Determination of Post Fumigation Recovery of Soil Microbial Communities over Time
Water Management Research
2013 Annual Report
1a.Objectives (from AD-416):
1) Determine the recovery of microbial community structure after fumigation with time.
2) Examine the effect of fumigants on both target and non-target organisms in soil.
3) Compare these non-target organisms in fumigated vs. non-fumigated control sites.
1b.Approach (from AD-416):
Soil samples will be collected from different aged fumigated sites from calla lily field in Moss Landing, CA. Fumigated sites ranging in age approximately from few months to 30 years, will be selected. Non-fumigated fields will be used as a control. From each site, four transects will be identified and from each transect, soil samples will be collected from 4 different locations and 2 depths (0-5 cm and 5-15 cm). Phospholipid fatty acid (PLFA) analysis will be used to study the microbial community structure recovery for non-target organisms. Determination of Fusarium oxysporum and Pythium spp. populations will be done using dilution plating on Komada’s and P5ARP medium respectively.
This agreement supports Objective c “Determine soil microbial community structure following soil fumigation in fields soils with respect to time” of Objective 4 “Develop effective, practical, economical and environmentally acceptable approaches to replace methyl bromide as a pre-plant soil fumigant in ornamental and strawberry production systems” of the parent project. All equipment necessary for the phospholipid fatty acid (PLFA) analysis extraction was procured and Gas Chromatograph (GC) was installed in the laboratory and is functioning properly. Grower cooperators and sampling sites were identified. First set of samples ranging in age from 15 – 33 years after fumigation as well as non-fumigated soils with similar texture were collected from four growers in April-May 2013. Soil samples were collected for soil chemical analysis, soil aggregate analysis and PLFA analysis. Phospholipid fatty acid extraction of soil samples is in progress. Personnel have traveled to the MIDI Inc., for training of microbial identification system software.