In my own understanding of organic matter content, it enriches the soil with nutrients that boost the the soil overall performance.

Thank you

Olutosin

In my own understanding of organic matter content, it enriches the soil with nutrients that boost the the soil overall performance.

Thank you

Olutosin

Yes, I think it support to get better crop.

Yes. I do. I use organic fertilizers of kitchen waste for my yard plants. They produce better taste and massive fruits.

Dear Dr. Anoop Kumar Srivastava

Here are few links, hope you will find these links helpful.

Regards.     ---- Amit

http://iopscience.iop.org/article/10.1088/1748-9326/10/12/123004/pdf

https://www.scientificamerican.com/article/what-helps-organic-soils-store-more-carbon/

https://fjfsdata01prod.blob.core.windows.net/articles/files/261903/pubmed-zip/.versions/1/.package-entries/fevo-05-00096/fevo-05-00096.pdf?sv=2015-12-11&sr=b&sig=pVor8%2FpN5wadcNXFgKkTfX0DmkYTV4xHzac0acIwoY0%3D&se=2017-09-29T12%3A53%3A40Z&sp=r&rscd=attachment%3B%20filename%2A%3DUTF-8%27%27fevo-05-00096.pdf

http://edepot.wur.nl/28212

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4243251/pdf/ncomms6012.pdf

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwiE783HusrWAhVCuo8KHWr-ANQQFghJMAQ&url=http%3A%2F%2Fsustainableagriculture.net%2Fwp-content%2Fuploads%2F2015%2F12%2FSoil_C_review_Kane_Dec_4-final-v4.pdf&usg=AFQjCNHHbTrgsK95g-FL9AFlOqmwG8u85g

http://www.wamis.org/agm/meetings/wocald06/S4-Sessay.pdf

I believe that there is a relation between climate change and sustainable agriculture culture.

The question asked by Dr. Kumar is very good and of practical usefulness. Though organic matter enriches the soil fertility and improves soil physical properties it is not a guarantee of good crop production because it depends many other factors as well. Sustaining some good organic matter soil content requires very good management practices and all organic materials must be plowed into the soil.

In my view, there are two main advantages of organic matter. 1. it softens the soil so that the plant roots penetrate easily and 2. it releases nutrients slowly to the soil so that with time to time plant absorbs these nutrients. the fertilizers we give to the plants are leached down, absorbed by weeds, etc so organic matter is a better option. 

Soil organic matters are good for long term soil health.

I agree with all RG colleagues.

Not always the best for the  crop.

Response of the crops to the management of organic matter - M.O. depends on several factors. Climate, soil moisture, soil texture, degrading organisms of M.O. quality of M.O.

Soil fauna is more important factors in the process of making nutrients available to plants. Secondary factors of the addition of M.O. in the soil are: improved water and nutrient retention, increased soil aggregation and aeration, pH changes.

Here are some interesting readings: 

http://landresources.montana.edu/nm/documents/NM8.pdf

https://link.springer.com/article/10.1007/s11104-016-3031-x

https://link.springer.com/article/10.1007/s00374-016-1174-9

The use of organic materials such as manure, crop residues and the re-entry of weeds, urban waste, green manure and other plant materials is required. Their decomposition of the humus commonly called black matter constitutes not only a considerable stock of carbon more also on the physical properties of the soils by caogulation of the clay. It also increases soil capacity for water and ease of air circulation in compact soils. Humus is an agent of absorbing power and brings and maintains the microorganisms essential to the reactions of the soil. It is also available for mineral solubility research. This contributes to the formation of humus commonly called black matter

Indeed, the origin and composition of the organic material to be added to the soil is essential. The cycling time of the organic material is directly related to its recalcitrance, C / N, C / P ratio, the presence of agrochemicals and soil microbial activity.

Organic material is so important been the store house of many essential nutrients

Presence of agrochemicals (insecticides, herbicides, fungicides, etc.) in manure or another natural source of M.O. may have a greater impact on crops because in most cases, these compounds have residual effects on the soil and consequently can cause toxicity in the crop.

Dear Adijailton,

I view the chemical fertilizers have more toxins than the organic fertilizers. In 1993, I visited China's Department of Agriculture to sale some US agricultural products.

Some officers asked me that they imported fertilizers from the US. But, made much farm land became hard soils and can not be used any more. They asked me why? I contacted a PhD who is a fertilizer expert and he told me that the chemical fertilizers killed all of the lives in the soil. Without living creatures in the soil, the soil is a dead soil.

Before fertilizers be produced, the whole world used organic fertilizers. What do you mean toxicity to the corps? In Chinese history, there were prosperity dynasties with excellent harvest.    

