The Impact of Biofumigation and Chemical Fumigation Methods on the Structure and Function of the Soil Microbial Community (original) (raw)
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Application of organic amendments to restore degraded soil: effects on soil microbial properties
Environmental Monitoring and Assessment, 2015
Topsoil removal, compaction, and other practices in urban and industrial landscapes can degrade soil and soil ecosystem services. There is growing interest to remediate these for recreational and residential purposes, and urban waste materials offers potential to improve degraded soils. Therefore, the objective of this study was to compare the effects of urban waste products on microbial properties of a degraded industrial soil. The soil amendments were vegetative yard waste compost (VC), biosolids (BioS), and a designer mix (DM) containing BioS, biochar (BC), and drinking water treatment residual (WTR). The experiment had a completely randomized design with following treatments initiated in 2009: control soil, VC, BioS-1 (202 Mg ha −1), BioS-2 (403 Mg ha −1), and DM (202 Mg BioS ha −1 plus BC and WTR). Soils (0-15-cm depth) were sampled in 2009, 2010, and 2011 and analyzed for enzyme activities (arylsulfatase, β-glucosaminidase, β-glucosidase, acid phosphatase, fluorescein diacetate, and urease) and soil microbial community structure using phospholipid fatty acid analysis (PLFA). In general, all organic amendments increased enzyme activities in 2009 with BioS treatments having the highest activity. However, this was followed by a decline in enzyme activities by 2011 that were still significantly higher than control. The fungal PLFA biomarkers were highest in the BioS treatments, whereas the control soil had the highest levels of the PLFA stress markers (P<0.10). In conclusion, one-time addition of VC or BioS was most effective on enzyme activities; the BioS treatment significantly increased fungal biomass over the other treatments; addition of BioS to soils decreased microbial stress levels; and microbial measures showed no statistical differences between BioS and VC treatments after 3 years of treatment.
Scientific Reports, 2020
Agriculture is changing to rely on agroecological practices that take into account biodiversity, and the ecological processes occurring in soils. The use of agricultural biostimulants has emerged as a valid alternative to chemicals to indirectly sustain plant growth and productivity. Certain BS have been shown to select and stimulate plant beneficial soil microorganisms. However, there is a lack of knowledge on the effects and way of action of the biostimulants operating on soil functioning as well as on the extent and dynamic of these effects. In this study we aimed to decipher the way of action of a seaweed and amino-acids based biostimulant intended to be applied on soil crop residues to increase their microbial mineralization and the further release of nutrients. By setting-up a two-phase experiment (soil plant-growing and soil incubation), our objectives were to (1) determine the effects of the soil biostimulant over time on the active soil bacteria and fungi and the consequenc...
Journal of Environmental Science and Health, Part B, 2010
Rhizosphere and phyllosphere microbial communities were evaluated on roots and leaves of growth chamber-grown lettuce (Lactuca sativa (L.) cv. Green Forest) plants by culture-dependent and-independent methods after soil fumigation. Denaturing gradient gel electrophoresis (DGGE) with 16S rRNA primers followed by cloning and sequencing was used to identify major rRNA bands from the rhizosphere and phyllosphere. Three weeks after fumigation, there were no differences (P = 0.16) in rhizosphere microbial communities between the fumigated treatments and the control. The same effect was observed during week seven after fumigation (P = 0.49). Also, no significant differences (P = 0.49) were found in the phyllosphere microbial communities between the fumigated treatments and the control during the growth period of the plant. A majority of the bands in the rhizosphere were related to known bacterial sequences with a 96 to 100 % sequence similarity. Some of the derived sequences were related to Pseudomonas syringae pv. tomato DC300 and Bradyrhizobium japonicum USDA 110. A total of 23 isolates were identified from leaf surface by both culturedependent and independent methods, and only Photorhabdus luminescens was found on leaf surface using both techniques. All the Biolog isolates from phyllosphere were from the Proteobacteria phylum compared to the culture-independent bands from the leaves that were from different bacterial phyla. Based on our data, methyl bromide (MeBr) and methyl iodide (MeI) did not have any significant negative effects on rhizosphere and phyllosphere microbial communities throughout the growing period of lettuce.
