if only a very bad one, because it lacks any biological activity and does merely participate in the SOM cycle. We had this discussion over many years for the addition of plastic materials like polystyroles (styropor / hygromull) or acrylamides.

Chars (of which biochar can be included) are already a part of the soil OM pool, with their relevance being dictated by the particular location/ climate/ agroecosystem. Many soils already have a large C component from natural (ie wildfires) and anthropogenic sources. There are many many papers now describing the role of biochars in C and nutrient cycling, priming interactions, stabilization of native C etc. There is no short nor simple answer to your question. Yes, biochars play a role in the SOM pool, do they they function in the same way that root or crop detritus, or SOM does? ..not so much. Please email me if you need some good papers on this topic.

Lukas

Do not think they are substitutes but could be better envisioned as complements. Biochars work best in acid soils and they should be employed with caution in alkaline soils or procedures of generation should be monitored in terms of temperature and time to assure a alkaline issue is not worsened.

In true sense, biochar could not be considered alternative of organic matter in soils due to a number of reasons, like less microbial activity and least release of nutrients during its further decomposition etc.

I do not think biochar could be an effective alternative  to organic matter , simply due to alkaline nature , lesser  initial microbial load and nutrient concentration as well , as nicely narrated by Dr Schnug, Dr Hepperly and Dr Ghafoor.  Rather , its effectiveness is more inconsistent  on alkaline calcareous or saline /sodic soils.

One of the best uses of biochar would be in the complementary inclusion into compost of plant and animal wastes for their stabilization which will also give them both longevity as in the Terra Preto or AmerIndian Black Anthrosols.

When we use manures beneficially the optimizing of their nutrient aspects is further by organic matter and mineral materials which are composted in a way that their nutrient content is conserved.

This I believe is one of lasting lessons of Terra Preto for modern peoples can apply.

Biochar cannot be an alternative to SOM. In fact, it is part of SOM. It is a kind of stabilized SOM. From all I've read, I consider biochar to play a significant role in enhancing the nutrient and water retention capacities of acid soils which are dominated by low activity clays. Although biochar has been reported to contain labile forms of SOM it cannot replace SOM in its function as the main source of food/energy for the soil microorganisms.

• Biochar as a medium is itself not innoculated with the proper biome for the particular plant(s), nor may contain the adequate Ph, minerals, and such.  Recent studies have even suggested that productivity of certain crops have increased only with concentrations of no more than 5% within SOM.  Perhaps the question more appropriate would be asked if an innoculated, Ph balanced biochar can act as a medium to hold plants in a hydroponics system that is constantly fertigated.

• Biochar as a medium is itself not innoculated with the proper biome for the particular plant(s), nor may contain the adequate Ph, minerals, and such.  Recent studies have even suggested that productivity of certain crops have increased only with concentrations of no more than 5% within SOM.  Perhaps the question more appropriate would be asked if an innoculated, Ph balanced biochar can act as a medium to hold plants in a hydroponics system that is constantly fertigated.

As Kevin pointed that few options to use in hydroponics. Biochar has large number of S,R,C,T shape pores with different size and length which is similar to biomass. Its ability to store, sustain and pass through the any flux of nutrient and water. It will help to improve soil moisture and nutrient holding capacity of any soil. Inorder to feed burgeoning population. Hence we can amendment biochar in arid soils at  2% levels and other soil types it is restricted.

The logistics of slugging around and processing so much biomass as illicit in biochar  seem daunting to me.

I think people need to return the organo mineral complex and its profound ability to extend the longevity and functionality of organic matter as humus.

Once organic matter is conclusively combined with clay the longevity of the Carbon can go from just years to millennium.

The ability to return the clay and silt fractions are best initiated by linkage with polyvalent cations especially Calcium from gypsum which is plentiful and does not alter the soil pH.

Many areas have abundant clay in subsoils even when sand is dominanting the top soil layers. Manure composted with 10% clay or silt 2% gypsum and 1% mature compost will seed the miraculously ability to conserve the soil structure and organic matter while minimizing losses in the compost process.

 Biochar is some sort of inert material as it is  a burnt material under limited oxygen conditions.There will be mass loss in biochars obtained at 300-500o C  and chemical changes in biochar obtained at 600-900o C.The biochars are porous,   have large surface area and variable cation exchange capacities.The nutrient contents in biochars are in small amount not comparable to manures .Biochars hold water and may benefit in sandy soils when applied at moderate rates say 5 tonnes /ha.We can not procure and apply very high rates(their beneficial affects were also not proved at high rates in sandy soils).The liming affect in acid soils also limited as we can not apply huge amount of biochar for acid soil reclamation.Humus in soil or in organic manures is both a decomposed and synthesized product.It has high CEC,150-300cmol/kg and high water holding capacity equivalent to 80-90% of its weight.It has buffering capacity and resist change in pH both in acid and sodic soils .The humus containing organic manures are applied to both acid and alkaline soils as amendment .Manures contains nutrients and humus(at least 30% humic material).Dr.Hepperly has very clearly mentioned the befits of manures especially in stabilized form.Humus has large capacity to hold nutrients and release them when needed.Humus also shelters vast amount  of soil microbes and sustains their life .Biochars can to some extent hold microbes but ca not feed them over time.We should not make biochars from  valuable manures or crop residues. One can make biochars from woody materials which have no competitive uses.Do we have surplus woody materials to make biochars  and bury in soil for taking care of climate change or global warming?Humus has also role improving physical conditions of soils for better aeration and water relations to crop plants apart from nutrient supply.

I dont think the biochar will replace the OM in soil as it is more stable and will not add any material to the soil with decomposition.

It is good to enhance the soil charac. but still soil need OM for elements, while biochar is not a good source for this

Yes , I agree with you Mohammad , biochar cannot replace the organic matter , when you compare the comprehensiveness of the two divergent sources.

Biochar as substitute for organic matter in the composition of substrates for seedlings PDF enclosed for further reading

Normaly char material or biochar is OM burnt or pyrolyzed with almost no chemical functionality. In this sense and because most of the physicochemical properties os soil organic matter is conferred to the soil due to its reactivity, in no way one may think of biochar as a substitute of soil organic matter. Nonetheless, biochar may be combined into composted material or applied to same soils as a ammendment to add some structure or porosity to the soil. This material cam be chemically modified to include some fertilizers that may function as a slow release fettilizer. In a nut shell, biochar is not a substitute for organic matter but have many valuable other uses in agriculture and soil remediation.