Dust-associated microbiomes from dryland wheat fields differ with tillage practice and biosolids application

Authors: Schlatter, Daniel; SCHILLINGER, WILLIAM - Washington State University; BARY, ANDY - Washington State University Extension Service; Sharratt, Brenton; Paulitz, Timothy

Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2018
Publication Date: 7/1/2018
Citation: Schlatter, D.C., Schillinger, W.F., Bary, A.I., Sharratt, B.S., Paulitz, T.C. 2018. Dust-associated microbiomes from dryland wheat fields differ with tillage practice and biosolids application. Atmospheric Environment. 185:29-40.

Interpretive Summary: Dust from agricultural fields can be a health concern, especially small particles (PM10) that are generated in areas of eastern Washington with high wind erosion potential. Biosolids are being increasingly used as a fertilizer on dryland wheat farms in Eastern Washington. Biosolids are the product of municipal sewage treatment, and contain high levels of nitrogen and organic matter. Next-generation sequencing was used to describe the microbial communities (fungi and bacteria) in dust from wheat fields treated with biosolids. We also tested the effects of two kinds of tillage- conservation (with the use of an undercutter) and conventional (incorporated with a rototill). The microbial communities in dust from wheat fields treated with biosolids vs synthetic fertilizer were different, as were communities comparing conservation vs conventional tillage. The bacterial families, Clostridiaceae and Enterobacteriaceae, potential bacterial human pathogens from biosolids, were extremely rare, but Clostridiaceae was significantly enriched in biosolids treatments.

Technical Abstract: Wind erosion is a significant threat to the productivity and sustainability of agricultural soils. In the dryland winter wheat (Triticum aestivum L.)-fallow region of Inland Pacific Northwest of the USA (PNW), farmers increasingly use conservation tillage practices to control wind erosion. In addition, some farmers in this dry region apply municipal biosolids to soils as fertilizer and a source of stable organic matter. The impacts of soil management practices on emissions of dust microbiota to the atmosphere are unknown. We used high-throughput DNA sequencing to examine the impacts of conservation tillage and biosolids amendments on the transport of dust-associated fungal and bacterial communities during simulated high-wind events over two years at Lind, WA. The fungal and bacterial communities contained in windblown dust differed significantly with tillage (conservation vs. conventional) and fertilizer (synthetic vs. biosolids) treatments. However, the richness and diversity of fungal and bacterial communities of dust did not vary significantly with tillage or fertilizer treatments. Taxa enriched in dust from fields under conservation tillage represented many plant-associated taxa that likely grow on residue left on the soil surface, whereas taxa that were more abundant with conventional tillage were those that likely grow on buried plant residue. Dust from biosolids-amended fields harbored greater abundances of taxa that likely feed on introduced carbon. Most human-associated taxa that may pose a health risk were not present in dust after biosolids amendment, although members of Clostridiaceae were enriched with this treatment. Results show that tillage and fertilizer management practices impact the composition of bioaerosols emitted during high-wind events, and has potential implications for plant and human health.