1. The Wyler Dep. of Dryland Agriculture; Jacob Blaustein Inst. for Desert Research, Ben-Gurion Univ. of the Negev; Sede Boqer 84990 Israel
2. Inst. of Soil, Water and Environmental Sciences, Agricultural Research Organization; Gilat Research Center; D.N. Negev 85280 Israel
3. Dep. of Environmental Sciences; Univ. of California-Riverside; Riverside CA 92521
4. Faculty of Agricultural, Food and Environmental Quality Sciences; The Hebrew Univ. of Jerusalem; Rehovot Israel