Organic Matter - Science topic

@ Sanhita, it is cell free supernatant because the liquid obtained after removing cells from the culture. Actually, extracellular organic matter means the organic components released by cells into the environment. In the true sense the cell free extract contains all substances outside the cells including organic and inorganic compounds, while extracellular organic matter focuses only on the organic molecules produced by cells.

Clay-microbe interactions stabilize organic matter and mitigate greenhouse gas emissions by regulating microbial activity and influencing decomposition processes. They also enhance bioremediation by providing surfaces for pollutant adsorption and facilitating microbial degradation, contributing to environmental sustainability.

I can't provide the full chapters, but I can summarize the methodology for organic matter analysis in sludge.

The "Methods of Soil Analysis, Part 3: Chemical Methods" (SSSA, 1996) includes several techniques for organic carbon determination. The most relevant for sludge analysis are:

✅ Walkley-Black Method (Wet Oxidation)

✅ Loss on Ignition (LOI) Method

✅ Dry Combustion (Elemental Analyzer, CHN Method)

MethodBest ForLimitationsWalkley-BlackModerate organic carbon, rapid analysisMay underestimate OC (~10–20% loss)Loss on Ignition (LOI)Quick estimation, low-costMay overestimate OM (loss of carbonates, structural water)Dry Combustion (CHN)High accuracy, precise TOC measurementExpensive, requires specialized equipment

Natural organic matter (NOM) can be effectively removed from surface water using methods such as coagulation with coagulants like poly aluminum chloride, adsorption with activated carbon, and advanced oxidation processes. Combining these techniques, such as integrating coagulation with ozonation, can enhance removal efficiency and improve overall water quality.

The combustion method may be approximate but ay least it does not involve the release of Cr into the environment

I might help you if you provide the details. You can message to me.

Nand Ram I agree to your point of view but however Qasim Ali has answered in a little brief way

Biodegradable/Biotransformation into sludge biosorption and carbon adsorption. Time different for changing.

Gábor Z. Szelényi yes would love to explain this and there are quite a few observations which I can list them here and few of them which came to my knowledge are : The environmental impact of an organic manure unit (such as a biogas plant or anaerobic digester) can vary depending on several factors, including: These are listed below:

1. Type of feedstock (e.g., food waste, agricultural waste, sewage sludge)

2. Scale of operation

3. Technology and design

4. Management and operation practices

Here are some potential environmental impacts of organic manure units:

Positive impacts:

1. Renewable energy production (biogas)

2. Reduced greenhouse gas emissions (by capturing methane)

3. Nutrient-rich fertilizer production (digestate)

4. Waste reduction and management

Negative impacts:

1. Odor and noise emissions

2. Pathogen and microplastic contamination (if not properly managed)

3. Water pollution (if effluents are not properly treated)

4. Land use and habitat disruption (if large areas are used for feedstock production)

Differences between mesophilic and thermophilic digestion:

1. Temperature: Mesophilic (30-38°C) vs. Thermophilic (50-55°C)

2. Microbial communities: Different species dominate at different temperatures

3. Pathogen destruction: Thermophilic digestion is more effective at killing pathogens

4. Biogas production: Thermophilic digestion can produce more biogas, but may require more energy input

Differences between small-scale and large-scale units:

1. Energy balance: Small-scale units may not generate enough energy to power themselves

2. Cost-effectiveness: Large-scale units can benefit from economies of scale

3. Management complexity: Large-scale units require more sophisticated management systems

4. Environmental impact: Large-scale units can have a larger environmental footprint

It's important to consider these factors when designing and operating organic manure units to minimize negative impacts and maximize benefits.

I rather wonder why you want to calculate OM from OC. OC can be measured precisely using elemental analyzers. Any factor is an empirical one, including the so-called "van Bemmelen factor" (1.724), which is wrongly named after him, as already Emil Wolff introduced the factor. You might check

If you already have OC data determined with an elemental analyzer, what is the benefit to convert these data into imprecise OM data?

Calculating soil carbon stocks using soil texture involves estimating the amount of organic carbon present in the soil based on its texture classification. Soil texture refers to the relative proportions of sand, silt, and clay particles in the soil, which influence its physical properties and carbon storage capacity. Here's a simplified method to estimate soil carbon stocks based on soil texture:

1. Determine Soil Texture: Use standard methods such as the USDA soil texture triangle or laboratory analysis to classify the soil as sandy, loamy, or clayey based on the percentage of sand, silt, and clay particles.

2. Assign Carbon Content Values: Different soil textures have different inherent organic carbon contents. Assign typical organic carbon content values to each soil texture class:

- Sandy soil: 0.5% to 1.5% organic carbon

- Loamy soil: 1.5% to 3.0% organic carbon

- Clayey soil: 3.0% to 6.0% organic carbon

These values represent general ranges and may vary depending on factors such as climate, vegetation, and soil management practices.

