Resilience of the microbial communities of semi-arid agricultural soils during natural climatic variability events

Authors: Perez-Guzman, Lumarie; Acosta-Martinez, Veronica; PHILLIPS, LORI - Agriculture And Agri-Food Canada; Mauget, Steven

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2019
Publication Date: 1/20/2020
Citation: Perez-Guzman, L., Acosta Martinez, V., Phillips, L.A., Mauget, S.A. 2020. Resilience of the microbial communities of semi-arid agricultural soils during natural climatic variability events. Applied Soil Ecology. 149. https://doi.org/10.1016/j.apsoil.2019.103487.
DOI: https://doi.org/10.1016/j.apsoil.2019.103487

Interpretive Summary: Soil microbes play important roles in nutrient cycling and are beneficial for plant growth and overall soil health. However, changes in precipitation and temperature can affect the microbial community and their processes. This study evaluated the soil microbial component from five farms under cotton production from 2014-2018. Samplings were done during the growing season and after harvest. Although the five farms varied in irrigation practices and soil types, all responded similarly. A change from 2015 to 2016 that brought low soil moisture associated to higher soil temperatures and low precipitation caused decreases in microbial abundance and activity. Therefore, we evaluated how the microbial component recovered after this climatic event as these changes can impact crop productivity by limiting nutrients needed for plant growth.

Technical Abstract: The microbial community carry out important processes that support plant growth and maintain soil health. However, extreme climatic variability such as higher temperatures and prolonged drought may cause fluctuations in the microbial community abundance, composition, and activity, thus affecting essential functions they govern including nutrient cycling and soil organic matter (SOM) dynamics. This study evaluated five agricultural lands from the Texas High Plains semi-arid region. The sites which have been under continuous cotton (Gossypium hirsutum L.) production were sampled during the growing season and post-harvest from 2014-2018. Although sites differed in irrigation practices and soil textural class (e.g. from sandy loam to clay), all responded similarly to a decrease in precipitation, and increase in temperatures from 2015 to 2016. Microbial abundance via fatty acid methyl ester (FAME) analysis during the growing season of 2016 decreased by 82% in the sandiest soil, and by 38% in the soil with highest clay, when compared to 2015, a year of record precipitation for this region (e.g., 693 vs. 465 mm). Similarly, enzyme activities were reduced by as much as 87% (depending on the site) in the 2016 growing season when compared to 2015. The significant decreases in the soil microbial component could be explained by extremely low soil moisture (e.g. 2% in dryland; 6% irrigated sites) associated to low precipitation and high soil temperatures during the 2016 growing season (6.7 °C warmer than 2015). Furthermore, these conditions resulted in shifts in microbial composition especially significantly decreased (p < 0.05) saprophytic fungal markers by 59% (e.g., decreased from an average of 26.8 to 10.9 nmol g-1 soil). However, after 2016 all biological parameters showed increasing trends, thus demonstrating a remarkable recovery and higher resilience than expected for semiarid soils, which experience extremes in temperature, frequent droughts and have low SOM (< 1%).