Soil microbial community characteristics in a vineyard ten years after fumigation

Abstract

AbstractCalifornia is the number one producer of grapes in the United States. Soil fumigation has been used to control soilborne pests and pathogens. However, fumigants can potentially have a negative impact on native soil microbial populations. Given the roles of microorganisms in the soil system, it is important to assess the long‐term impact of fumigation on soil microbial communities, which is currently lacking. The objective of this research was to study the long‐term impact of microbial communities in grapevine (Vitis vinifera L.) replanting situations after fumigation. Soil treatments included methyl bromide (MeBr), Telone C35, InLine, a nonfumigated control, and a mustard (Sinapis alba L.) cover crop in two side‐by‐side field experiments fumigated in 2007 and 2008. Microbial community biomass in 2017 and 2018 did not differ between fumigated and nonfumigated plots at the 0‐ to 30‐cm depth. However, plots with shank‐injected MeBr and Telone C35 applied in 2008 showed significantly reduced microbial biomass in 2018 at deeper depths than subsurface drip‐applied InLine plots. The results show the impact of fumigation on bacterial communities; however, the impact on fungal and arbuscular mycorrhizal fungi (AMF) communities was not evident after 10 years. Furthermore, the effect of depth was apparent on bacterial communities compared with fungal and AMF communities. The data suggest that deep‐rooted grapevines influenced fungal populations, which probably supplied labile C in fumigated and nonfumigated plots. Future research needs to focus collectively on the long‐term effects of fumigation on fruit quality and yield in vineyards, and on soil microbial communities.