Applied Soil Ecology, 2018
Anaerobic soil disinfestation (ASD), a potential alternative to pre-plant chemical fumigation for controlling soilborne pathogens, has been demonstrated in several agricultural production systems. The effect of ASD on the soil microbial community is considered one of the major factors responsible for pathogen suppression. However, rather limited information is available regarding the response of the soil microbial community to ASD throughout the cropping season, particularly in sandy soils. A field experiment was conducted to optimize the ASD technique for tomato production in Florida, utilizing two rates of molasses and composted poultry litter (CPL), and a pre-emergent herbicide application. The pre-plant soil treatments included ASD with 6.9 m 3 ha −1 of molasses and 11 Mg ha −1 of CPL (ASD0.5), ASD with 13.9 m 3 ha −1 of molasses and 22 Mg ha −1 of CPL (ASD1.0), and chemical soil fumigation control (CSF). The herbicide treatments included with and without halosulfuron application. Soil microbial community composition was monitored using phospholipid fatty acid (PLFA) analysis during the fall 2015 tomato production season. Halosulfuron application did not result in changes in the soil microbial community during the season. CSF led to significantly lower levels of bulk soil total microbial biomass, Gram negative bacteria, Gram positive bacteria and actinomycetes, compared to the ASD treatments. However, the rhizosphere effect of plants under CSF alleviated the microbial suppression and stimulated the growth of Gram negative bacteria and protozoa to reach similar levels to that of rhizosphere soils under the ASD treatments. Compared to 0 day after transplanting (DAT), Gram positive bacteria in bulk soils under the three pre-plant soil treatments significantly decreased while the fungi:bacteria ratio in bulk soils under CSF significantly increased at 36 DAT, and then remained stable throughout the season. Despite the similar microbial composition in bulk and rhizosphere soils between the two ASD treatments, the dynamic changes of some biomarker groups in bulk soils during 0-99 DAT showed distinct patterns particularly for total microbial biomass, Gram negative bacteria, actinomycetes, and fungi. Compared to 0 DAT, bulk soil microbial community composition shifted after 36 DAT under all soil treatments and remained stable until the end of the season. The changes in soil microbial community composition over time were related to changes in soil nutrient availability.
Microbial populations and enzyme activities in soils fumigated with methyl bromide alternatives
2005
fungal pathogens, but is not as effective against nematodes as MeBr (Wilhelm and Pavlou, 1980). Therefore, Methyl bromide (MeBr; CH 3 Br) use for soil fumigation will be a mixture of MeBr and CP is usually applied to control banned in 2005 due to its ozone depleting properties. Potential alternasoil-borne fungal pathogens such as Verticillium wilt tive chemicals to replace MeBr include chloropicrin (CP; CCl 3 NO 2), (Verticillium dahliae Kleb.) and weeds (Wilhelm et al., 1,3-dichloropropene (1,3-D; C 3 H 4 Cl 2), iodomethane (IM; CH 3 I), and propargyl bromide (PrBr; C 3 H 3 Br). The goal of this research was to 1961). Recent research found that an emulsifiable conassess changes in soil fungal populations, microbial biomass C (MB C) centrate (EC) formulation of CP applied through drip and respiration, nitrification potential, and enzyme activities after irrigation systems at rates Ͼ 200 kg ha Ϫ1 provided consisfumigation with MeBr and alternative fumigants. Four formulations tent cost-effective pest and weed control in strawberry of alternative fumigants (CP, InLine [61% 1,3-D plus 33% CP], Midas
Soil Microbial Community Structure and Target Organisms under Different Fumigation Treatments
Applied and Environmental Soil Science, 2015
Producers of several high-value crops in California rely heavily on soil fumigants to control key diseases, nematodes, and weeds. Fumigants with broad biocidal activity can affect both target and nontarget soil microorganisms. The ability of nontarget soil microorganisms to recover after fumigation treatment is critical because they play an important role in sustaining the health of agricultural and natural soil systems. Fumigation trial was conducted in Parlier, CA, and the study focuses on the effects of different rates of Telone C35 and also methyl bromide fumigation with polyethylene (PE) and totally impermeable film (TIF) tarps on target and nontarget soil microorganisms using field samples. Results indicated that the populations of target organisms, such as Fusarium oxysporum and Pythium spp., were reduced at all rates of fumigants. Phospholipid fatty acid (PLFA) analysis indicated that all major nontarget soil microbial groups such as Gram positive bacteria, Gram negative bacteria, fungi, and arbuscular mycorrhizal fungi (AMF) were affected by methyl bromide (MeBr) fumigation treatment. In general, the effects of Telone C35 (299 L/ha) under PE tarp had the least impact on microbial community structure and better effect on controlling target microorganisms and, therefore, indicated the better option among fumigation treatments.