Frieda

Organic matter has useful function in soil and plays an important role in many of reactions that take place in soil sediments as well as natural water. The humic substances make a significant contribution to CEC of the soils and they exhibit buffering  over a wide pH range  and help in complexion with heavy metal. Humic substances  cement clay and silt particles to form stable aggregates which influencing physical, chemical, physico-chemical and biological properties of soils. Organic matter also helps reducing undesirable side effects due to contamination of pesticides. Restoration of soil health may be possible for management of soil organic matter through conservation tillage, crop rotation, land use planing, recycling of crop residues etc.

Dear Frieda,

Indeed, soil biology is critical for the sustenance of agricultural production and for the maintenance of life.

I do not agree with the statement: "mineral fertilizers (agrochemicals) kill soil life".

What happens is that the intensification of conventional agricultural practices leads to the "simplification of agroecosystem", the diversity of species is reduced and dominance of certain groups of organisms occurs.The incorrect use of fertilizers and other agrochemicals can actually lead the soil to degradation, for example, there is a growing concern about the increase in the area of salinized soils due to inadequate management of irrigation and mineral fertilizers.

The incorrect use of fertilizers and other agrochemicals can actually lead the soil to degradation, for example, there is a growing concern about the increase in the area of salinized soils due to inadequate management of irrigation and mineral fertilizers.

When I referred to the term plant toxicity, I meant that the presence of pesticide residues in manure can be a limiting factor for the use of M.O. used as organic fertilization source. Highlight: Not all plants exhibited sensitivity to the presence of the pesticide residue under stress, except when this is a broad spectrum herbicide.

Thanks for your feedback.

Best regards,

Adijailton

Great question because it is getting people to think about matching inputs to soil requirements.  

Dr Tarafdar , your first response is not visible ,Can you please upload earlier so that discussion shapes up nicely.. thanks

Respected Sir

Soil organic matter is most important factor for crop growth and development. On the basis of my knowledge overall physical and chemical properties should also favorable for plant growth then soil organic matter will also guaranty of better crop.

Dr. Srivastava, as desired I am uploading it again...

Organic carbon comes from complex system of substances ranging from components of organic residues undergoing decomposition, metabolic products of microbes, products of secondary synthesis and humic substances

The quality of organic carbon depend considerably under which the soil has developed. The more C can be retained in soil by reducing excessive tillage, balance fertilizer application, retained crop residues in the field, control soil degradation. However, to my experience it is not easy task. The size of C pool varies seasonally and it depends on features such as soil type, vegetation and climate. The crop residues (litter) pool remain on the soil surface and is important of cycling of nutrients in forest soils, natural grasslands, and crop production agriculture. The conservation tillage or zero tillage may help for better regulation. The light fraction of organic residues has been used as an indicator of changes in labile organic C as affected by tillage, cropping practices, and environmental factor affecting microbial activity. The humus fraction of organic C are more stable therefore we should ascertain their location in the soil matrix.

The retention of organic C in soil depends on pH, kind and amount of clay and the nature of exchangeable cation on the clay surface. Organic substances of microbial and plant origin cement the soil particles together to form more stability. Conservation tillage, cover crops, crop rotation, crop residues, nutrient management, organic amendments may help in management of organic C for sustainable agriculture. We may also think for commercial humates to rebuild the organic C status in the soil.

Thanks Dr Tarafdar. I liked your feedback , some real stuff for onward discussion. My regards

I agree with Adijailton , soil life will never be depleted as long as we are adopting balanced fertilization that addresses soil fertility constraints..

Paul has raised a pertinent issue, how to equate nutrient requirement of crop on the basis of quantum of bio-available nutrients .

Dr Paul Reed Hepperly, can you please again upload your responses, I will appreciate ..thanks

Dear Adijailton,

What my comment is "I view the chemical fertilizers have more toxins than the organic fertilizers." That time in 1993, China only imported the chemical fertilizers from the US.. One of the agriculture items that I brought in was the rock fertilizer.

In my comment, I did not mention any mineral fertilizers that kill soil life. Please do not change what I said and make criticism.. I do not feel it's a proper act. Thanks. If you can correct it, it is highly appreciated. Thanks.

Frieda

Good discussion going on. I agree with viewpoints of most of the participants.

Several long term experiments on diverse crop and cropping systems have indicated that increase in production also increases soil organic C pool and improves soil quality provided that soil C and nutrient budgets are maintained. We must adopt techniques of sustainable intensification. Appropriate policy adoption is needed to promote adoption of proven technologies to build soil health. There is a need for research, education, outreach and policy interventions to restore soil organic C pool, improve quality of soils of agro-ecosystems, increase productivity, and improve environmental quality. I find several knowledge gaps in soil organic matter dynamics and pool. The most important are: 

1. Soil organic C pool must be monitored for soils to approx. 2-m depth following a standardized protocol.

2. Critical levels of total soil organic C pool and labile fraction in the root zone must be established in relation to productivity and use efficiency of input.

3. Impacts of  soil organic C pool on agronomic productivity must be established for major soils and principal crops for a wide range of soil organic C pool in the root zone.

