1 Department Soil Science and Agricultural Chemistry, Engineering Polytechnic School, University of Santiago de Compostela, Lugo, Spain.
2 Soil Science and Agricultural Chemistry, Faculty of Sciences, University of Vigo, Ourense, Spain.
3 Department of Soil and Water Sciences, Faculty of Agriculture, University of Kafrelsheikh, Kafr El-Sheikh, Egypt.
4 Laboratory of Soil- and Groundwater-Management, School of Architecture and Civil Engineering, University of Wuppertal, Institute of Foundation Engineering, Water- and Waste Management, Wuppertal, Germany.