Progress on the amendment in biochars and its effects on the soil-plant-micro-organism-biochar system

Biochar, coal produced by pyrolysis and used as an amendment, has several advantages and has proven to be a promising avenue for sustainable agriculture. However, the current manufacturing methods, the conditions of pyrolysis and the biomasses used produce biochars of very variable qualities which can differently affect the productivity of the ground and the outputs of plants. Currently, no study makes it possible to elucidate the influence of the physicochemical properties of the biochars on the structure and the microbial diversity of the soil. The aim of this review was to understand how the physicochemical properties of a biochar affect its capacity: to reduce the emissions of greenhouse gases; to improve the growth of hothouse plants; to improve the effectiveness of the use of manures and water; and to modify the structure and the diversity of the bacterial communities in a horticultural substrate and a mineral soil. These biochars were produced under various conditions. The analyses show that the addition of biochar can stimulate certain groups of bacteria involved in carbon and nitrogen cycles and possibly those involved in the development of plants. This review identifies the important physicochemical properties of the biochars, which will be able to better guide agricultural producers and industries manufacturing substrates containing peat, in the choice of a biochar favorable to the growth of plants and a more durable agriculture.