title: Effect of water deficit on microbial characteristics in soil amended with sewage sludge or inorganic fertilizer under laboratory conditions.
abstract: The potential impact of different types of organic (sewage sludge) or inorganic (mineral fertilizer) amendments to a basic soil was investigated under dry conditions. A soil incubation experiment was carried out over 64 days; there were two fertility treatments: sewage sludge (SS) (140 t ha(-1)), mineral fertilizer (M) and an unamended control (C). Two levels of irrigation were imposed: (1) well-watered, kept at 60% of its water holding capacity, and (2) water-deficit at 6%. Available N-NO3-, N-NH4+ and P, and electrical conductivity (EC) increased in SS and M-treated soils. Under well-watered conditions activities of some enzymes (protease-BAA, phosphatase and beta-glucosidase), and microbiological properties (microbial biomass carbon, basal respiration and dehydrogenase activity) were stimulated in SS-treated soils. Under water-deficit conditions, protease-BAA, phosphatase and beta-glucosidase activities, and basal respiration were more reduced in SS than in C and M. Results showed that under severe dry conditions, soil microbial activity always remained higher in organic amended soils than when mineral fertilizer was added.
authors.affiliation: Departamento de Fisiología Vegetal, Universidad de Navarra, Irunlarrea s/n, 31008 Pamplona, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Pascual
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Antolín
authors.forename: Carlos
authors.initials: C
authors.lastname: García
authors.forename: Alfredo
authors.initials: A
authors.lastname: Polo
authors.forename: Manuel
authors.initials: M
authors.lastname: Sánchez-Díaz
mesh_terms: D000641:Ammonia / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis; D018533:Biomass; D005308:Fertilizers / Q000032:analysis*; D009566:Nitrates / Q000032:analysis; D010758:Phosphorus / Q000737:chemistry; D012722:Sewage / Q000032:analysis*; D012988:Soil Microbiology; D013997:Time Factors; D014867:Water / Q000032:analysis*
chemical_list: D001426:Bacterial Proteins; D005308:Fertilizers; D009566:Nitrates; D012722:Sewage; D014867:Water; D010758:Phosphorus; D000641:Ammonia