3. Calculate Soil Carbon Stocks: Once you have determined the soil texture and its corresponding organic carbon content range, calculate the soil carbon stocks per unit area (e.g., per hectare or acre) using the following formula:

Soil Carbon Stocks = Organic Carbon Content (%) × Soil Bulk Density (g/cm³) × Soil Depth (cm)

- Organic Carbon Content (%): Use the average value within the range assigned to the soil texture class.

- Soil Bulk Density (g/cm³): Measure or estimate the bulk density of the soil. This parameter accounts for the volume of soil occupied by solids and pore spaces.

- Soil Depth (cm): Determine the depth of the soil layer for which you are estimating carbon stocks.

4. Interpretation and Validation: Compare the calculated soil carbon stocks with empirical data or estimates from soil carbon measurement studies in similar soil types and environmental conditions to validate the results.

It's important to note that this method provides a rough estimate of soil carbon stocks based on soil texture and assumes uniformity within each texture class. Actual soil carbon stocks can vary within a soil type due to factors such as land use, management practices, and landscape heterogeneity. For more accurate assessments, consider integrating soil carbon measurements, remote sensing data, and modeling approaches. Additionally, consult with soil scientists or researchers for guidance on specific soil carbon estimation methods tailored to your study area and objectives.

Thanks Uddhav

There are well-documented 'anaerobic' sites in nature in the sense of very low oxygen. Does that mean a complete absence of O2 ?

The Yasso model divides carbon into different soil organic carbon (SOC) pools, including an acid-soluble fraction1. Here are some methods for determining the soluble chemical fractions of soils and organic matter:

Creating SOC Gradient: The best way to create a SOC gradient is to mix externally applied organic matter into the soil1. This can be done by adding different amounts of organic matter to different sections or layers of the soil. The organic matter will decompose over time, contributing to the SOC content.

Dear Suneel Ji,

Yes, the amount of nitrogen in organic matter can be determined using the Kjeldahl method. The Kjeldahl method is a widely used technique for the determination of nitrogen content in organic and inorganic substances, especially in organic matter such as soil, plant material, and food.

Digestion: The organic material is digested with concentrated sulfuric acid. During this process, nitrogen present in the organic matter is converted into ammonium sulfate.

Distillation: The ammonium sulfate formed in the digestion step is then distilled with a strong base (usually sodium hydroxide). This results in the release of ammonia gas.

Titration: The liberated ammonia gas is captured in a known volume of standard acid solution. The excess acid is then titrated with a standard base solution to determine the amount of acid consumed. This information is used to calculate the nitrogen content in the original sample.

Nitrogen %=(Volume of acid used in titration×Normality of acid×Equivalent weight of nitrogenWeight of the sample)×100Nitrogen %=(Weight of the sampleVolume of acid used in titration×Normality of acid×Equivalent weight of nitrogen​)×100

The equivalent weight of nitrogen is 14 (since nitrogen is diatomic, with a molecular weight of 28 g/mol, and the Kjeldahl method measures N, not N2).

I agree, but you are letting out the bad aspects of fungi on crops production.

Using 10% KOH for digestion of fecal matter is achievable. KOH volume can be 5 times of the organic matter to be digested. This can be incubated for 48-72 hrs or till the organic matter fully digests.

You can follow the procedure of

The best way to determine soil bulk density is to actually measure it in the field. Bulk density is soil mass divided by volume on an oven dry basis. Organic matter is a small fraction of the total mass in mineral soils. When a soil sample is collected in the field and brought into the laboratory, the actual bulk density is destroyed resulting in "lab dirt".

Organic matter does influence soil aggregation which influences soil bulk density and other properties. But in collection of the sample without a measurement of in situ volume at the time of collection makes it extremely difficult to estimate the bulk density later with any accuracy.

@ Suneel, in India under humid and sub-humid region we have high temperature and heavy rainfall that resulted rapid decay of organic matter. Similarly, under arid and semi-arid region due to high temperature and slow weathering of rocks we have less organic matter in the soil. It is very difficult to build soil organic matter rapidly. You may add continuously plant residues, compost, FYM, reduce drainage or cultivation to slowly build organic matter in the soil.

To start off the soil has physical chemical and biological components within it.

Aggregates refer to the physical separation of particle sizes based on laboratory sieving analysis these are separated by the size of the particles.

These fractions by size are dried and weighed and when exposed to water washing the reduction in their dry weight is a measure of stability. The more of the fraction lost the less the stability of the fraction.

Aggregates are formed by a process of physical chemical and biological nature. Roots microbes decomposers and the nature of the chemistry of the soil itself are very important.

