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(T/MF133) Copper dynamics after agronomic pig slurry recycling. González, M.1, de la Torre, A.1, Díez, J.A.2, Aguayo, S.1, Muñoz, M.J.1, 1 2 ABSTRACT- The main heavy metals present in pig slurry are copper and zinc, being copper of special importance due to its capacity of forming both organic and inorganic complexes. This characteristic is of great environmental relevance because it determines its retention capacity in the soil and its mobility. An experimental farm was used, with triplicate control parcels of 100 m2 , parcels with simple and triple- doses application of pig slurry, and one parcel of 20 m2 with a quintuple doses. By means of ceramic candle extraction system at 50 cm deep, seven series of samples were obtained for each parcel during a period of seven months. The samples consisted of soil solution, which was analysed for conductivity, pH, calcium, magnesium and hardness. Copper was analysed using absorption spectrophotometer technique. Daphnia magna was used for the determination of the sample toxicity. The chosen pig slurry was of medium quality, with 5,4 mg/l of Cu, 0.83% of dry matter, corresponding with 71% of organic matter, 1823 mg/l of ammoniac nitrogen and a pH of 7.6. The relation between pig slurry application and copper concentration in the soil solution was studied. The obtained values are under 93 ug/l (except for the quintuple doses) and have a significant heterogeneity, in accordance with the spatial and temporal dynamism and complexity of the soil environment. The obtained copper concentration in the parcel with the quintuple doses, much higher than the values in the other parcels, suggests that two different effects occur after pig slurry application. For the result interpretation, water movement in the soil has been considered. Key words: copper, pig slurry, soil |
