Evaluation of a phosphorus fertiliser produced from anaerobically digested organic fraction of municipal solid waste

When urban waste is not separately collected its phosphorus content cannot be recovered. The production of phosphorus-based fertilisers from urban waste could generate phosphorus added-value products, reduce environmental impacts from waste disposal and lower the consumption of virgin raw materials in the fertiliser industry. The main objective of this work was to evaluate the short-term agronomic value of a phosphorus fertiliser, which has the same chemical composition and mineralogical structure as struvite, but is artificially produced using phosphorus recovered from the anaerobically digested organic fraction of municipal solid waste (herein referred to as secondary struvite). To evaluate the release of phosphorus forms over time a 30 d incubation experiment was performed. Then the cultivation of rye (Secale cereale L.) was done in pot scale during 45 d to assess the phosphorus phytoavailability and the agronomic potential of secondary struvite, when compared with the commercial mineral fertiliser, single superphosphate. This work contributes to fill a knowledge gap about the effects of this secondary struvite as a source of phosphorus on soil phosphorus forms as well as on phosphorus' soil and plant availability. At the end of the incubation experiment, a similar distribution of phosphorus forms in soil for both secondary struvite and single superphosphate was observed; however, the soil Olsen phosphorus was significantly higher in the soils fertilised using secondary struvite than in those fertilised by single superphosphate, which indicates that secondary struvite provided a higher amount of immediately phytoavailable phosphorus. The shoot biomass production (1.7 g dry-matter kg(-1) soil) and the agronomic efficiency (66 g dry-matter g(-1) phosphorus) were similar for both fertilisers. But the crop's phosphorus uptake and the apparent phosphorus recovery were higher (5.9 mg phosphorus kg(-1) soil and 45%) in the secondary struvite treatment than in the single superphosphate treatment (4.7 mg phosphorus kg(-1) soil and 36%). The results suggest that the secondary struvite can be used as a phosphorus fertiliser and lower rates of the secondary struvite are required to achieve the same agronomic efficiency as the single superphosphate. (c) 2019 Elsevier Ltd. All rights reserved.