A sandy soil will not aggregate well and has a major issues of favorable aeration but poor retention ability.

The ability of the soil to aggregate well is dependent on fine particles silt and clay calcium or iron or aluminum can be important and organic matter.

Floculation of clay and dissolved organic matter depends on multiple cationic bridges such as calcium, iron or aluminum. The majority of the best soils globally derive from limestone parent material.

To stablize particles such as suspended clay or organic matter the role of calcium is essential in my mind.

So the presence of large aggregates is very much indicative of a soil with good tilth and high productivity as it favors both aeration and water retention.

Ideally the soil will have one quarter to one half fine material which is either clay or silt the calcium in soil test of 1,000 and the presence of 4 to 5percent soil organic matter best soil pH 6 to 7.2

It is observed that wheat rice system does not have optimum soil properties. One issue is the way rice practice leads to issues with physical structure of the soil.

In North America maize culture does reduce soil quality and the structure of the soil is very much enhanced by soybean in rotation.

Under the rice and wheat system the prescription to improve soil structure and productivity is enhancing the use of legumes in rotation.

The use of broad bean as a winter annual could be combined previous to rice or wheat it would eliminate the nitrogen need for rice or wheat and improve the yield and help control weeds and diseases of the grains.

After wheat a summer legume might be possible like sun hemp which also is excellent for soil regeneration.

Besides legumes I would like to mention the Mexican Sunflower produces a wonderful opening of improved potassium availability and a wonderful rotation effect and experimenting with sunflower would be well worth your while.

My hypothesis here is wheat rice rotation does not optimize soil condition.

The use of increased legumes will not only improve soil condition and increase but wheat and rice yields and quality but also lower the cost of production.

Suggest adaptive research in this area to improve the soil condition and the profitably and to improve the environment and climate effect.

A rotation more centered on legumes will remove the need for ammoniated nitrogen fertilization and the untoward effect it has on soil condition. .

Yes, both LandGEM and IPCC (Intergovernmental Panel on Climate Change) provide methods to calculate emission factors for landfilling waste.

Using LandGEM, you can input specific data related to your landfill, such as waste type, landfill size, waste deposition rates, waste age, and climate conditions. The model then uses this data to estimate methane generation potential and CO2 emissions from the landfill.

The IPCC guidelines use a Tiered Approach, where different tiers represent varying levels of data availability and accuracy. The emission factors calculated through these tiers are categorized into Tier 1 (default values) and Tier 2 (country-specific data). Tier 1 values are generally less accurate, while Tier 2 values are based on site-specific data and are considered more reliable.

Countries or regions that have collected sufficient data may use Tier 2 emission factors, which are tailored to their specific waste characteristics and landfill conditions.

In summary, both LandGEM and IPCC provide methods to estimate emission factors for landfilling waste. LandGEM is a software tool developed by the U.S. EPA, while the IPCC guidelines offer a standardized approach for greenhouse gas inventories, including landfill methane emissions, which can be adopted by countries or regions worldwide. The choice of which method to use depends on the data availability, level of accuracy required, and the specific needs of the waste management project or greenhouse gas inventory assessment.

No till has been assessed in a meta analysis by Puget and Lal 2005

Soil organic carbon and nitrogen in a Mollisol in central Ohio as affected by tillage and land use

Author links open overlay panelP. Puget, R. Lal

https://doi.org/10.1016/j.still.2004.03.018Get rights and content

Abstract

Minimum tillage practices are known for increasing soil organic carbon (SOC). However, not all environmental situations may manifest this potential change. The SOC and N stocks were assessed on a Mollisol in central Ohio in an 8-year-old tillage experiment as well as under two relatively undisturbed land uses; a secondary forest and a pasture on the same soil type. Cropped systems had 51±4 (equiv. mass) Mg ha−1 lower SOC and lower 3.5±0.3 (equiv. mass) Mg ha−1 N in the top 30 cm soil layer than under forest. Being a secondary forest, the loss in SOC and N stocks by cultivation may have been even more than these reported herein. No differences among systems were detected below this depth. The SOC stock in the pasture treatment was 29±3 Mg ha−1 greater in the top 10 cm layer than in cultivated soils, but was similar to those under forest and no-till (NT). Among tillage practices (plow, chisel and NT) only the 0–5 cm soil layer under NT exhibited higher SOC and N concentrations. An analysis of the literature of NT effect on SOC stocks, using meta-analysis, suggested that NT would have an overall positive effect on SOC sequestration rate but with a greater variability of what was previously reported. The average sequestration rate of NT was 330 kg SOC ha−1 year−1 with a 95% confidence interval ranging from 47 to 620 kg SOC ha−1 year−1. There was no effect of soil texture or crop rotation on the SOC sequestration rate that could explain this variability. The conversion factor for SOC stock changes from plow to NT was equal to 1.04. This suggests that the complex mechanisms and pathways of SOC accrual warrant a cautious approach when generalizing the beneficial changes of NT on SOC stocks.

