Using chars of different sources become more similar when charred than the difference in the source organic materials. I would think you would have no problem of using those organic materials as chars to supplement your composts. Char and compost can be quite alkaline and you might get a deficiency in micronutrients. To avoid such issues the use of sulfur could supplement the final compost to adjust pH to 6.5 which would be optimal for tomato production.

Yes you can... I agree with Paul.

I have a general problem understanding the motivation for this approach.

Tomatoes and peppers have a high water content. To convert this wet organic residues into biochar you would need a lot of energy to dry before receiving a little amount of coal = biochar? How does the energy balance look like? Is this biochar not almost like an ash material? What is the carbon content of such a biochar?

One of the most mentioned advantages of biochar to my understanding is that it is sink of carbon as it is very persistent to mineralisation or decomposition. Would this still be the case in a biochar derived from tomato and paper waste?

I think...you can use Biochar for tomato and pepper. Paul's suggestion is good!

Biochar for Horticultural Rooting Media Improvement: Evaluation of Biochar from Gasification and Slow Pyrolysis

Agronomy , Vol 7, Iss 1, p 6 (2017)

Hi Khalid,

You should read the paper by Blok et al. see reference above! The EC and K levels are extremely high for greenhouse residues( Tomato stems/leaves etc)You will find the levels are way too high,at least 10 times higher than wood chip biochar. Admittedly they used slightly higher temperature and temperature can effect EC.This will limit you as to how much can you use, perhaps a few percentage.Try it on a few seedlings first.

Hope this answer helps

the biochar obtained from Tomato residues is very rich in K content. When you used higher temperature the pH of it becomes very high. Therefore you shoud be carefull about its very high pH.

For Morocco an environment with potential for alkalinity the generation of char at 400 or less will assure a more neutral pH which should not interfere with pH and micronutrient issues.

The ideal biochar would link gas and liquids for renewable carbon fuels with the char for soil and compost improvement.

The combined system can generate energy more than it takes and result in a residual in the soil to give long term soil improvement.

Thank you all for your valuable contributions. In fact, the scope of this question comes from the output of a paper I published before Article Agro-environmental assessment of composting plants in Southw...

Tomato wastes are mainly pre-dried leaves and long lignified stems with less water content. Their composting is already done with satisfactory results, but producers are turning back to soilless cultures fearing nematodes and soil alkalinity and high EC. Thus, producing compost from those wastes could be relevant for carbon sequestration, but for soilless system it's not. The option for recycling those wastes would their transformation into biochar in addition to the compost to obtain 100% recycled and stable substrate. No way for peat, coconut, perlite...substrate because they're indeed stable but expensive and not sustainable as carbon footprint is concerned (we export water as tomatoes and import organic matter as peat for-instance!!!). Michael Quintern said that the energy balance is a problem, in fact yes in case of fresh recycling, but we use to recycle wastes after open field pre-drying and ignition of pyrolysis in traditional plants. As a consequence, it could be rather used a heat source for other concerns.

pH, EC, high K content all are factors that should be taken into consideration as Dr Hani Antoun