DONALD L. SPARKS is the Unidel S. Hallock du Pont Chair and Francis Alison Professor at the University of Delaware. He is internationally recognized for his research in the areas of kinetics of biogeochemical processes and surface chemistry of natural materials. His research has focused on fate and transport of trace metals in soil and water, soil remediation, water quality, and carbon sequestration in soils. Dr. Sparks is the author of two previous editions of Environmental Soil Chemistry and more than 350 refereed papers and book chapters. He is fellow of five scientific societies, and he has been the recipient of major awards and lectureships including the Geochemistry Medal from the American Chemical Society, the Liebig Medal from the International Union of Soil Sciences, the Einstein Professorship from the Chinese Academy of Sciences and the Philippe Duchaufour Medal from the European Geosciences Union. Dr. Sparks served as president of the Soil Science Society of America and the International Union of Soil Sciences, has served on advisory committees for several national laboratories and national and international centers and institutes, and served as chair of the U.S. National Academy of Sciences (NAS) Committee for Soil Sciences and other NAS Committees.

• 1. Advances in Host Plant and Rhizobium Genomics to Enhance Symbiotic Nitrogen Fixation in Grain LegumesSangam Dwivedi, Kanwar Sahrawat, Hari Upadhyaya, Alessio Mengoni, Marco Galardini, Marco Bazzicalupo, Emanuele G. Biondi, Mariangela Hungria, Glaciela Kaschuk, Matthew Blair and Rodomiro Ortiz2. Climate Change: Implications for Stakeholders in Genetic Resources and Seed SectorRishi P. Singh, P.V. Vara Prasad, and K. Raja Reddy3. Weedy (Red) Rice: An Emerging Constraint to Global Rice ProductionLewis H. Ziska, David R. Gealy, Nilda Burgos, Ana L. Caicedo, Jonathan Gressel, Amy L. Lawton-Rauh, Luis A. Avila, Giovani Theisen, Jason Norsworthy, Aldo Ferrero, Francesco Vidotto, David E. Johnson, Felipe G. Ferreira, Enio Marchesan, Valmir Menezes, Marc A. Cohn, Steven Linscombe, Luciano Carmona, Rui Tang and Aldo Merotto4. The Challenge of the Urine Patch for Managing Nitrogen in Grazed Pasture Systems Diana R. Selbie, Laura E. Buckthought and Mark A. Shepherd5. Biologically Regulated Nutrient Supply Systems: Compost and Arbuscular Mycorrhizas – a ReviewTimothy R. Cavagnaro