Soil Organic Matter - Science topic

عند حد معين يؤثر وبشكل إيجابي ولكن عند ارتفاع تركيز يغير درجة حموضة التربة نحو القاعدية وبذلك تتأثر بعض الأنواع من ميكروبات التربة At a certain level, it has a positive effect, but when the concentration increases, it changes the soil acidity towards alkalinity, thus affecting some types of soil microbes.

For purifying soil organic matter, specifically humic and fulvic acids, use dialysis membranes with a Molecular Weight Cut-Off (MWCO) of 1000 to 3500 Daltons. For humic acids, membranes with 3000-3500 Da MWCO are suitable, while for fulvic acids, use membranes with 1000-2000 Da MWCO. This range effectively removes smaller inorganic ions while retaining the larger organic compounds of interest, with the smaller pore size for fulvic acids accounting for their lower molecular weight compared to humic acids.

Himanshu Tiwari

Various techniques such as loss-on-ignition, the Walkley-Black method, dry combustion, soil respiration, near-infrared spectroscopy, and soil health assessments are utilized to classify and measure soil organic matter (SOM) content, providing insights into soil health and fertility. These methods enable farmers to tailor soil management practices such as cover cropping, reduced tillage, crop rotation, and organic amendments to increase SOM levels and improve soil fertility, structure, and water retention. Monitoring SOM content helps optimize nutrient availability, balance soil biological activity, and enhance soil structure and water retention, ultimately promoting better root growth, nutrient uptake, and drought resilience in crops, leading to increased productivity and sustainable land stewardship.

The different carbon fractions of the soil amended with fresh residues showed significantly higher mineralized rates than with same quantity of compost because the higher amounts of humic substances and fulvic and humic acids that serves to support plant life.

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.

Physically, it plays a crucial role in enhancing the physical properties of soil. By improving soil structure, it effectively mitigates soil erosion and facilitates better water infiltration and retention. Consequently, this creates an optimal environment for plant roots and soil organisms to thrive.

Chemically, soil organic matter exerts a significant influence on the chemical aspects of soil. It directly impacts the cation exchange capacity, which refers to the soil's ability to retain and release essential nutrients for plants. Additionally, it also enhances the soil's capacity to buffer changes in pH, ensuring a stable and conducive environment for plant growth.

Biologically, soil organic matter assumes a vital role in the biological realm. It serves as a valuable source of nutrients and energy for microbial biomass and higher plants. This symbiotic relationship between soil organic matter and these organisms fosters a healthy and flourishing ecosystem.

In conclusion, the advantages of soil organic matter encompass its ability to improve soil structure, control erosion, enhance water infiltration and retention, influence nutrient availability, and provide nourishment for microbial and plant life. By recognizing and harnessing these benefits, we can cultivate sustainable and productive agricultural practices while preserving the health of our soils.

Over tilling can be an enemy to optimized maize production. While no tillage is more favorable to soil organic matter content it also constitutes issues with the use of herbicides genetically modification issues and costs involved.

One of the best ways to increase soil organic matter and lower inputs is the maize legume relation. Soybean in rotation will lower the need for supplemental nitrogen reducing cost and improving soil quality and it also feeds valuable earthworm populations.

A way of increasing the tilth of soils is to create system of raised beds and allowing mechanization but restricting traffic zones.

For the overall soil health and organic matter the return of crop residues in the form of organic matter amendment is extremely important. For small holders the use of mixed plant and animal farming is a way to increase the income generation.

Milk animals give valuable which can support the generation of methane gas for homestead energetic needs and the compost remains for field applications which feed the soil increase organic matter and increase the crop nutrient content.

Farmers can target soil rather than look to brought agrichemical inputs but more educational input is needed for these regenerative agriculture approaches.

Dear, Dr, Himanshu Tiwari

What the historical trend of agricultural soils in the world taught us, soil without organic matter and organic carbon cannot be productive for us in the field of agricultural production. Because agricultural soils show synergy with natural components and make stability possible in the rhizosphere environment. In this regard, pay attention to the following two important articles.

