Advances in Agronomy

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. National Comparison of the Total and Sequestered Organic Matter Contents of Conventional and Organic Farm Soils Elham A. Ghabbour, Geoffrey Davies, Tracy Misiewicz, Reem A. Alami, Erin M. Askounis, Nicholas P. Cuozzo, Alexia J. Filice, Jennifer M. Haskell, Andy K. Moy, Alexandra C. Roach and Jessica Shade 2. Harvest Index of Maize (Zea mays L.): Are There Possibilities for Improvement? Birgit W. Hütsch and Sven Schubert 3. Significance and Role of Si in Crop Production Richard J. Haynes 4. Purine-Derived Ureides Under Drought and Salinity Bikash Baral and Maria L. Izaguirre-Mayoral 5. Enhanced Plant Rooting and Crop System Management for Improved N Use Efficiency Ciro A. Rosolem, Karl Ritz, Heitor Cantarella, Marcelo V. Galdos, Malcolm J. Hawkesford, W. Richard Whalley and Sacha J. Mooney