Ecotoxicological effect of a pig manure digested sludge on earthworm (Eisenia fetida) and corn (Zea mays)

Pig Manure Digested Sludge (LDPC) is a byproduct of the treatment of organic waste by anaerobic digestion, implemented in agro-industrial pig farms that, by environmental legislation, must be treated and disposed of without affecting the environment. The ecotoxicological effects of LDPC on the earthworm (Eisenia fetida) and on corn (Zea mays) were evaluated using the indices of LD₅₀ (medium lethal dose), ID₅₀ (Medium inhibition dose), NOEC (No observable effects concentration) and LOEC (Lowest Observable Effect Concentration) indices to determine the level of risk of using LDPC as a soil fertilizer. The values of the LD₅₀ in earthworm and DI₅₀ in corn were 15,50% and 22,60%, respectively, while the evasion test revealed a direct relationship with the presence of LDPC, where from the dose 12,5% is considered a toxic environment for worms. The NOEC and LOEC for the earthworm (mortality and dry weight), and for corn (germination, inhibition, radicle, number of roots, coleoptile, height, number of leaves, wet weight and dry weight) determined values of 15,625% and 18,75%, for worms, and 25% and 50%, for corn, respectively. It is concluded that LDPC can be used as an organic fertilizer if doses that do not exceed the lethal and sublethal effects on the two evaluated species are employed, and if it does not harm the functional and biological quality of the soil.