Conventional agriculture causes increased greenhouse gas emissions, soil erosion, water pollution, and threatens human health. Organic farming has a smaller carbon footprint, conserves and builds soil health, replenishes natural ecosystems for cleaner water and air, all without toxic pesticide residues. While organic farming tends to enhance soil health and conventional practices degrade it, relying on tillage for weed control on both organic and conventional farms degrades soil organic matter and can disrupt soil life in ways that reduce crop mineral uptake and phytochemical production. Soil organic matter significantly improves the soil's capacity to store and supply essential nutrients (such as nitrogen, phosphorus, potassium, calcium and magnesium), and to retain toxic elements. It allows the soil to cope with changes in soil acidity, and helps soil minerals to decompose faster.

, J. C. Tarafdar ,

thank you both very much for your well thought out answers! I apologize for answering so late, other activities kept me busy and now I return to the topic. So again, thank you very much!

Thank you Qasim Qayyum Kashif, that's very interesting. I appreciate the time you're spending to help with this.

It is best to store soils air-dry. While air-drying, which can be done at room temperature, you should spread the soil as much as you can to create a vast surface. You should use an oven with circulating air. If you're looking for specific organic soil matter components, the temperature shouldn't rise above 35°C.

It is suggested to carry out soil drying by air. Drying at 50°C is stronger and may affect, for example, some labile organic compound.

You are right in that soils vary in their capacity to accumulate soil organic matter.

The amount of capacity can be a function of clay content and the amount of calcium.

When clay and organic matter become complexed through the agency of cationic bridging the decay of soil organic is greatly reduced and this favors soil organic matter accumulation.

In a very sandy soil the adding of silt and clay will result in better soil organc matter conservation and increase.

In the acid soils the liming will improve the ability of soil to retain can conserve soil organic matter.

Soil calcium is need for the earth worm activity with are prime buider so soil organic matters.

A well wormed soil has excretion of calcium precipitates.Vermicompost is characterized by high content of calcium and phosphorus and serves as an excellent organic starter amendment giving both a complete nutrient resource but also humic materials which stimulate germination and seedling response particularly root development.

No-tillage had higher amounts of N mineralization than conventional tillage. Over time, non-tillage methods provide a significant contribution to the overall nitrogen concentration of the topsoil.

Oxidation and microbial proliferation leads to SOM loss. So as long as it is safe from oxidation and microbes there will be no loss of SOM. But still if tillage is done in soil and exposure of surface soil to sunlight is happen then it will take very less time for SOM to loss.

we have worked on this point in the following manuscript:

Plant residues/litter, concentrated oil cakes, poultry manures, night soil, bone and blood meal, animals dung and urine, all these when we add it in large quantity releases acids during their decomposition

Please find the attachments.

Regards.

This is a good question.

This is a good question.

Also check http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/34/047/34047660.pdf?r=1

You might want to look at https://en.wikipedia.org/wiki/Bland%E2%80%93Altman_plot

which was specifically designed to look at agreement between two measures. This paper well explains the method:

It is one of the most highly cited papers of all time.

CV is dependent on errors committed during measurements. If errors are less CV should be acceptable. So for your case to reduce the high CV may be analyze the samples again and get new values and observe there will be a variation to the previous ones.

Yes it's true because organic matter contents increase microbial population so that's why it takes part in mineral uptaken by plants

Nice question . so far i am not aware ...if there is any and anyone knows , please share your experience ...

As soil organic matter is derived mainly from plant residues, it contains all of the essential plant nutrients. The content of soil organic matter varies according to the type of the soil. The soil organic matter content in soils is given as a result of determination of soil organic carbon (Corg.), On average it forms 58% of its composition.

In fact, the two types of the energy accumulated in the soil organic matter are equivalent. This energy can be perceived as:

1. Energy of the accumulated organic material forming the soil organic matter,

2. Metabolic energy, which drives the biological processes and originating from the organic material decomposed in the soil.

in the solar energy and the process of photosynthesis, and the energy accumulated in the organic matter forms a resource comprising nutrients and energy needed for the functions of the soil organisms.

In the humus layer of the forested areas, it is equal to 5.04 kcal/gram, , whereas in marshy soils – 4.87 kcal/gram.

