1. Agriculture and Agri-Food Canada; Lethbridge Research Centre; P.O. Box 3000 Lethbridge AB Canada T1J 4B1
2. Dep. of Soil Science; Univ. of Manitoba; Winnipeg MB R3T 2N2 Canada
3. Dep. of Soil Science, Faculty of Agriculture; Univ. of Peradeniya; Sri Lanka