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Increasing N use efficiency is an important strategy to intensify sustainable agriculture, optimize nutrient use, and reduce N loss to the environment via different routes. Owing to its physicochemical properties, biochar can be used as an additive to produce biochar-based fertilizers (BFs) with increased efficiency. We investigated N availability and ammonia loss from 17 BFs (3%–38% N). N availability and release from BFs were evaluated by water extraction experiments and soil column leaching. BFs (5%–10% N) had an average of 64% solubilized N after five extractions, whereas urea had 98% solubilized N. However, BFs produced with urea released N more slowly in soil, with the release rate 60% less than that of urea. Ammonia volatilization was evaluated using a 22-d experiment, where N was applied to soil surface (pH = 4.4). We compared urea, BF granulated with urea, and BF produced by coating urea granules with acidified or unacidified biochar. Compared to urea, biochar-based fertilizers granulated with urea and urea granules coated with acidified biochar significantly reduced (t-test at 5%) ammonia volatilization by 14%. The results demonstrated the potential of BFs as enhanced efficiency fertilizers. Therefore, BFs might be a good option to mitigate N loss. [ABSTRACT FROM AUTHOR]