1. a USDA, Agricultural Research Service, Hydrology Laboratory , Beltsville, Maryland, 20705, U.S.A
2. b NASA, Goddard Space Flight Center , Greenbelt, Maryland, 20771, U.S.A
3. c National Agricultural Research Center , Yatabe, Tsukuba, 305, Japan
4. d USDA, Agricultural Research Service, Water Conservation Laboratory , Phoenix, Arizona, 85040, U.S.A