Commentary is that no tillage can be used to increase carbon sequestration as increased organic matter in the soil.

The use of cover cropping rotation and compost or manure amendment can also be used alone and togetjher for the same purpose.

Much greater effect can be found with a suite of carbon positive practices are used in systematic practices. Mixed animal and crop farming are particularly powerful of that purpose.

In Visual MINTEQ, the user can select from two organic complexation models, NICA-Donnan and SHM, to calculate the extent of metal-DOM complexation. These models cannot be used in GWB, for the following reasons:

1. Correct usage of these models in GWB would require additional coding in the GWB source code itself, and as far as I am aware no efforts to add these models into the code have as yet been made

2. In addition, the thermo_minteq database in GWB does not contain the metal-DOM complexation reactions, which are stored in separate databases and not available in the GWB format. But even if those were available, you would still not be able to generate correct results, due to reason no. 1 above!

Would someone please help? I have carried out Fenton pretreatment and that has left out a lot of ferric precipitates on my filter paper. So, i have added 50 to 60 % of sulphuric acid onto my GF filters to dissolve the ferric precipitates. Then, I could see that the precipitates were dissolved immediately and then I have washed the filter paper with plenty of millipore water. But, I would like to know whether this process (less than one min of contact between filter paper and 55 % sulphuric acid solution) would affect the chemical nature of my microplastics? Observation in microscope suggests that discolouration has occurred. But I would like to know does any of you has encountered similar situation? What is your recommendation? Thank you so much.

Depending on the pH buffering capacity of the soil, the inputs may not be sufficient to change the pH but they may decrease Al toxicity in the short term. and this could benefit the growth of acid-sensitive plant species. If it's a research study you could measure some interesting things, such as reactive Al species in the soil and the uptake of P and some other elements by plants.

Follow P.K. Behera sir for this

The disappearance of dry matter gives a good estimation of the respiration loss.

There is no complete solution to this problem. You can use detergents, ultrasound, vortexing with beads, etc. to release attached cells. The stronger the dispersion power, the more release. But at a certain point, some cells will start to loos viability, while other cells remaining attached. My advise is to think about the practical or theoretical objective of research: do you really need for some important reason to release ALL cells? Or do you have another more substantial objective? In the first option, just find such an aquatic ecosystem that does not have a high binding capacity to microorganisms (e.g. With sand bottom). In the second option, there are many ways how to characterize a community without 100% release of cells

Multiple wavelength measurements may also help

Addition of crop residues I. e rice straw, maize straw as source of available carbon. Rice straw supports fungal growth that can accelerate the organic matter decomposition. Applications of green waste compost, sedge peat, furfural residues, farm yard manure, cattle manure, poultry manure, different agro-industrial by products, composts, cow manure and rice husk. Poultry manure can increase CEC and soluble and exchangeable K, which is a competitor of Na. Please go through the following review article, Effectiveness of organic wastes as fertilizer and amendments in salt affected soils. Agriculture, 2015:5(2), 221-230

The best venue for biochar is acid infertile soils with soil compaction issues.

The biochar acts as a type of liming agent in those soils addressing acidity and providing essential micronutrients.

Biochar and compost are complementary the larger effect is from compost.

If you put on 15 MT per hectare of good compost and 5 MT of biochar you can renew and invigorate many acid infertile ultisols and oxisols many found in tropical environments.

Rates above those rates get into diminished and negative reactions and are not very economical.

Work on minimum doses with optimum economics are recommended

Soil organic matter can affect the soil physical condition or physical health and the chemical condition or health and the biological condition or health.

The physical condition of the soil is made less dense from soil organic matter This soil organic takes compacted mineral material and the fluffy organic matter loosen it this can be measured by soil density.

The chemical condition is improved as soil organic matter improves the mineral contents.

Soil organic matter serves as food for diverse communities of animals such asn insects and earthworms and microbes like fungi and bacteria.

Most organisms in soil play neutral and positive roles and a small number are pathogens.

When overall diversity and populations of soil organisms are high the pathogenic component of soil is put into check.

minerals physical condition and biology are all important for productive soils the flluffy factor provides the water and air needed for robust crop production, the biology and air capacity of soils is related to organic matter content and organic matter is a basis of biological diversity and populations which is highly favorable.

Outside my field but the past Australian authority was J O Skjemstad and you may find his publications useful.

Dear @Ajoy Kumar Saha You can access the links given below; hope, these should be useful to you: