erythromycin-resistant Escherichia coli ( E. coli ) . Compared to manure surface application, implementation of subsurface manure injection resulted in 47%–88% reduction for sulfamerazine, chlortetracycline, pirlimycin, and tylosin and 227–593 times reduction for sulfamethazine-, tetracycline-, and erythromycin-resistant Escherichia coli ( E. coli ) in surface runoff .…”

“…Le et al showed reduction of specific antimicrobials, whereas Hilaire et al showed reduction of sulfamethazine-, tetracycline-, and erythromycin-resistant Escherichia coli ( E. coli ) . Compared to manure surface application, implementation of subsurface manure injection resulted in 47%–88% reduction for sulfamerazine, chlortetracycline, pirlimycin, and tylosin and 227–593 times reduction for sulfamethazine-, tetracycline-, and erythromycin-resistant Escherichia coli ( E. coli ) in surface runoff . However, the latter study also showed that ARB can persist up to 45 days within injection slits.…”

“…50 Compared to manure surface application, implementation of subsurface manure injection resulted in 47%−88% reduction for sulfamerazine, chlortetracycline, pirlimycin, and tylosin 46 and 227−593 times reduction for sulfamethazine-, tetracycline-, and erythromycin-resistant Escherichia coli (E. coli) in surface runoff. 50 However, the latter study also showed that ARB can persist up to 45 days within injection slits. At the same time, a previous laboratory study used shotgun metagenomic sequencing to examine the metagenomes of soils that had various amendments applied to them and found that application of manure, whether raw or composted, led to increased richness of ARGs in soils and diverse ARG types within 1 d. 52 The study also showed that application of manure with antibiotics impacts ARGs in soil for up to 120 d. Therefore, while current evidence suggests that adjusting manure application strategies may reduce environmental transport of AREs, the overall effect that manure injection has on the fate and transport of ARGs remains poorly understood.…”