Soil Biology and Biochemistry, 1997
Snnnnary-A variety of common soil microbial analyses (biomass by fumigation-extraction, basal-and substrate-induced respiration, various enzymatic activities, potential nitrification, ninhydrin-reactive nitrogen) were carried out to study the usefulness of phospholipid fatty acids (PLFAs) to detect changes in microbial activity and biomass. Soil fumigation with chloroform was used to disturb microbial activity. The total amount of PLFAs decreased by about 50% during 10 days' incubation after fumigation. In comparison with the other methods, the amount of ester-linked PLFAs gave higher estimations for microbial biomass decline. Additionally, we studied the effects of chloroform fumigation on various PLFA fractions that can be used as indicators for certain microbial subgroups. The branched chain fatty acids indicative of Gram-positive bacteria were affected only slightly (ca. 30%), whereas the monounsaturated fatty acids, mostly characteristic of certain Gram-negative bacteria, were more heavily affected (60-70%). The polyunsaturated fatty acids indicative of eukaryotes had decreased by 7&80%. The non ester-linked PLFAs and the hydroxy-substituted fatty acids of lipopolysaccharides were not affected by chloroform fumigation treatments. The methods commonly used for soil microbial biomass measurements gave diverse results after a strong decline of the microbial community. 0 1997
Biofumigation: Opportunities and Challenges for Control of Soilborne Diseases in Nursery Production
Plant Health Progress
Soilborne diseases reduce crop performance, increase costs to the nursery producers, and can cause potential ecological damage to the natural environment. In particular, soilborne diseases caused by Phytophthora nicotianae and Rhizoctonia solani are the most economically important problems of southeastern U.S. nursery producers. Methyl bromide was widely used as a standard treatment in many parts of the world until the implementation of the Montreal Protocol. Since then, many chemical and nonchemical soilborne disease management methods have been tested but are not yet providing effective and consistent results like methyl bromide. Cover crops that belong to the Brassicaceae family can be incorporated into the soil to control soilborne diseases, and this process is widely known as biofumigation. Glucosinolates that are available inside Brassicaceae plant cells can be hydrolyzed into isothiocyanates, and these compounds are proven to be highly biocidal to many microorganisms (includi...
Plant-microbe Interactions in Rhizospheric soil Treated with Different Quality Organic Residues
Journal of Pure and Applied Microbiology, 2021
The objective of this research was to study plant-microbe interactions in rhizospheric soil treated with different quality organic residues in short-term incubation of the soil and subsequent planting of maize crop. The treatments combinations were, 1) untreated soil (control; CT), 2) groundnut stover (GN) with high nitrogen (N) but low lignin (L) and polyphenol (PP), 3) tamarind leaf and petiole litter (TM) with medium N, L and PP, 4) rice straw (RS) with low N, L and PP but high cellulose, 5) GN+TM, 6) GN+RS and 7) TM+RS. Single and mixed residue additions of GN and TM, both high and intermediate quality, resulted in higher soil microbial properties and nutrients than the application of RS as a low quality. Accordingly, the application of the former group increased microbial abundances (i.e., bacteria, archaea, and fungi), elevated the enzymes related to the decomposition of organic residue (i.e., invertase, protease, phenoloxidase and peroxidase activity), and enhanced soil nutri...
Biological amendments consisting of suspensions of selected microorganisms are often used in conjunction with various organic materials for amending soils to improve soil quality and plant growth. The effects of the biological amendment on chemical and biological properties of soil were investigated for a biological amendmentalone and when combined with different organic materials includingmunicipal compost (MC), poultry litter (PL), and cover crops (red clover (RC) and spring oats). A liquid preparation of a biological amendment called Effective Microorganisms was sprayed on the tested plots three times over a two-year period. Effective Microorganisms alone did not influence pH, K, or organic matter content in soil. However, increases in P in PL-treated soils in fall of both years andCa in MC-treated soil in fall 2001, and decreases in Ca, Mg, and cation exchange capacity (CEC) in RC-planted soil were associated with EM. Increased dehydrogenase(DH) activitiesassociated with Effective Microorganismswere only detected in July (P=0.0222) and October (P=0.0834) for RC-planted soils in the first year. Fluorescein diacetate (FDA) hydrolysisappeared to be enhanced by Effective Microorganisms in soils untreated or treated with MC and oatsbut only sporadically during the sampling period. FDA hydrolysis in both PL-and RC-treated soils as well as DH activity in PL-treated soils decreased with Effective Microorganisms treatment. Effective Microorganisms did not influence substrate utilization patterns expressed by the BIOLOG assay. We conclude that Effective Microorganisms effects on soil chemical and biological properties varied depending on the added organic materials. Effective Microorganisms periodically increased soil DH activity and FDA hydrolysis with RC and with MC plus oats, respectively.