Biol Fertil Soils (2003) 38:327–332 DOI 10.1007/s00374-003-0660-z SHORT COMMUNICATION Maria Antonietta Rao · Filomena Sannino · Giulia Nocerino · Edoardo Puglisi · Liliana Gianfreda Effect of air-drying treatment on enzymatic activities of soils affected by anthropogenic activities Received: 28 January 2003 / Accepted: 24 June 2003 / Published online: 17 July 2003  Springer-Verlag 2003 Abstract The influence of air-drying on dehydrogenase, invertase, b-glucosidase, urease, phosphatase, arylsul- phatase and phenoloxidase activities was measured in three soils affected by anthropogenic activities and in control soils sampled from neighbouring areas. The air- drying changed enzyme activity, but the behaviour was neither site-specific nor enzyme-sensitive. Canonical discriminant analysis of enzymatic activities of both moist fresh and air-dried samples was able to discriminate between altered and unaltered soils irrespective of the site. Numerical alteration indices were developed as a linear function of the seven enzyme activities and the one obtained from fresh sample data was more successful. Air-drying apparently alters in unpredictable ways en- zyme activities of soils, which could lead to misinterpre- tation of results. Keywords Soil enzymes · Air-dried soils · Soil quality indicators · Canonical discriminant analysis Introduction Several physical, chemical and biological properties, including enzyme activities, have been proposed as indicators of soil quality and health (Dick 1994; 1997, Dick et al. 1996; Nannipieri 1994). Enzyme activities may reflect the overall microbial activity of soil, and as such are sensitive to variations induced by natural and anthropogenic factors (Gianfreda and Bollag 1996). Enzyme activities can be also used as biomarkers of degradation and (bio)remediation processes (Tate 1995; Leiros et al. 1999; Trasar-Cepeda et al. 2000; Margesin et al. 2000; Pascual et al. 2000). However, it is important to determine a number of enzyme activities, representative of a wide range of microbial functions, to reliably represent the soil system (Nannipieri 1994; Nanniperi et al. 2002). If enzyme activities of soil are to be used as indicators of soil quality, standard assay procedures and pre- treatments need to be defined (Dick 1994). For physical and chemical properties of soil, the conditions adopted for soil treatment and storage prior to analysis are not always crucial. In contrast, soil pre-treatment and storage may have a major bearing on the relevance of the results, when monitoring biochemical activities (Brohon et al. 1999). In this regard there are contradictory suggestions. A short storage period (at the most 10–15 days) of field-moist soils at 4C has been suggested as the most appropriate for a reliable determination of the majority of soil enzymatic activities (Alef and Nanniperi 1995; Gianfreda and Bollag 1996; Tabatabai and Dick 2002). When it is not possible to process and analyse samples within this time interval, soil has to be stored under conditions that assure minimum changes of the measured properties. Storage of soils in an air-dried state has been proposed to be a satisfactory pre-treatment for soils under such conditions (Burns 1978; Alef and Nannipieri 1995; Gianfreda and Bollag 1996; Tabatabai and Dick 2002). The literature on the effect of soil air-drying on enzyme activities is extensive (Ladd 1985; Gianfreda and Bollag 1996). Several papers deal with the response of a single enzyme activity under a particular agricultural management, vegetation cover or pollutant to air-drying of soil. However, only few, if any, reports deal with the behaviour of a set of enzyme activities upon air-drying of soils subjected to different kinds of anthropogenic perturbations. The present study was undertaken to evaluate whether air-drying might be a useful procedure for handling soils M. A. Rao · F. Sannino · G. Nocerino · L. Gianfreda ( ) ) Dipartimento di Scienze del Suolo della Pianta e dell’Ambiente, Sezione Scienze Chimico-Agrarie, Università di Napoli Federico II, Via Università 100, 80055 Napoli, Portici, Italy e-mail: liliana.gianfreda@unina.it Tel.: +39-81-2539179 Fax: +39-81-2539186 E. Puglisi Istituto di Chimica agraria e ambientale, Facoltà di Agraria dell’Università Cattolica del Sacro Cuore, Sede di Piacenza, Italy