Microbial Biomass in Soil


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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 soil

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Microbial Biomass in Soil

  1. 1. b.stev Microbial Biomass in Soil
  2. 2. What is MICROBIAL BIOMASS ?
  3. 3. 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
  4. 4. RESIDUE left after CROPS are harvested is nutrient to soil & facilitates the next crop growth .
  5. 5. <ul><li>MICROBES </li></ul><ul><li>transform chemicals </li></ul><ul><li>aid pesticide degradation </li></ul><ul><li>participate in soil formation </li></ul><ul><li>contribute to soil aggregation </li></ul>
  6. 6. <ul><li>The limits of measurement: </li></ul><ul><li>analytical cost involved </li></ul><ul><li>ambiguous relationship to product </li></ul><ul><li>benchmark values/ interpretation </li></ul><ul><li>requires time to establish results </li></ul><ul><li>cumbersome/ time needs </li></ul>
  7. 7. DEMAND HAS INCREASED: <ul><li>can monitor soil quality </li></ul><ul><li>an environmental monitor </li></ul><ul><li>rapid/ improved techniques </li></ul><ul><li>gives the rates of turnover </li></ul><ul><li>ANALYSIS for clean food </li></ul>
  8. 8. 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 4 o C SAMPLES are taken in squares at appropriate spacings to ensure all land variations are included; it is quite an extensive process
  9. 9. 20g soil are fumigated for a period of 24hrs with CHLOROFORM (CHCl 3 ) 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
  10. 10. CO 2 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
  11. 11. Manufacturer, “ Heinemeyer ”- produced an instrument that determines microbial biomass by INFRARED ANALYSER Soil pH - potentiometric 0.01M CaCl 2 suspension H 2 O content: samples - oven dried 105 o C 24hr CNS-2000 analysis uses dry combustion to measure both the carbon & nitrogen content SOME OTHER METHODS & analysis to perform ARE:
  12. 12. 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