1. CSIRO Land and Water Private Bag, P.O. Wembley 6014 WA Australia
2. USDA Plant Soil & Nutrition Lab. Tower Rd. Ithaca NY 14853 USA
3. Dep. of Civil and Environmental Engineering, Hollister Hall Cornell University Ithaca NY 14853 USA
4. Dep. of Soil, Crop & Atmospheric Sciences, Bradfield Hall Cornell University Ithaca NY 14853 USA