4. Net rates of soil organic C sequestration must be assessed.

5. The amount of biomass-C needed, to maintain the soil organic C pool must be determined for different agro-ecoregions.

6. Nutrient management (N, P, S) must be determined for conversion of biomass-C into humus.

7. Social and economic values of soil organic C must be determined.

Dear Frieda,

I'm sorry. I have not changed the meaning of your comment. I would never do that. The fact is that "chemical fertilizer" is not the appropriate term, commonly, "mineral fertilizer term" is used (more suitable).

Regarding your comment, I may not have understood what you would like to express with:  "I view the chemical fertilizers have more toxins than the organic fertilizers. In 1993, I visited China's Department of Agriculture to sale some US agricultural products".

Excuse me for something.

Dear Adijailton,

Thanks for your braveness. Sometimes, what in our brain could bother us. To me, I like nature stuffs that does not harm to the environment and all creatures.

To me, you mentioned toxins of the agrochemicals. It reminded me the chemical fertilizers toxins and their impact to the soils and plants that plants cannot be planted to those lands that used chemical fertilizers for a while. It is worse than using the other agrochemicals. That's it. 

I think that it's clear between us. So, let's close our discussion. Thanks.

Have a Great Day!

Frieda

Finally I should say the major role of organic matter in the soil is  to help structural formation, mineralization, providing biomass carbon and nutrient retention which may also improve soil texture, bulk density, soil aggregation, pore size distribution and continuity, available water capacity, infiltration rate, effective rooting depth, soil temperature and microbial population. Therefore, you may definitely expect better crop performance.

Dear Anoop Kumar Srivastava, 

How should we enrich the organic matter content of the soil and to retain it as legacy carbon?

The natural biome which has the best-demonstrated ability to retain carbon is the native mixed grasslands. Grass and herbs which are perennial have the ability to generate a rich legacy of carbon in the soil. The ruminant animals and earthworms are certainly important parts of this mix as well as mycorrhizal fungi and rhizobia bacteria that flourish under these conditions. In addition, these systems naturally burn periodically enriching the soil with persistent char. I believe a mixed animal and crop production system where the forage is used in the production of animals and their products and the manures are composted and returned to the cropping system is the best mimic of the natural system and has demonstrated ability to regenerate impoverished soils. 

* How shall we regulate different carbon pools of soil vis-a-vis choice of a crop?

* How does fallow period jeopardizes the net gain in carbon through preceding crops? In the mixed crop and animal system the first crop should be the perennial grass-legume composite mixture which can be used to charge the carbon battery of the soil allowing subsequent production of crops which require high nutrient status such as potatoes or maize for instance. The continuing crop system should employ legumes and cover crops since these both reduce the erosion rate and increase biomass production which maintains the system 

* What are the options of more recalcitrant forms of carbon and their potential role in long-term sustainability in crop production? We have talked about the use of biochar which particularly makes sense for legacy carbon and can be combined with renewable energy production, In addition the ability of aggregated soil forms to conserve soil organic matter is notable in relation to this liming acid soils is very important as persistent organic matter is a function of calcium and clay content. In addition to liming acid soils, the ability to remediate sandy soil should be considered. The absence of clay in sandy soils compromises the recalcitrance of the soil organic matter. This is particularly important since in arid regions the clay and organic matter is the chief mechanism which can improve water capture and use. Ultimately water is the most limiting factor in our world agriculture systems

I believe, green manure and crop residues are the potential organic amendments. We can also concentrate on FYM. Moreover, in sodic soils  we have huge inherent calcite (CaCO3) precipitation, we may try to dissolution of these calcite by natural means to improve C status. Beside this, use of cover crops such as clover and small grains improve the soil organic carbon content. These cover crops also act as mulch and help in maintaining optimum temperature and moisture in soil and improve soil organic matter content through creating ideal conditions of microbial activity. Cropping systems provide an opportunity to produce more biomass C than that under mono-cropping. Inclusion of green manure crops in rotation, improves the soil organic matter status and microbial C. Growing legumes in rotation helps in increasing the productivity, and maintaining ideal C:N ratios and soil organic matter. Certain enzymes such as urease, catalase, phosphatase, and peptidases of various types help in biochemical reactions. We should also try to improve their status in the soil to maintain good organic matter content.

Not tilling the soil and breaking it up and allowing Oxygen and Sunlight to break down the organic matter is the only practical way to preserver and increase organic matter in the soil. 

While soiling crops, fallow and compost all work they don't work as fast as tillage destroys organic matter in the soil. There is not enough manure and other compost to cover very much ground. Planting soiling crops and fallowing the land cost more production than improve the soil.

A farmer should use all the manure and compost they can and incorporate a fallow season in some crop rotations on my own place and others like like it the only way I have seen that increases Organic Matter in the soil long term is no-till farming.

