you can use biochar.

http://www.sciencedirect.com/science/article/pii/S0038071711002458

Biochar is a good point. But what if we want to use locally produced manures and wastes? Using them instead of imported material such as biochar leads to lower carbon footprint of agricultural products. If we import biochar for this purpose, the carbon footprint of our product may increase. or not? 

you may convert the manure to biochar

https://dl.sciencesocieties.org/publications/jeq/abstracts/43/4/1504

Dear Mr. Litskas,

According to your question, I see two or three options, the third is a combined option with the previous two.

A) The "PBC" - Plant based biochar.

The soil structure will be improved. The carbon content is high and stable. The micro or mesoporous structure of this material contributes to increase the water holding capacity of the soil, to fix also the nutrients and the organic carbon. Fertilization capacity of "PBC" negligible.  Potential disadvantages: 1) expensive price, 2) until now, probably modest experience

B) Spreading of organic wastes (e.g. animal manure) - until 70 t/ha manure.

Point to be considering: the humus building potential in the Mediterranean area is probably not the same as in temperate climate zone due to composition of natural plante detritus, higher temperature, lower humidity.

Cautions required:

1) Layers analysis of clay soil profile under natural shrub vegetation / natural forest with a strong organic litter on the Cyprus Island 

2) Presence or not of the aerobic microfauna (fungi) responsible for the decomposition of organic matter (at the surface, on the top layers, layer 1)

3) Presence or not of earth worms responsible for the humus formation (layer 2)

4) Presence or not of bacteria for the mineralization of the organic matter. Activity too high not desirable. Avoid mineral nitrogen fertilizer promoting the proliferation of bacteria (layer 2).

5) Presence or not of an  abundant root zone under the humus layer (layer 3) - prevent nitrogen leaching

6) Converting this logic from the forestry modus to the agriculture modus in an appropriate way taking also time into consideration (min. tilling, mulch, associated crops, permanent vegetation cover, high amount of org. wastes, no mineral nitrogen fertiizers).

C) Combination of variant A and variant B.

Good luck and best regards,

Etienne 

Yes you can do it by using manure. Obviously increase will depend by the total amount dosed and by starting C soil content. 

I disagree about biochar use because it is not safe for environment and soil.  

Dear Mr. Litskas,

Under Mediterranean as well as under tropical/subtropical arid climates, decomposition of soil organic matter (both native and freshly added) is relatively fast as compared to temperate cool climate. Conventional tillage is another factor contributing to the depletion of soil organic matter. Even continuous application of organic residues/manures may take several decades to increase the organic matter pool to the desired levels. A more recent and promising approach may be adopting zero-till technology combined with surface mulch (i.e. different levels of previous crop residues). I suggest you to consider this option too.

Best Regards,

Tariq   

Dear colleagues,

I would like to share a few thoughts on "organic carbon pool" (OCP) in soil:

1. Do we just want to increase the OCP by adding coal? Or do we want to increase "active" soil humus as produced by soil microorganism and earthworms? 

2. Adding fresh organic matter, farm manure, compost, and vermicompost has a positive effect on soil microbiological activity and plant growth / health. Not sure about char coal, as most of the cited papers are from locations with high earthworm populations as well. I personally believe the effects of the earthworm (casting) in these trials are not considered strong enough.

3. Cost effective organic waste management. Considering a cost/benefit approach I believe the ranking would something like (not absolutely understanding your local situation):

A: Vermicomposting (stabilised OM and highly efficient humus with humid acids etc.)

B: Composting (partly stabilised and sanitised, higher production costs than A)

C: Direct land application (not stabilised OM, lowest costs but maximum volumes)

D: Pyrolysis (highest costs, depending on temperature of pyrolysis the coal is more or less inert in the soil, coal is competing with energy prices for char coal in the local industry which can make it a very costly soil conditioner for farmers)

4. I support any reduced soil tillage system to preserve OM, earthworm activity and population, reduce soil erosion. Though shallow tillage will preserve soil moisture.

Regards

Michael

There is nothing left for me to suggest further, except to say not to allow sunlight directly to fall on bare soil surface. Always cover the surface with a vegetative mulch to protect soil sheltered flora and fauna to live happily due to optimum soil moisture. 

The High temperature in the Mediterranean regins will leads to rapid decomposition of organic matter in the agricultural soils with negative impacts to their productivity.

eventhough you will add a high amounts of organic materials, after a few months it will disappear due to rapid decomposition.

Many great notes above.  I advise that the animal manure be used to top dress a cover crop or be used to propagate transplants to the area. Cover the soil and do not til. The manures will be short lived and need to be used by existing ground cover plants. This is not a place for organic soil amendment.

In my NewLife project we proceeded to carry the heavy clay soil treatments using different types of waste using the method of reconstitution of the soils. By means of this method the increase of organic substance was carried out with a specific mechanical treatment of soils and organic waste with precise properties. The system has enabled the coating of the organic substance added with the soil mineral component (in this case clay) obtaining interesting developments concerning the stabilizzaznione of organic carbon.

The results obtained were intressanti as we have secured a significant increase in stable fraction (humic acids, fulvic acids and Umine) and a strong increase in the ratio HA / FA. The ratio of C / N was increased from 6 to 14 with a strong improvement of the soil structure and water retention. The comments, still in progress have led to the preservation of organic matter for four years without substantial losses.

www.lifeplusecosistemi.eu

So far so good Mr. Paolo Manfredi. But please check for the biological status of soil counting on flora and fauna both in quantity and diversity. This is the very object of building up of organic matter i.e., to feed soil sheltered life. OK?

Thank you Kunuthur Srinivasa Reddy.

The evidence of clay were performed on land and if initially the colonization of plant species has been poor in the year following formation of reconstituted soil, also diversity in species level was greater of land used as a witness. High initial presence of Mixomicetes.

From a microbiological point a strong increase of Azotobacter and total heterotrophic bacteria.

On wildlife we have not done thorough research if not the visual observation of the presence of earthworms greater than the witness fee.

The most significant tests were carried out with medium texture soils and agricultural production yields, as well as the colonization of herbaceous species, they have been very high.

P.S. in the accompanying video, the 1:06 minute you can see the yield in the field on three different soils, the third was a degraded soil subjected to reconstitution treatment.

https://www.youtube.com/watch?v=QsFTx_D0fZs

Dr. Litskas, it is really difficult to improve organic C  pool under arid environment. We are trying for last 12 years with the application of 4 tons/hectare organic manures per year but could only build up organic matter from 0.22% to 0.28%. 

Thank you Dr. Tarafdar, is there any publication with your experiments? it would be very interesting for us to view your results.

Kind regards.

The process is on, as soon as it published I shall inform you.

Yes it is.