For the purpose of determination of the energy value of SOM, it was assumed that the content of the organic matter is equal to 4.7 kcal/gra, This was coupled with determination of its energy potential. The resource of the organic matter will establish for the soil depth profile of 0-30 cm, together with the energy value expressed in MJ/ha , and the theoretical energy potential expressed as an equivalent of thermal fuel.

regards

check this out.

Place about 10 g air dry soil containing no particles larger than 2 mm in a polythene bottle. Add 50 ml of NaOAc solution (pH 5-6), warm on water bath. Then centrifuge and decant the supernatant. After removal of excess salts and CaCO3, follow the treatment of H2O2 for removal of organic matter. Add 5 ml of H2O2 in a sample previously treated to remove soluble salts and carbonates. Add H2O2 in increments of 5 to 10 ml or less, stir the suspension, and allow time for any strong effervescence or frothing to subside. Place it on a water bath to warm. Remove the centrifuge bottle from the water bath and allow it to cool. The reaction of soil with H2O2 is essentially complete when the soil sample loses its dark colour or when conspicuous effervescence ceases. Some effervescence will always be present due to the decomposition of the H2O2. Centrifuge the bottles and decant the supernatant. The sample is now ready for the next step.

Peat contains a very high amount of humus. According to the famous soil science book by Scheffer and Schachtschabel (2016), humus can store about 3-5 times its own weight in water.

Soil organic carbon (SOC) is an important and widely used soil biological parameter. Organic matter is ordinarily and incorrectly used to portray the same soil fraction as total organic carbon. But the fact is that soil organic matter is different from total organic carbon, because soil organic matter includes all the elements H, N, O, etc. which are also part of organic compounds, not only carbon.

To differentiate you need isotopic labelling, probably with multiple isotopes

Dear Xingde Xu, please have look into a review published by Prof. Wulf Amelung and his colleagues a couple of years ago:

Best regards

Nils

Dear Manish.

Let me know, would you like to know: "Why microbial community 'diversity' (instead 'structure') didn't increase with soil organic matter?"

To answer your question is necessary to think about two aspects: the organic matter quantity and quality. I mean, you need to know the nutrient pools of the OM and the number of different carbon sources present in your OM (i.e, the C sources diversity). This will be very important.

For example, you can increase SOM using a poor-nutrient material (high C/N relation, like sugarcane or eucalypt residues). Doing this, you not necessarily will affect positively the microbial community, because you added a high quantity of a specific C source in the soil. O the other hand, you can put a nutrient-rich material (low C/N relation, like soybean residues) and increase the microbial abundance exponentially, but not necessarily increase the microbial diversity. In the two cases, you will favor specific microbial groups only.

However, if you added different plant materials, or, naturally, different C sources derivated from the plant through root exudation, the possibility to increase both abundance and number of microbial groups is higher than above-mentioned practices.

Regards.

If crop residues returned to the soil over 30 years have been consistent in quantity or type, then the C content of the soil would not likely change. The reason for this is that the soil C is in equilibrium with the biomass C inputs and the environmental conditions of the soil (temperature, moisture, nutrient inputs, etc.). Adding manure is essentially an importation of C which changes the equilibrium between the C sources and soil. Because the manure is of different quality, the equilibrium has to adjust to the manure source, nutrient load and other manure characteristics. If different rates of manure are applied, each manure rate would require a different set of equilibrium conditions. However, if the manure applications are consistent and of similar quantity and quality, over time you should see SOC attain a new level that will remain relatively constant until a new equilibrium is reached.

The key to changing the SOC levels in soil (both in a positive or negative direction) is to change equilibrium conditions (change residue/biomass inputs, temperature, moisture , season length, type of residue, nutrients, tillage, etc.). Changing any of these will generate equilibrium changes that will result in increase or decrease in SOC over time.

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Organic matter of the soil is associated with the climatic factor and the microbiological sphere of the soil. And also contacted with chemical absorption of the soil.

