Global NEST Journal, Vol 9, No 3, pp 195-200, 2007 Copyright© 2007 Global NEST Printed in Greece. All rights reserved AVAILABLE Cd CONTENT OF SALT−AFFECTED AND NORMAL SOILS OF HALASTRA−KALOHORI AREA TH. MATSI 1,∗ E.G. HATZIGIANNAKIS 2 1 Soil Science Laboratory, School of Agriculture Aristotle University of Thessaloniki G.K. ARAMPATZIS 2 54124, Thessaloniki, Greece A.G. PANORAS 2 2 Land Reclamation Institute, NAGREF 57400, Sindos, Greece Received: 02/02/07 *to whom all correspondence should be addressed: Accepted: 02/04/07 e-mail: thmatsi@agro.auth.gr ABSTRACT A survey was conducted in order to evaluate the levels of available (DTPA extractable) Cd in salt affected and normal soils of Halastra−Kalohori area, located in N. Greece. In this area, phosphogypsum (PG) (a byproduct of P fertilizer industry, occasionally enriched with Cd) has been used as amendment for the salt affected soils, for at least 20 years until 2000. The area is about 6300 ha, and 4500 ha were cultivated with rice. Soil samples were collected from 632 points and four depths (0−25, 25−50, 50−75, 75−100 cm), during 2003 and 2004. All soil samples were analyzed for particle size distribution, pH in the paste, electrical conductivity of the saturation extract (EC e ), water soluble Na, Ca and Mg, cation exchange capacity (CEC) and exchangeable Na. The sodium absorption ratio (SAR) and exchangeable sodium percentage (ESP) were calculated. The 632 soils were characterized as salt affected (saline, saline−sodic, sodic) or normal, using the values of EC, SAR and ESP, and pH. In addition, the soil samples collected from the 0−25 and 25−50 cm depths were analyzed for DTPA extractable Cd and Olsen P. All soils were alkaline in reaction. In most of the cases, concentrations of DTPA extractable Cd in the 0−25 cm depth were higher than in the 25−50 cm depth and the mean values differed significantly (p < 0.001). For both depths, concentrations of DTPA extractable Cd were higher for salt affected than normal soils and the mean values within each depth differed significantly (p < 0.001). This could be attributed to the use of PG as soil amendment. In addition, a significant and positive relationship was obtained for DTPA extractable Cd and EC e (r = 0.31, p < 0.001). However, DTPA extractable Cd ranged at levels similar or lower to those reported in the literature for cultivated soils with high P fertilization, in almost all cases. This is something to be expected since 80 % of all soils were sufficient or over−fertilized with P (Olsen P > 15 mg kg −1 ). A significant and positive relationship, obtained for DTPA extractable Cd and Olsen P (r = 0.47, p < 0.001), supported the conclusion that the source of DTPA extractable Cd could also be traced to the long−term P fertilization. Concentrations of DTPA extractable Cd were significantly (p < 0.001) correlated with certain soil properties that affect Cd availability to plants, such as pH (r = −0.26), clay content (r = 0.22) and CEC (r = 0.26). KEYWORDS: Cadmium, phosphogypsum, salt affected soils. INTRODUCTION Cadmium accumulates in soils through weathering of soil parent material, atmospheric deposition from industrial activities, disposal of wastes (sewage sludge, animal manures and industrial byproducts) and soil application of fertilizers (especially phosphates, lime and agrochemicals). Certain soil properties influence soil Cd availability to plants. Soil pH seems to be the major factor that affects Cd availability and in general, Cd becomes more readily