Production of a biofertilizer from exhausted grape marc waste: agronomic and environmental impact on plant growth

Biochars produced from exhausted grape marc waste were considered a potential source for agriculture biofertilization. Results indicated that the biochar application did not show a significant effect on ryegrass fresh weight increase. The pyrolysis temperature influenced the fresh and dry matter yield since it interferes with phosphorus bioavailability for plant growth. Potassium intakes were positively affected but not statistically significant. The % of soil stable aggregates decreased after 60 days. In the short term, there is no significant effect on soil structural stability. Biochar incorporation led to domination of large macro-aggregates, which are instables compared with small macro-aggregates. A dose of 15 t ha⁻¹ considerably reduced the leached soil and thus improved water retention by changing soil porosity. Soil pH and electric conductivity markedly increased for all treatments after 60 days of incubation. Biochar extract had a significant inhibitory effect on Fusarium oxysporum and Phytophthora sp. The use of exhausted grape marc waste to produce a biochar has shown a good potential for carbon and water sequestration in soil.