Analyzing impacts of swine manure application on soil microbial communities and associated drainage water

Authors: RIEKE, ELIZABETH - Iowa State University; Moorman, Thomas; SOUPIR, MICHELLE - Iowa State University; YANG, FAN - Iowa State University; HOWE, ADINA - Iowa State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/12/2018
Publication Date: 8/12/2018
Citation: Rieke, E.L., Moorman, T.B., Soupir, M.L., Yang, F., Howe, A. 2018. Analyzing impacts of swine manure application on soil microbial communities and associated drainage water. In: Proceedings of International Society for Microbial Ecology annual meeting, August 12-17, 2018, Leipzig, Germany.

Interpretive Summary:

Technical Abstract: Rising demands for pork products worldwide has led to increased production in the United States. Increasing demands, coupled with production shifting towards confined animal feeding operations, has resulted in increased availability of manure, as well as a need for its disposal. Swine manure contains valuable nutrients and is often applied to agricultural land as an alternative to inorganic fertilizer. However, little is known regarding the effect of manure application on soil microbial communities and associated drainage waters. Using intact soil columns, we simulated an agroecosystem with artificial subsurface drainage, typical of the Upper Midwestern United States. Columns were collected from plots maintained in corn-soybean rotations, with nitrogen application prior to the corn growing season. Nitrogen was applied either in the form of swine manure or urea ammonium nitrate (UAN) and plots were maintained under chisel plow or no-till managements, creating four different overall management practices: manured no-till, non-manured no-till, manured chisel plow and non-manured chisel plow. Manure was applied to columns to simulate manure injection bands. DNA extraction was performed on effluent of six simulated rainfall events, replicating the length of a typical drainage season for the location (108 days). After the second, fourth and sixth rainfall events, subsets of manured columns were destructively sampled from the top 15 cm of soil for DNA extraction. Targeted 16S rRNA gene sequencing was used to characterize and to identify shifts in soil and drainage microbial communities post manure application. Our results indicated that soil history was associated with significant differences in community structure, although only 2% of variation was explained by this factor. Overall, sequences associated with 12 orders of bacteria were responsible for the majority of OTUs stimulated by manure application. Orders belonging to Proteobacteria were most prevalent, followed by Bacteroidetes, Firmicutes, Actinobacteria and Spirochaetes. While the majority of the 12 orders began to decrease prior to the end of the experiment, relative abundances of genes associated with Rhizobiales and Actinomyecetales in soil increased. The orders of bacteria in soil which were stimulated by manure application contained varied responses in drainage waters over the course of the experiment. We also identified a “manure-specific core” of five genera who comprised 13% of manure communities. Of these five genera, Clostridium sensu stricto was the only genera which did not return to pre-manure relative abundances in soil by the end of the experiment. Results from our study increase our understanding of soils’ capacity to attenuate or transport manure associated microbial communities. Identification of manure stimulated and manure derived bacteria in soil and drainage waters provides a holistic approach for tracking manure associated microbial impacts in the environment.