Evaluation of safety and quality of final compost

The fine fraction resulting from the sieving (≤12 mm) of the two batches of compost was sent to an independent accredited laboratory (SADEF, France) to analyze the safety and agronomic quality according to the NF U44-051:2006 standard dedicated to organic soil improvers. The safety requirements cover the determination and quantification of inert materials and impurities (XPU 44-164:2004), pathogen microorganisms as viable helminth eggs (XP X33-017:2004) and Salmonella (NF EN ISO 6579:2002), HAP trace organic compounds (XP X 33-012:2000) and trace elements (NF EN 13650:2002, NF EN ISO 17294-2:2016). The agronomic assessment of the two composts covers the determination of total solid, organic matter, organic carbon, total nitrogen C/N ratio, pH, density, phosphorus, potassium, calcium, magnesium, total sulphur content according to standardized methods (NF EN 13040:2007, NF EN 13039:2011, NF EN 13037:2012, NF EN 13654-2:2002, NF EN ISO 17294-2:2016). A phytotoxicity test was carried out on both compost batches (NF U44-167:2016) to assess the risk of inhibiting the emergence and growth of two higher plants (barley, Hordeum vulgare, variety Etincel and watercress, Lepidium sativum, type Alénois). The acute toxicity test on earthworms (Eisenia fetida) was carried out in accordance with standard NF ISO 11268-1:2012. The immobilization test of microcrustaceans was carried out on Daphnia magma (ISO 6341:2012 using an eluate of the two composts obtained with a liquid/solid mass ratio of 10 (calculated as dry matter equivalent) as described in the leaching protocol of standard EN 12457-2:2002.