Soil microbial community characteristics in a vineyard ten years after fumigation

Authors: Rana Dangi, Sadikshya; Wang, Dong

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2020
Publication Date: 4/5/2021
Publication URL: https://handle.nal.usda.gov/10113/7709327
Citation: Rana Dangi, S., Wang, D. 2021. Soil microbial community characteristics in a vineyard ten years after fumigation. Soil Science Society of America Journal. 1-17. https://doi.org/10.1002/saj2.20186.
DOI: https://doi.org/10.1002/saj2.20186

Interpretive Summary: Soil microorganisms play important roles in organic matter decomposition, soil structure, soil quality, nutrient cycling, water and plant nutrient uptake; and it is important for them to recover after treatment with biocidal soil fumigants for the development of long-term health of agricultural soils. In this research, microbial community biomass and structure were determined in a vineyard soil at 10 years after soil fumigation. Results showed an impact of fumigation on bacterial communities, however, impact on fungal communities was not evident after ten years. The study should provide a useful guide on applying soil fumigation for high-valued tree or vine crops.

Technical Abstract: California is the number one producer of grapes in the United States, accounting for 85 percent of the total tonnage produced and nearly 90 percent of the production value. Soil fumigation has been used to control soil-borne plant pathogens, nematodes and weeds. However, broad biocidal activity of fumigants can potentially have a negative impact on native soil microbial populations. Given the numerous roles of microorganisms in the soil system, it is important to assess the impact of fumigation on soil microbial communities. Research on long-term impact and recovery of fumigation on beneficial soil microorganisms is lacking. The main objective of this research was to study the long-term impact and recovery of microbial communities in grapevine replant situations after fumigation. Soil treatments included shank injected methyl bromide (MeBr) at 448 kg ha-1 rate with high density polyethylene film (HDPE) soil cover, Telone C35 at 305 and 610 kg ha-1 rate with or without virtually impermeable film (VIF), subsurface drip application of InLine at 305 kg ha-1 rate with or without VIF, non-fumigated control and mustard cover crop in two side-by side field experiments fumigated in 2007 and 2008, respectively. Microbial community biomass in 2017 and 2018 did not differ significantly between fumigated and non-fumigated plots at the 0-30 cm depth. However, plots with shank- injected MeBr and Telone C35 applied in 2008 showed significantly reduced microbial biomass in 2018 at the deeper depth compared to subsurface drip applied InLine plots with or without VIF and non-fumigated plots. Differences between non-fumigated and fumigated plots were observed in the studied microbial communities such as gram-positive bacteria in the surface depth. The concentrations of total phospholipid fatty acids and the biomarkers for gram-positive bacteria, gram-negative bacteria and actinomycetes were significantly lower in deeper depths. However, concentrations of fungal and arbuscular mycorrhizal fungal (AMF) biomarkers did not show any significant effects with depths. Results show an impact of fumigation on bacterial communities, however, impact on fungal and AMF communities were not evident after ten years. Also, the effect of depth was apparent on bacterial communities compared to fungal and AMF communities. These data suggest that deep rooted grapevines strongly influenced fungal populations which likely supplied labile carbon to fungi through fine root turnover and root exudation in both fumigated and non-fumigated plots. In future research, it is equally vital to focus collectively on the effects of different treatments on fruit quality and yield in vineyard, as well as on the long-term effect on soil microbial community composition and biomass after fumigation.