Yes, without any doubt provided other crop production factors are favorable. Sorry for inconvenience.

Let us know , what are those conditions , soil or plant where despite high organic matter content of the soil, crop performance is not up to mark..?

Yes, definitely SOC is the soil conditioner that enhances the soil buffering capacity, water holding capacity and improve nutrients dynamics

Article Litter decomposition dynamics in Foothills Agroforestry Syst...

The conditions may be many like soil and water salinity, hampered irrigations, the toxic effect of any element, hard climatic conditions, plant diseases, insect attack, any epidemic, poor land preparation, inappropriate sowing times etc.

Sodic soils are generally low in organic matter. Addition of organic matter and crop residues in the soil helps in improving and maintaining soil structure, preventing erosion, and supplying essential plant nutrients besides reclaiming the sodic soils, Organic material and roots of plant generally help in biological activity in soil. Organic amendments on decomposition increase in partial pressure of CO2 and produce organic acids. These process help in electrolyte concentration, mobilizing calcium through enhancing the solubility of soil calcite, lowering pH and ESP of the soil. The effectiveness of organic amendment ( crop residues, FYM, green manure, poultry manure etc.) depends upon the amount of CO2 produced and extent of reaction. To achieve  more benefit of organic amendment, submerged conditions should be maintained during the course of their decomposition to lower the redox potential. Due to their course texture and slow decomposition , these organic materials do not allow the pores to be clogged and make the soil porous by maintaining channels and voids which improve water penetration and facilitate leaching of salts out of the root zone.

Tarafdar Sir,

Good points to discuss. Addition of OM to Sodic soil will improve its properties such as structure and infiltration.  To have more benefits from OM you have suggested maintenance of submerged condition. I strongly oppose this.  During decomposition, Organic matter under submerged condition produces methane which is a potential GWG.  Organic ammendments you have indicated have to be composted before application to any fields and during the decomposition on surface / in pit CO2 will escape to atmosphere otherwise it would convert to methane under submergence.  No doubt CO2 is also a GWG, however, it is 8 times less danger than methane.  Moreover CO2 can be trapped by plants but con't  the methane.  Hence I strongly oppose addition of organic amendments (un-decomposed) to submerged fields. I always stress for making compost before the application to main fields. 

Thanks

Dr. Rajkumar, my point is the primary object of reclamation and management of salt affected soils is to reduce soluble salts and exchangeable sodium to permit ideal plant growth so that the productivity of the soils is restored. For that, replacement of excess Na ions from the exchange complex and leaching out of salts below the root zone are to be accomplished. Organic amendment can help on the process besides the provision of adequate drainage. The beneficial effects of raw organic material ( say straw) in a sodic soil under submerged conditions are: 1. The decomposition of organic matter, evolution of CO2 and certain organic acids.  2. Lowering of pH and the release of cations by solubilisation of CaCO3 and other soil minerals.  3. Replacement of exchangeable Na by Ca and Mg, causing lowering of the ESP.  Organic matter when applied in conjunction with inorganic amendments or when applied alone in soils of mild sodicity, have proved beneficial. Thus their use in reclamation of sodic soils occupies an important place.

yes, I think so

Bringoli Sir,

Composting in stalls is OK but in lagoons again the same methane emission problem?

I fully agree with the view of Dr. Brignoli,. Microbes act as an agent for the degradation of plant residues with concomitant release of nutrients and CO2. Moreover, they serve also as a labile pool of nutrients although the size of the microbial biomass carbon may account only for 2% of the total soil carbon. Soil enzymes are important fraction of organic matter because all biochemical reactions are dependent upon or related to them although they are quantitatively minute. Because of the complexity and variety of substrates they serve as energy source for the microorganisms. Each soil may have its own characteristic pattern of specific enzymes. Certain enzymes are virtually found in all the soils. Typical examples are urease, phosphatase, catalase etc. Dehydrogenase activity appears to be related to the quantity of decomposable organic matter and is closely related to the soil biomass ( Stevenson and Cole, 1999).

Crops planted on soils containing high OM are healthier. Enriching SOM requires addition of animal manures, green manures, farmyard manures, biochar, leaving crop residues in the field, mulching and reducing the possible causes of SOM loss. The major causes for loss of SOM is soil disturbance during tillage operation. Therefore, avoiding soil disturbance by practicing conservation tillage practices may reduce SOM loss. Crop residues can be used for two purposes

(a) as source of SOM

(b) serves as a mulch to protect soil from direct UV-radiation

Oxygen is a fuel in SOM decomposition. Thus, increasing frequency of tillage means like adding more fuel to fire; it accelerates SOM decomposition apart from disturbing soil structure. 

Birhanu , Dr Tarafadr , and other colleagues, fascinating responses , but most of us have touched only the response of organic matter on crop . How do you reckon the sink capacity of different soils with regard to organic matter   over time..?

