Dear Dr. Suneel Kumar

Extracting organic matter from soil typically involves chemical or physical methods that separate the organic material from the mineral components of the soil. Here are some common techniques for extracting organic matter from soil:

Chemical Extraction:

· Sodium Hypochlorite (NaOCl) Digestion: This method involves treating the soil with a solution of sodium hypochlorite to break down the organic matter. The remaining residue is the mineral component.

· Potassium Dichromate (K2Cr2O7) Digestion: K2Cr2O7 is used to oxidize the organic matter in the soil, leaving behind the mineral content. The non-oxidized organic matter can be quantified as loss on ignition (LOI).

· Walkley-Black Method: A commonly used method for soil organic carbon estimation involves the oxidation of organic matter by K2Cr2O7 and titration to determine the concentration of organic carbon.

Physical Separation:

· Dense Fractionation: This method separates soil particles based on their density. Organic matter, which is lighter, can be separated from mineral particles.

· Sieving: Sieving can be used to separate coarse organic material (e.g., plant residues) from the fine mineral soil particles.

· Air-Drying and Wet-Sieving: This technique involves air-drying the soil to remove water-soluble organic compounds and sieving to separate larger organic matter from the soil.

Solvent Extraction:

· Certain solvents, such as chloroform or dichloromethane, can be used to selectively dissolve organic matter, leaving behind mineral components. This method is suitable for the extraction of dissolved organic carbon (DOC) or extractable organic matter.

Loss-on-Ignition (LOI):

· LOI is a simple method that involves heating a soil sample to a high temperature (typically 450-550°C) to combust the organic matter. The difference in weight before and after ignition represents the organic matter content.

· When conducting organic matter extraction from soil, it's essential to follow standard laboratory protocols and use appropriate safety precautions. Additionally, the choice of method may depend on the specific objectives of the analysis and the characteristics of the soil being studied.

As for books, here are some recommended texts that cover soil science and organic matter extraction:

· "Soil Microbiology, Ecology, and Biochemistry" by Eldor A. Paul: This comprehensive book covers various aspects of soil science, including organic matter and its dynamics.

· "Methods of Soil Analysis. Part 2: Microbiological and Biochemical Properties" (Soil Science Society of America): This part of the well-known "Methods of Soil Analysis" series provides detailed methods for analysing soil organic matter and its biochemical properties.

· "Soil Analysis Handbook of Reference Methods" edited by J. Robert M. Taylor: This book includes chapters on soil organic matter analysis and various extraction methods.

· "Standard Methods for the Examination of Water and Wastewater": While primarily focused on water and wastewater analysis, this book includes methods for soil organic carbon and dissolved organic matter analysis.

These books offer valuable insights into soil analysis, including the extraction and quantification of organic matter, and they can serve as useful references for soil scientists and researchers.

Thanks Sir

Extracting organic matter from soil involves several steps to separate and concentrate the organic components. Here's a general procedure that can be followed:

1. Sample Preparation: Collect soil samples from the desired location and remove any visible roots, stones, or large debris. Air-dry the soil samples at room temperature to remove excess moisture.

2. Sieving: Pass the air-dried soil through a sieve with a mesh size of around 2 mm to remove any chunks or particles that may interfere with the extraction process.

3. Extraction Solution: Prepare an appropriate extraction solution to dissolve and extract the organic matter from the soil. Commonly used extraction solutions include water, sodium chloride (NaCl) solution, or a mixture of water and alcohol. The choice of extraction solution depends on the specific needs and objectives of your analysis.

4. Extraction Process: Combine the sieved soil with the extraction solution in a ratio of typically 1:10 (soil to extraction solution). Mix or shake the solution vigorously for a specific period, usually several hours or overnight, to facilitate the extraction of organic compounds from the soil matrix. Warm water or mild heating can enhance the extraction efficiency if desired.

5. Separation: After the extraction, separate the liquid phase (containing the extracted organic matter) from the solid phase (remaining soil particles). This can be done through filtration or centrifugation. Filtration using a filter paper or a fine mesh sieve can effectively separate the liquid and solid phases.

6. Concentration: Concentrate the extracted organic matter by evaporating the solvent in the liquid phase. This can be done using techniques like rotary evaporation, freeze-drying, or air-drying, depending on the nature and quantity of the extracted organic matter.

7. Storage: Store the concentrated organic matter in a suitable container, such as a glass vial or a plastic bag, in a cool and dry place to prevent further degradation until further analysis or use.

Those are both great answers. However they raise a question in my mind. What if you wanted to recover the organic material unchanged? The oxidations destroy it. The solvent methods may change it or selectively remove only part of it. The sieve method probably would not be quantitative as the organics could be stuck to some of the minerals. Is there a way to collect the organics in its original form in a reasonablly quantitative way ?

I agree with my colleaques especially the details answer dealing physicsl and chemical methods