『Abstract
　A novel system for organic waste stabilization and reuse, combined with production of nitrate-rich liquid fertilizer was developed by manure digestion followed by volatilization of ammonia-rich gas (originating in manure extract) and its nitrification and recovery. This approach has several advantages, including biowaste stabilization and high recovery (over 60%) of manure N mainly as nitrate which is a better N form for many plants as compared to ammonium as the sole fertilizer N. Moreover, the potential utilization of different wastes as N sources in organic horticulture is possible as well as removal of suspended particles and microorganisms (including pathogens) that might otherwise clog the irrigation system and pose health risks, respectively. In a pilot-scale study, the system yielded several hundred liters of nitrate-rich (ca. 11 g N L^-1) liquid fertilizer using guano as substrate. In a fertilization experiment, lettuce fertigated with the nitrate-rich extract exhibited better growth and quality compared to the common organic practice of fertigation with guano extract. The resulting stabilized biowaste was estimated as “low-risk” according to current guidelines and may be used for liming or land application.

Keywords: Organic agriculture; Fertigation; Biowaste; Ammonia volatilization; Biofiltration; Nitrification』

1. Introduction
2. Materials and methods
　2.1. Liquid organic fertilizer production system
　2.2. Experimental procedure
　2.3. Fertilizer quality assessment
　2.4. Quality of digested manure residue in the EU
　2.5. Statistical analysis
3. Results and discussion
　3.1. The LOFPS and its performance
　3.2. Fertilizer quality assessment
　3.3. Quality of digested manure residue in the EU
4. Discussions
Acknowledgments
References