Soils of agroecosystems have a C sink capacity which can be filled by sequestration of atmospheric CO2 as soil organic matter (humus) and as secondary carbonates. Transfer of atmospheric CO2 into soil as soil organic matter and as secondary carbonates through input of biomass-C and the nutrients (N, P, S) required to transform cellulose and lignin into humus (Lal, 2004a; Lal 2008). The soil C sink capacity, which can be filled through transfer of atmospheric CO2, is equivalent to the amount of C pool that has been depleted since conversion of natural into managed ecosystems. Sequestration of C in soil occurs through creation of a positive C budget. However, the rate of formation of secondary carbonates, in arid and semi-arid climates is low and may range from 2-5 Kg C per hectare per year ( Lal 2004a). Rates of soil organic C sequestration vary among climate,soil type, land-use and management systems range from 100 to 1000 Kg C per hectare per year. In general, the rate of SOC sequestration is higher in cooler vs. warmer climates, heavy-textured vs. light-textured soils, deeper vs. shallow profiles, poorly-drained vs. well drained, and in foot slope vs. side slope or summit landscape positions. 

Dr. Anoop, that is an important point we missed. Soil OM sink varies with soils. Some soils retain OM for a long period of time while others expose it to decomposition process. Soil OM sink is better in clay soils than sandy soils as the later contains more air that accelerates oxidation process. Besides, clay soil forms better aggregates than sandy soils that protects OM from microbial attack forming "protected OM". If there is no gradual OM sink in soils, addition of OM to the soil alone has no profound importance. We know that OM is usually recommended to be added to sandy soils to improve its physico-chemical properties. Though you add OM continually to sandy soils, its OM sink over time might be still very low. Here, I remember a phrase "Garbage in garbage out". Therefore, soil type greatly affects OM sink capacity of a soil and plays a great role in determining soil health and crop performance. 

Your question suggests that you have a fundamental misconception about soil carbon and OM.   'Soil carbon' has two components.  

one is the bio-active component (referred to by other respondents) which provide all the nice nutrient recycling features.  It also provides the organic 'glues' which form soil aggregates to give soil its structure.  This component will 'cycle' ie will decompose and be eaten and excreted by organisms.

The other component is essentially charcoal - it has no bioactive property at all. while it can adsorb some nutrient (useful in a pure sand soil)  , it has no other useful properties except to 'dilute' the soil matrix. ie a heavy clay can be made more workable by large amounts of charcoal. This component does not cycle, has no biological value and will last 10,000years.

Unfortunately 'soil carbon' is usually measured by incineration and the result includes both types.    To make sense of soil carbon reactions, you need to know the proportions of each component. 

Do you consider  soil organic carbon and soil organic matter as two different sides of same coin or otherwise..??

Soil organic matter is plant roots, worms, bacteria, algae etc and their decomposition products and excreta .   Soil organic carbon is the carbon content of soil organic matter as measured when it is burned in a soil carbon test.    the problem I referred to is that some soils contain significant fractions of carbon which is NOT organic matter related.  this carbon plays no part in OM cycling or in nutrient cycling. It is chemically resistant and remains constantly in the soil for VERY long periods (centuries ).   The problem arises because a conventional soil carbon test (ie heat to 600C in oxygen and measure CO2) measures this stable carbon fraction as well as normal OM.   many Australian soils have low OM and nearly half the soil carbon is this inert component.  So normal soil carbon tests overestimate OM significantly

Which parameter, you consider more indicative  of active  carbon  in soil.Is it organic carbon if OM is over-estimated..

If you are measuring organic carbon directly then there should be no issue .   Of course, there are multiple ways for OM to interact with a crop - some direct (eg supply of nutrients from OM decay) some indirect (worms, mites , bacteria make pores in soil which help water absorption , storage and transmission which in turn affect crop production.)

Example: from 1980 onwards we have introduced minimum/zero  tillage and stubble retention to cereal farmers in southern Australia.    This has caused a big increase in OM, and an increase in yield.  But it has also improved soil aggregation, which increases surface soil  rain infiltration rates and water storage.  The resulting increase in yield is almost completely accounted for by the additional capture of  rain in the two months after seeding.  A side effect is that sloping fields which previously needed contour banks to prevent erosion , now does not need the banks.

Yes you will get a good correlation between soil OM and (say) yield but that does not explain HOW it is happening.

These are complex systems with many (apparently) unrelated things interacting to produce the result.  that is why many scientists are using models to deal with all the complex interactions simultaneously. 

I think,  the pools of C in the sedimentary rocks are relatively inert, and change over a scale of millions of years. Pools of C  in terrestrial biosphere ( soil, vegetation), atmosphere, and upper layer of ocean are active pools. These pools are vulnerable in human activities. Exchange of C among these pools, called the Global Carbon Cycle, occurs at long and short time scales. Exchange among the inert pools occurs over a time scale of millions of years, and is referred to as geologic or the long-term C cycle. The exchange among active pools refereed to as the short term C cycle.

