microbial biomass in soil
DESCRIPTION
Microbial biomass in soil, measurement by chloroform fumigation incubation method, limits of measurement of microbial biomass, why microbes are important in the soil, why microbial biomass is important in the soilTRANSCRIPT
b.stev
Microbial Biomass in Soil
What is MICROBIAL BIOMASS?
SOIL BIOTA IS INFLUENCED BY:
HOW the land is used
Management techniques
CHANGE of the practises
this has effect to the microbial process
& their functions of survival in the soil
RESIDUE left after CROPSCROPS are harvested is nutrient
to soil &
facilitates the next crop
growth.
MICROBES
transform chemicals
aid pesticide degradation
participate in soil formation
contribute to soil aggregation
The limits of measurement:
o analytical cost involved
o ambiguous relationship to product
o benchmark values/ interpretation requires time to establish results
o cumbersome/ time needs
DEMAND HAS INCREASED:
can monitor soil quality
an environmental monitor
rapid/ improved techniques
gives the rates of turnover
ANALYSIS for clean food
HOW is this DONE?HOW is this DONE?Extraction of soil is done with a hollow rod to a depth of 10-15 cm
Samples are filtered to remove: stones/ roots/ finer fibres: size 2mm
Storage is at 4oC
SAMPLES are taken in squares at
appropriate spacings to ensure
all land variations are included;
it is quite an extensive process
20g soil are fumigated for a period of 24hrs with CHLOROFORM (CHCl3) in a humid dessicator
THEN: sample is inoculated with 0.5g fresh soil & placed in 1L airtight jars
incubated 10 days at room temperature
Controls - 20.5g samples are put in glass jars at time of fumigation are put to incubation : 10 days
method: chloroform fumigation, incubation
analyses the concentrations: carbon & nitrogen
CO2 produced in the headspace above the incubated samples is determined
by:
GAS CHROMATOGRAPHY
Bc = ( Fc / Kc)
CALCULATION performed from the results:
Kc = 0.41 factor
Bc = biomass of controls
Fc = fumigated samples
DATA is kept in graph/ & numerical value
Field/ SAMPLE sites, mapped for reference
Manufacturer, “HeinemeyerHeinemeyer”- ”- produced an instrumentthat determines microbial biomass by INFRARED ANALYSER
Soil pH - potentiometric 0.01M CaCl2 suspension
H2O content: samples - oven dried 105oC 24hr
CNS-2000 analysis uses dry combustion to measure both the carbon & nitrogen content
SOME OTHER METHODS & analysis to perform
ARE:
Bibliography
Archbold Biological Station. (2008). Soil microbial biomass. Retrieved September 26, 2008, from http://www.archbold-station.org/abs /publicationPDF/Groffman,etal.-2004-Ecosystems.pdf.
Soil Quality Pty Ltd. (2007). Soil quality. Retrieved September 25, 2008, from http://www.soilquality.org.au/factsheets/microbial-biomass
Rothamsted Research. (2004). Method download - soil microbial biomass group - rothamsted. Retrieved September 26, 2008, from http://www.rothamsted. ac.uk/aen/smbweb1/methods.php?id=903