Location: Water Management Research
Title: Soil biotic and abiotic responses to dimethyl disulfide spot drip fumigation in established grape vines Authors
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 18, 2013
Publication Date: N/A
Interpretive Summary: Soil fumigants have been extensively used to control target soil borne pathogens and weeds. Fumigants including dimethyl disulfide (DMDS) with their broad biocidal activity can affect both target and non-target organisms in soil. Soil microbial communities are known to provide essential ecosystem services such as nutrient cycling, nitrogen fixation, soil aggregation and erosion control, organic matter decomposition and suppression of pests and diseases. Also, abiotic factors play a major role in nutrient uptake and multiple physical and chemical reactions that affect the plant’s root system. Therefore, it is important to know how the ecologically important microbial communities and soil abiotic factors recover after fumigation. Studies on the effect of DMDS on microbial community structure and on abiotic factors such as macronutrients, total carbon, total nitrogen and dissolved organic carbon, etc., are currently unknown. In this study, DMDS was applied in microplot and field trials and soil samples were collected after 15, 45, 60 and 90 days after fumigation. The effects of fumigation on plant parasitic nematodes as well as the recovery of soil microbial communities and abiotic factors were studied. All major non-target soil microbial groups decreased significantly 15 days after fumigation. Fumigation with DMDS did not impact the availability of macronutrients and microbial community biomass and structure but was effective for the control of plant parasitic nematode. Study concluded that the changes in microbial communities were mainly due to environmental factors. The results will be helpful to growers who need to make decisions regarding the efficacy of DMDS fumigation in the future.
Technical Abstract: Dimethyl disulfide (DMDS) is a soil fumigant used in agricultural systems as an alternative to methyl bromide (MeBr) for the control of soilborne pests and pathogens. However, fumigants including DMDS that have broad biocidal activity can affect both target and non-target organisms in soil. Many biotic factors such as microorganisms in soil are vital for nutrient cycling, organic matter decomposition, plant nutrient uptake, and maintenance of soil structure. Hence, it is important for ensuring the recovery of this type of microorganisms after fumigation for the development of healthy soils. Abiotic factors play a major role in nutrient uptake and multiple physical and chemical reactions that affect the plant’s root system. Therefore, it is of interest to establish the contribution of fumigants to abiotic factors change in the soil. The effect of DMDS on microbial community structure and on abiotic factors such as carbon content, calcium, etc., is currently unknown. Therefore, this study focused on the effects of DMDS on the recovery of ecologically important microbial communities and soil abiotic factors while affecting plant parasitic nematodes in both field and microplot trials. Microbial community structure using phospholipid fatty acid (PLFA) analysis indicated that total amount of PLFA as well as all major non-target soil microbial groups such as Gram positive bacteria, Gram negative bacteria, fungi, arbuscular mycorrhizal fungi (AMF) and actinomycetes decreased significantly 15 days after fumigation in the untreated control as well as in all the rates of DMDS tested in a microplot trial. Canonical multivariate analysis of variance indicated that soil microbial communities 45, 60 and 90 days after fumigation were similar to one another compared to 15 days after fumigation. The research showed that reduction and changes in microbial community biomass and structure were mainly due to environmental factors and therefore, it is concluded that DMDS fumigation did not impact the activity of beneficial microorganisms. Total nitrogen, carbon and other abiotic factors were also not affected by DMDS fumigation. Plant parasitic nematodes were greatly affected by DMDS fumigation and this interaction could be related to its mode of action which affects nematode mitochondrial activity.