Impacts of Biogas Digestate on Crop Production and the Environment: A Bulgarian Case Study

The water-energy nexus reveals that large amounts of energy is stored in used water and can be used as an energy source. Anaerobic fermentation is an excellent ecological waste treatment and a way of producing low cost electrical and thermal energy. By using digestate resulting from biogas production instead of synthetic fertilizers derived from natural gas, we can save energy, cut consumption of fossil fuels and reduce our carbon footprint. The aim of this study then is to determine the effect of digestate on the yield and quality of crop production as well as its effect on the immediate environment. A ratio of raw materials in biogas, pig manure and vegetable wastes of 70:30 was used on lettuce as an indicator culture. The studies were carried out on two different soil types. Digestate was applied at various percentages, tested with untreated soil as control. The results are encouraging indicating that digestate as a biomass is rich in macro and micronutrients and can be used in agriculture for the improvement of soil fertility.