1. Department of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, CA 94720, USA.
2. Institute for Marine and Atmospheric Research Utrecht, Princetonplein 5, 3584 CC, Utrecht, Netherlands.
3. Department of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.
4. Consiglio per la ricerca e la sperimentazione in agricoltura–Research Center for the Soil-Plant System, Rome, Italy.
5. University of California Cooperative Extension, Bakersfield, CA 93307, USA.