Dear Cliff,

You made a different discussion point. Interesting. First of all, why you compare soil carbon and OM? Soil carbon is a general term; might be organic carbon or inorganic carbon. If you are referring soil organic carbon (OC), are OC and OM different things? Percent OM is derived from OC regardless of the type of OC whether bio-active or not. If you got a new research finding, please show us the link so that we learn more.  As carbon that is not related to OM is inorganic carbon. When I talk about OM decomposition or recycling, by default I mean the OC. During this discussion, I am dealing about the OM that is derived from plant and animal remains. Further classification of OC into bio-active and charcoal might be happened during biochar production process; to mean bio-active OC is the one found in the fresh OM used as input for biochar and charcoal as one of the outputs of pyrolysis.

Besides, you mentioned the bio-active component of carbon as source of all nice nutrients and forms soil aggregates. In fact, it plays significant role in soil aggregation. But how carbon becomes a source of nutrients? It is OM that contains carbon and other organic form of nutrients.

Nice response Dr Tarafdar , he has opened up the discussion further with regard to soil C pool vis-a-vis other C pools ...

Birhanu , i agree with your statements. If bioavailability of other nutrients , we consider ; why not bioavailability of C as well , regardless of active C pool or passive C pool of the soil..

followed a question

Actuallly C in soil organic matter pools are from litter (crop residues), microbial biomass, faunal biomass, below ground plant constituent, water soluble organics, stable humus whereas other C pools are from lithosphere (sedimentary rocks), hydrsphere (oceans), Geosphere (fossil fuels) and atmosphere. Soil C pools can be considered as Biosphere C pool.

To maintain soil carbon sequestration for soil microorganisms soil organic matte as humus is essential  for the life of the soil in the ecology of nature of the earth the store house plant nutrients composed of lignite as carbon -protein enzymes of microorganisms which transform essential nutrients in the root hair of plant in ionic for nutrition of plant to complete the the food of the ecology of nature from lower trophic small microorganisms to higher trophic animal and human.

So, for sustainable soil health management for soil fertility and productivity of crop  there is no alternative to organic recycle organic matter to form humus the life of the soil and living-beings in this planet earth.

The participants of the discussion are expressing very good views that can be highly useful for all of us.

Dr. Karan, I fully agree with you. A severe depletion of SOC pool in soils especially in India and most of the developing countries is attributed to the widespread use of extractive farming practices where the plant nutrient removed in harvest ( crops, fruits, timber etc.) are not replaced. Indeed nutrient removed by harvest must be replaced by adding/ recycling biomass and or applying organic/inorganic fertilizers from outside. The rates of SOC sequestration vary widely, and depend on soil type, climate , cropping system and the site specific management. Measured rates of increase in SOC pools ranged from 0.1 to 1.4 Mg C per hectare per year. Stability of SOC sequestered depend on the degree and strength of soil aggregates, and use of any organic amendments. I feel, there is a strong need to strengthen the data bank with regards to the judicious management of soil fertility for increasing productivity, improving SOC pool, and enhancing nutritional security.

Organic matter decomposition and  recycling to transform    humus as lignite carbon and protein as enzymes of microorganisms which transform essential nutrients from soil to root hair of plant for nutrition   very much essential for sustainable soil health management  in relation to soil fertility and productivity of crop. Pool of organic matter in  active form of  C:N ratio 15 to 30 for 1 to 2  years, passive pool of organic matter in slow process for  15 to 100 years with C:N ratio 10 to 25  and very slow process

for 500 to 5000 years with C:N ratio 7 to 10. .

Certainly soil organic matter is a great boon for the crop performance. That was the reason compost has become so popular in olden days where no hi-fi fertilizers were discovered. One RG friend mentioned litter, is the best source. Or gather dried leaves that fall, dump all in a small soil ditch along with  the vegetable waste, if possible cow dung even dried also no matter  (we follow the same at our home garden, it works excellently). Once it rains automatically it becomes natural compost. Put few earthworms if possible then there would be possibility of increase in the vermi-compost level. Ultimately it increase the soil fertility and better source. Simple eg. in forest nobody keeps manure still thick vegetation. Only source fallen leaves become litter as time pass. 

How to enrich garden soil with organic matter.

(https://www.gardenia.net/guide/how-to-enrich-my-garden-soil-with-organic-matter)

HOW TO IMPROVE GARDEN SOIL WITH ORGANIC MATTER

(http://www.dummies.com/home-garden/gardening/how-to-improve-garden-soil-with-organic-matter/)

The Dirt on Soil

Garden Soil: Why it Matters - Making it Great

(https://www.thespruce.com/the-dirt-on-soil-1403122)

water is the key element of all life on earth. Soil organic matter increase water holding capacity. Some other important benefits are as follows.. 

controlled release of nitrogen

accelerate growth of  soil micro flora, bacteria and fungi both.

