Liquid Fraction of Digestate as good as Chemical Fertiliser? - Observations from a Three-Year Field Experiment

摘要

To safeguard water quality and protect waters against agricultural pressures, a comprehensive framework of EU legislation has been introduced (ex. Nitrate Directive 91/676/EC and Water Framework Directive 2000/60/EU) and translated to member states action plans. In Flanders (Belgium), restrictions are imposed on both nitrogen and phosphate rates coming from livestock manure. While the maximum allowed nitrogen rate is 170 kg N/ha/year (European Commission, 1991), phosphate application rates are quitelower, ranging from 40 to 70-90 kg P205/ha/year for P-saturated area and areas with a low phosphate binding capacity (Amery and Schoumans, 2014), respectively. This makes it impossible to fill the maximum allowed rate for nitrogen entirely by livestock manure. Therefore, despite of existing manure surpluses, expensive and energy consuming synthetic fertilizers are utilized to meet crop nutrient requirements. Nitrogen recovery and thus valorization of remaining N in these manure surpluses could however decrease the need for synthetic fertilizers.