Mr. Gobinath Sir you can get MBC, MBN by these formula
Microbial biomass carbon = (OCF - OCUF) / KEC
Where, OCF and OCUF are the organic carbon extracted from fumigated and unfumigated soil, respectively (expressed on oven dry basis), and KEC is the efficiency of extraction. A value of 0.25 is considered as a general KEC value for microbial extraction efficiency and used for calculation.
Microbial biomass nitrogen = (ONF - ONUF) / KEC
Where, ONF and ONUF are the organic nitrogen extracted from fumigated and unfumigated soil, respectively (expressed on oven dry basis), and KEC is the efficiency of extraction (0.45) as per Bremner and Kessel (1990).
Name: Soil microbial biomass carbon and nitrogen in forest ecosystems of Northeast China: a comparison between natural secondary forest and larch plantation, Indian Journal of Plant Ecology.Thank you....
Calculating microbial biomass carbon (MBC) and nitrogen (MBN) from fumigated and unfumigated titrated values is a common procedure in soil microbiology. Here is a step-by-step guide on how to perform these calculations:
Sample Preparation: Begin by preparing your soil samples, ensuring they are consistent in terms of moisture content and weight. You will need two sets of samples: one set that is chloroform-fumigated and another set that is unfumigated.
Extraction Process: Extract both fumigated and unfumigated samples using an appropriate solvent, typically potassium sulfate (K2SO4) for carbon and either K2SO4 or potassium chloride (KCl) for nitrogen.
Titrating Extracted Samples: Titrations are performed to determine the amount of carbon and nitrogen in the extracts. For carbon, you will use a dichromate oxidation method, while for nitrogen, a Kjeldahl distillation or similar method is typically used.
Calculation of Extractable Carbon and Nitrogen:Determine the concentration of carbon or nitrogen in both the fumigated and unfumigated extracts. This is usually given in mg C or N per liter of extract. Calculate the total amount of extractable carbon or nitrogen by multiplying the concentration by the volume of the extract.
Determining the Difference Between Fumigated and Unfumigated Samples: Subtract the amount of carbon or nitrogen in the unfumigated sample from the amount in the fumigated sample. This difference is used to estimate the microbial biomass carbon or nitrogen.
Applying Correction Factors:For MBC, use a correction factor (k_EC), commonly 0.45, to account for the incomplete extraction of microbial biomass carbon. For MBN, a correction factor (k_EN), which is often around 0.54, is used to account for the incomplete extraction and mineralization of microbial biomass nitrogen.
Final Calculation of Microbial Biomass:Calculate MBC as: MBC (mg C/kg soil) = (C_fumigated – C_unfumigated) / k_EC * soil weight. Calculate MBN as: MBN (mg N/kg soil) = (N_fumigated – N_unfumigated) / k_EN * soil weight.
Data Analysis: Analyze the calculated MBC and MBN values in the context of your experiment, considering factors like soil type, treatment conditions, and environmental factors.
Quality Control: Ensure to include quality control samples and replicates in your analysis for accurate and reliable results.
Interpretation of Results: Use these results to understand the microbial biomass and activity in your soil samples. Higher MBC and MBN values typically indicate a higher microbial biomass and potentially greater microbial activity.
Remember, the accuracy of these calculations heavily depends on meticulous sample preparation, precise titrations, and the correct application of correction factors. Additionally, it's important to stay updated with the latest methodologies and correction factors as these can vary based on recent research findings.
l Perhaps this protocol list can give us more information to help solve the problem.