These micro flora increase availability of Phosphate and other nutrient.

So, I think all essential retirement of plant is affected by soil organic matter. 

Good discussion point by Abhishek

Dr. Abhishek, saw dust can be used as manure, it can absorb water also. It has good manurial value specially in sandy soil. Only disadvantage is, it has wide C:N ratio, thats why it is better to mixed with manure or nitrogen supplement for decomposition so that you may use as nutrient supplement and moisture retention to your plant. The other possibility is you may spread saw dust to animal shed and urine soaked saw dust can be a good manure for use of crop plants. Then probably you need not have to add any additional N for decomposition.

When dealing with organic wastes transportation costs become a big issue. The ability produce the organic amendment makes a convenient and cost-effective methodology. In terms of transporation of manures from concentrated animal production. Concentrated  manures are best coupled with a composting process to lower the volumes and linking the animal production systems with surrounding field production of the crop component. While nutrient loss is an issue from soluble fertilizers and raw manures this is much less of an issue with compost utilization. When soil organic matter is low the ability to retain and recycle nutrients is also compromised. Raising soil organic matter makes the nutrient cycling less leaky. The effects of soil organic matter conform to a curve of diminishing returns. The greatest improvements occur when soil organic matter improves from 1 to 5% while the positive effect is much attenuated above 5% soil organic matter. 

Thanks Abhishek for tossing up this issue, which is so important in the context of whole discussion. Lets debate this issue in depth . What could be the soil conditions that despite high organic matter content of the soil, crops fail to observe any  fertilizer  response..?

Organic matter as humus composed  lignite carbon and protein as enzymes of microorganisms which transform essential nutrients in the root hair of plant in ionic form for nutrition of plant; maintain carbon sequestration for soil  microorganisms which is essential for sustainable soil health management for long term soil fertility and  agricultural crop productivity. So,organic recycling of organic matter in fertile soil play a key role for sustainable agricultural production for the ever growing population of the planet earth.  

"Soil conditions that despite high OM content, crops fail to observe any  fertilizer response"

Failurity of crops to respond to fertilizer application in high OM containing soils might be due to:

(a) Already high nutrient content in the soil making less response to external nutrient supply

(b) Low water content in the soil (because applied nutrients are made available to the plant only in solution form)

(c) Water saturation above the normal restricting respiration of plant roots

Thanks so much gentlemen, Karan, Birhanu , Hussein ,  and other learned colleagues but our major concern with organic matter is the kinetics of nutrient release and their implications on nutrient dynamics vis -a-vis crop response . Whether or not , rate of humification of accumulated organic matter will influence the magnitude of  crop response ..??  In some of the acidic soils , we have observed response of nitrogen , even though organic carbon is 2.5-3.0% with pH reading as 5.2-5.8 under typical humid tropical climates

Soil organic matter is the storehouse of nutrients both macro and micro and it is composed of phenols ,fluvic and humic acids ,hemicellulose,waxes which impart positively on soil physical,chemical and biological properties.However,the management of organic materials applied to soil will determine its sustainability ,for instance ,application of plant materials such as rice bran,sawdust and mulching materials with high C/N ratio to soils which can not decompose easily will encourage the soil microbes to feed on organic matter in soil leading to depletion a d I suggest that these materials should be processed to encourage quick decomposition also ,they can be mixed with poultry ,pig,goat manures with low C/N ratios to enhance decomposition .In addition,the use of chemical fertilisers destroys soil properties including organic matter on continuous basis without soil testing .Also management soil organic matter in the tropics is a serious problem because of kaolinitic soil clay structure with little negative charges on soil colloids which causes low CEC and poor fertility and it is only soil organic matter that can supply negative charges to increase soil CEC  and soil fertility .Finally. the farmers should adopt appropriate cropping systems that encourage soil cover against erosion, controlled policy of not clearing large expanse of land in which the farmers can not control erosion and weeds and use of tillage implements that will not scrap all the top soil which contains the nutrients and massive removal of trees for soil productivity and enchancing food security

Definitely help organic matter to improve the soil .. Greetings

CARBON, HYDROGEN, AND OXYGEN PERMEATE ALL LIVING MATTER INCLUDING EARTH AND ALL ITS ORGANIC PROPERTIES.