OM decomposition is mainly microbe mediated process and is affected by soil temp., moisture, O2 and N2 content and quality and quantity of available carbon substrate and soil management practices. Soil organic carbon consists of various heterogeneous pools which differ in their stability and availability and are characterized by their turnover rates. Older, more recalcitrant C pools are less decomposable by microorganisms, in comparison to younger C pool. According to their turnover time various C pools contribute differently to soil CO2 as the major product of microbial decomposition. Thus, all the OM is not converted to CO2.

The terrestrial carbon cycle maintains a balance between photosynthesis and respiration. Carbon from the atmosphere is transferred to soil via ‘carbon fixing’ autotrophic organisms, (mainly photosynthesizing plants and photo and chemoautotrophic microbes) that synthesize atmospheric carbon dioxide into organic material. Fixed carbon is then returned to the atmosphere by a variety of different pathways that account for the respiration of both autotrophic and heterotrophic organisms. The reverse route includes decomposition of organic material by ‘organic carbon-consuming’ heterotrophic microorganisms that utilize the carbon of either plant, animal or microbial origin as a substrate for metabolism, retaining a part of carbon in their biomass and releasing the rest as metabolites or as CO2 back to the atmosphere. Plants benefit from root exudates mainly via improved acquisition of soil nutrients mobilized by microorganisms.

PAHs in soil can be transformed through photo-chemical reactions, giving rise to diols, phenols and aldehydes as well as epoxides. Transformation of PAHs in soil can occur only down to a soil depth of 1 mm. Higher soil temperature favours photo-degradation of so- called light PAHs and formation of toxic metabolites of "heavy" PAHs in soil. For more details consult https://www.ncbi.nlm.nih.gov or Environ.Monit,Assess.2018;190(7):422

The % of sand, silt and clay in the soil established the nature or texture of soil. Hence, first we have to determine the % of these components of soil.

Organic matter is important for soil health and crop productivity and soil quality.

Temperature, rainfall got definite relationship with vegetation and soil organic matter and soil organic carbon. These are long established phenomenon.

Dear Marlon

Andisol with a high content of humic compounds, the majority of the proportion of Al-amorphous will be complexed to Al-humic, so it makes sense that in Andisol with high organic content, Al-humic> Al-amorphous. Conversely, at andisol with low OM content, only a small portion of Al-amorphous complexed to Al-humic so that Alo> Alp content

Dear Thomas,

I strongly suggest not to convert. Indeed soil organic carbon concentration typically decreases with increasing soil depths, but the degree varies strongly between soil types. Thus, it does not excist a general rule or equation that you can apply. However, converting carbon concentrations into carbon stocks (stock=carbon concentration*thickness of soil layer/horizon*soil density) works well and is widely accepted in soil science.

In case soil density (or bulk density) has not been reported you can apply a pedo-transfer function introduced by Post & Kwon 2000 (doi: 10.1046/j.1365-2486.2000.00308.x ). Land use change may have an impact soil mass, which you can address by applying an approach introduced by Ellert & Bettany 1995 (doi: 10.4141/cjss95-075 ).

BR Nils

Each approach has its advantages and dis advantages. I think your question can be a topic for aresearch project or a postgraduate thesis. It will make a weighting scale for both approaches and provide the best for the researchers according to their local environment.

The changes in oxidative or active organic matter will correlate with long term changes.

The work of Lal and his students suggested that no till on the global tilled lands would counteract about 10% of the global carbon emissions.

Raw manure use and no till in a maize monocutture both have similar carbon sequestration if the effects are additive it would suggest 20% of the current global emissions could by counteracted by using raw manure and no till in a maize type monoculture.

Cover crops which are 2 to 4 times the effect of raw manure could up that fiewure to 60%.

Compost usage can lead to potential to completely counteract the current global carbon emissions.

Terra preta demonstrates that one hectare with less than 7,000 kg per ha carbon as in infertile Amazonian oxisol can be stabilized at over 300,000 kg per ha carbon representing a 1,000,000 kg per hg of carbon dioxide.

While it unlikely that a changed energy system alone can counteract global warming from elevated greenhouse the role of sequestration along with transtition to renewable energy economy does pencil out as a viable way to address long term global warming concerns.

