1. Department of Soil, Water and Environmental Sciences, 429 Shantz Building #38, The University of Arizona, Tucson, Arizona 85721, USA
2. University of Arizona Cooperative Extension, 4341 E. Broadway Rd., Phoenix, AZ 85040, USA
3. Department of Physics, Department of Physics, University of Arizona, 1118 E. Fourth Street, P.O. Box 210081, Tucson, AZ 85721, USA
4. School of Plant Sciences; Marley Building 541H, University of Arizona, Tucson, Arizona 85721, USA