Humic and fulvic acid fractions have direct growth regulator effects at low concentrations of ppm such as germination stimulation in term of speed, vigor and percentage.. Although most discussion has concentrated on nutrient, the effect on growth regulation is profound. Humic and fulvic acids stimulate root and shoot growth and they have demonstrated ability to stimulate chlorophyll and photosynthesis. Humic acids and fulvic acids can remediate toxicity reactions and are key chelators and mobilize the difficult to solublize nutrients such as Phosphorus. There is a building literature on humic acid and fulvic acids stimulating plant defense reactions. The targeted use of these humic materials in conjunction with nutrients is a way to make its use both economic and efficacious.  When plants are affected by toxicity the use of humic/fulvic acids and soluble kelp is an organic approach to providing detoxification, feed and growth stimulation. For conventional farmers the use of the same and soluble foliar fertilization can be very useful for plants particularly when under stress and at critical plant development stages. 

Excellent idea Dr. Paul. Humin fractions may intimately bound to mineral matter ( e.g. clay). It has high C content (>6%) and also contain fungal melanins. The humic acid in general have 54-58% C and 0.8-4.3% N; the fulvic acid contains 41-50% C and 0,9-3.3% N. We may take advantage of it.

Crops requiring low chemical fertilizer are to be encouraged. A legume catch crop may be planted during fallow period. In tropical areas, particularly during scorching summer, a legume catch crop is beneficial. Soil temperature remains low. The nutrients released from soil after wetting is captured by catch crop roots and it is beneficial. Instead of summer ploughing, research effort should be directed to identify suitable cropping system for ecological control of weeds, insect pests and pathogens. Reduced tillage is recommended for conserving soil o.m. But reduced tillage may provide a coarse seed bed. It is difficult to get good crop stand, particularly for small seeded crops. In that case we have to think for crops with bigger sized seeds which are suitable for coarse seed bed. It is difficult to enhance and maintain soil O.C. But if we enhance soil OC, itself can ensure good crop yield.

Organic matter as humus the store house of plant nutrients composed lignite carbon and protein as enzymes of microorganisms which transform essential nutrients in the root hair of plant for nutrition. So, for carbon-sequestration for soil microorganisms is the essential phenomena in the ecology of soil .. Generally; 24 mg of carbon required by the one soil microorganism which transform nutrients from soil to plant root hair in ionic form for nutrition. Out of  these carbon 16 mg evolution    through enzymatic oxidation of  carbon to carbon-dioxide to the atmosphere from body of the microorganisms ;rest must be utilized by the microorganisms for most essential  philological function of body. So, carbon as sequestration of soil microorganisms generally utilized from organic matter as humus is most essential component in a living soil ecology mechanism of the nature in the planet earth. Nitrogen fixing symbiotic bacteria  in Legume-Rziobia association in presence of Molybdenum catalyst  fix elemental nitrogen in soil from the atmosphere.Non-symbiotic bacteria like Azotobacter and Clostridium also fix atmospheric elemental nitrogen in soil. So, all these nitrogen fixing bacteria also required carbon sequestration from organic matter as humus the life of the soil in the ecology of nature in the planet earth.    

The organic matter enriches soil with nutrients, beneficial microorganisms, etc., that promote the overall soil performance.

Best regards

Anoop,

Incidentally, I was reading a book yesterday, which was related to your question and I would like to share the contents.. It was a culture prevailed in South India among farmers to rotate the crop production to a variety of crops to keep the soil organic and fertile. Farmers of those days, even researched and found out the carbon content of certain trees and leaves in the eco system and used to put those healthy leaves and trees in the land prior to crop to ensure the land's soil carbon content are healthy enough to yield a good crop. Even today's farmers of villages follow many of these old cultures, which are not known to the academic world. Please continue to explore in this good are, which is a need for this hour.

Best Regards.

Dr. Sekar Gopal.

SO ORGANIC MATTER AS HUMUS IS LIVING SYSTEM OF SOIL  MUST FOR A FERTILE SOIL TO MAINTAIN SOIL CARBON-SEQUESTRATION FOR SOIL MICROORGANISMS IN THE ECOLOGY OF THE SOIL IN NATURE.

Good day. This is a rather academic issue as most farmers wil have a tough time to build the carbon content of their soil. If a farmer starts farming at age 20 and plans to retire at age 65, it gives him 45 seasons to build his carbon in his soil. Then it becomes quite important to do enough each season in order to make a differance at the end of the day. 

we mainly farm on sandy soils with a density approaching 1.6. 

we have little if any carbon on our soils.

our average carbon is around 0.001%. 

on 1 x ha (30cms deep)   = 4800 tons of soil. 

= 4.8 tons of carbon. 

So in order to lift carbon with 1ppm its important to look at:

the carbon content of the ammendment being used.

the qty of actual carbon being applied.

where the farmer wants to be ppm wise per ha.

The cost per season for applying the ammendment.

So as is clear a couple of kg's of carbon per ha per season will not easily change the agronomic performance per ha. 

This is my experience. I share is gladly. 

Friends, thanks for such over-woover-whovover-wheoveover-wheloverover-wheover-over-whelming response , I appreciate your participation.

Let us know, why don't we have different diagnostic levels of soil organic matter vis-a-via different crops..