Have you look into the FAO database: http://www.fao.org/statistics/databases/en/

Some of the data might be there at a global scale.

I assume that the root:shoot ratio information will be quite difficult to obtain accurately.

Mohammed JARULLAH Farhan

Generally there are two ways to extract only a part of non extractable residue. Either through acidification of the extract or by means of an enzymatic reaction. Yet conjugates are very difficult to extract only to a minimal extent.

Maybe see thse two recent papers:

Thank you very much Larry.

Earthworms and snails can be excellent indicators of the health of soils but they are just 2 organisms which are part of a much larger diversity within soil biota. They are part of a much bigger soil food web where mites, collembola, symphilans, and many other micro invertebrates contribute with their ecologies and metabolisms to support life in-and-above ground. Agricultural practices such as: soil tillage and the application of agrichemicals reduce abundance and diversity of soil life, making agriculture even more dependent on the same practices I have mentioned above and thus reducing farming to an extractive activity. Fostering soil life and the health of the soil community enhances the sustainability of farming systems, making agriculture regenerative and restorative.

Dear Thomas Fungenzi

Have a look at these published papers about biochemical composition of cocoa leaves:

In my opinion an organic fertilizer is employed to "feed" the soil web rather than the agronomic crop. Therefore, an organic fertilizer banks and retains in the soil nutrients already in place and those added by soil biota and their metabolisms. If the C:N ratio is <20:1 and this ratio becomes optimal to foster abundance and diversity of the soil food web, then the objective of using an organic fertilizer has been achieved. Under these conditions, most of the soil physical, chemical and biological characteristics should become optimal to support a healthy and productive plant population if the agronomic practices include: soil conservation through cover cropping and rotations of various agronomic species.

Dilip Kumar Pal & Thanks Sir!

While nitrogen was not limiting oxygen was. Vertisols respond to raised bed culture the raised bed allows for more conclusive drainage aiding in aeration.

The raised bed used in the dry season can be supplemented with drip irrigation and row cover. The healthy start can make it possible to have better responses because susceptibility to anoxic environment is maximum in seedling stages and can become less later.

You will want to select crops and varieties that adapt well to vertisols.

Definitely removal of meat and milk may deplete soil but while grazing some nutrient input also adding through dung and urine that may also consider while calculating the exact deplete of soil nutrients.

Any enzyme measurement to monitor microbial activity is an 'indirect' method to monitor specific microbial activity (e.g. urease, denitrification enzyme activity (DEA) and dehydrogenase). Most extracellular enzymes (secreted outside the cells) are captured in soil colloids and can accumulate over time hence the amount of enzyme activity may not reflect the actual microbial activity or microbial counts.

On the above basis, measuring CO₂ may provide more accurate indication of the overall heterotrophic microbial activity in unsaturated soils.

In the case of compost, depending on the composting stage, CH₄ could also be emitted from the anaerobic process hence CO₂ may not provide the full picture. If composting process has been fully completed, CO₂ may be used as a sole indicator.

Hi dear Raghad Mouhamad

Can you give me your e-MAIL, I will sent you my spectrum.

Thank you!

Good morning Thank you for your question and your interest in our work. I am also a ph d student and other authors have more in-depth knowledge of mine. I advise you to evaluate the content of humic carbon: it provides qualitative as well as quantitative indications. You can find some articles on this subject. I hope that my contribution, even if modest, can help you

Dear Thomas Fungenzi,

Please have a look at these useful PDF attachments.

Good luck!

No I don't have

Please go through the following article for detailed information

Soil organic carbon as observed in lowland of continuous rice cropping in guinea savanna..... 2017. Journal of Research in Environmental and Earth Science 3(3):25-34.

Co-efficient of humus mineralization can be calculated by equation of Bouvier et al, 2016

K2= (0.3t - 3)/[(1+0.05 X CL (%)) X (100 + 0.15 CaCO3)(%o)

t = annual average temp, CL % is the proportion of clay in soil, CaCO3 is the soil content of CaCO3 (%), known that 40.04 % is the content of Ca

Qualitative and quantitative differences in SOC can affect the rate of humification.