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Abstract: The use of a by-product of the fisheries industry (mussel shell) combined with cattle slurry was evaluated as soil amendment, with special attention to the biological component of soil. A wide number of properties related to soil quality were measured: microbial biomass, soil respiration, net N mineralization, dissolved organic carbon, dissolved organic nitrogen, dissolved inorganic nitrogen, dehydrogenase, β-glucosidase, urease and phosphomonoesterase activities. The amendments showed an enhancement of soil biological activity and a decrease of aluminium held in the cation exchange complex. No adverse effects were observed on soil properties. Given that mussel shells are produced in coastal areas as a by-product and have to be managed as a waste and the fertility constraints in the local soils due to their low pH, our research suggest that there is an opportunity for disposing a residue into the soil and improving soil fertility. [Copyright &y& Elsevier]

The biochemical properties of 29 soils under native grassland in a temperate humid zone (Galicia, north-west Spain) and subject to low intensity management (at least during the last 100 years) were determined with the aim of establishing a reference database to allow future comparative studies of the effect of grassland management on soil quality. Several biochemical properties were quantitatively and qualitatively studied. These properties were: labile carbon, microbial biomass carbon, microbial respiration, metabolic quotient, net nitrogen mineralisation and the potential activities of dehydrogenase, catalase, phosphodiesterase, phosphomonoesterase, casein-protease, Baa-protease, urease, cellulase, β-glucosidase, invertase and arylsulphatase. The values of these properties were generally within the ranges of those reported for grassland soils from other parts of the world, but some properties differed both quantitatively and qualitatively from those of forest climax soils in the same area. An equation showing a balance between soil organic matter content and soil biochemical properties was obtained, indicating the existence of a biochemical equilibrium similar to that previously obtained for Galician (north-west Spain) forest climax soils. [ABSTRACT FROM AUTHOR]

The production of organic waste has steadily increased in recent years, with subsequent impact on the environment. The European Union committed to diminish the volume of biodegradable municipal waste disposed of in landfills by 2016–2020. The synthesis of biochar from urban waste and its application to improve soil quality can constitute a novel route for valorization. The aim of this paper was to study the effect of three biochars originated from pyrolysis of the organic fraction of urban waste at two different temperatures (300 °C and 500 °C) and two residence times (1 h and 5 h) on the biochemical properties of an agricultural soil. Soil was amended with biochars at a rate of 8% and incubated for 74 days. A phytotoxicity assay, using garden cress as the test species, was conducted. CO 2 emissions, microbial biomass C and the enzymes dehydrogenase, phosphomonoesterase and β-glucosidase were measured in tested soils. Biochars prepared at 300 °C resulted in lower germination index values, which could partly be ascribed to a higher bioavailability of heavy metals and higher soluble organic matter, while the biochar prepared as 500 °C exhibited a phytostimulant effect. Biochars produced at 300 °C (B300-1 h, B300-5 h) augmented soil CO 2 emissions while there was no effect on microbial respiration in the soil amended with the biochar prepared at 500 °C. Pyrolysis temperature and, for some enzymes, residence time, controlled soil enzymatic activity. [ABSTRACT FROM AUTHOR]