Potential of various carbonized organic matters as peat substitute in growing media and soil amendment for wheat and sunflower cultivation

Biochar is a stable carbon-rich by-product obtained by pyrolysis of various biomasses. Its use has been recently suggested as peat substitution in potting substrates because of some intrinsic similarities with peat, while the addition to soil as an amendment lacks in open field experiments in the Mediterranean regions. Furthermore, only few studies on biochar impact on crops quality have been published, especially under field conditions in temperate regions. This work aims to test the potential of selected biochars from different feedstocks, and a composted biochar, to partially or fully substitute peat for tomato and basil growth in a nursery trial. In the case of basil, the assemblage of volatile compounds of basil as well was checked. This work also focused on the effects of biochar as soil amendment on the yield and the content of some nutraceutical compounds of wheat and sunflower. Overall, I found that high doses of biochar cannot be used in potting substrates for tomato and basil seedlings without negatively affecting their growth. Nonetheless, small doses are not harmful, and on a global scale may represent a precious contribution for preserving the remaining peat resources. The volatile organic compounds of basil were not significantly affected by biochar addition, even with 25% of peat substitution with biochar and up to 50% with composted biochar.. Conversely, high doses of biochar can be added as soil amendment for the cultivation of wheat and sunflower without negatively affecting their growth and nutraceuticals compounds, but this environment-friendly strategy is not feasible from an economic point of view.