ECOSYSTEM SERVICES PROVIDED BY CONTRASTING GRAZING SYSTEMS IN NORTH FLORIDA By LIZA MARIA GARCIA-JIMENEZ A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2019 © 2019 Liza Maria Garcia-Jimenez To my lovely family ACKNOWLEDGMENTS I would like to thank my advisor Dr. Jose Dubeux for giving me the opportunity to achieve one of my dreams. I am very thankful for his patience, dedication, guidance and friendship. Also, I extend my thanks to all the members of my committee, Dr. Lynn Sollenberger, Dr. Joao Vendramini, Dr. Ellis James, and Dr. Holly Ober, for the time and dedication throughout my project. Thanks for helping me with data analysis and all the valuable inputs for my study. Also, I would like to thank the Agronomy Department for this opportunity, especially to Cynthia Hight for her unconditional help. I give special thanks to the United States Department of Agriculture (USDA) and the North Florida Research and Education Center (NFREC) for the financial support during my PhD. I would like to thank my colleagues and office mates Erick Santos and David Jaramillo, for their invaluable help in the field and with sample analysis. Also, their patience and friendship is greatly appreciated. It was a pleasure to work with these two fine fellow researchers and future colleagues. My research was possible thanks to the help in the field of valuable students and interns. I would like to thank Agustin Lopez, Marina Bueno, Alejandra Gutierrez, Raul Guevara, Camila Sousa, Elijah Conrad, Daci Abreu, Luana Dantas, Pierre Yves, Jose Diogenes, Pedro Sueldo, Jose Rolando, Joyce Patu, Sophia Cattleya, Julie Arnett, Mariana Garcia, Manuel Pena, Caroline Monteiro, Andre Ferraz, Nubia Epifanio, Michell Siqueira, Lucas Miranda, Lautaro Rostoll, Ana Carolina Gomez, Gonzalo Barreneche, Luara Canal, Maria Teresa Davidson, Federico Podversich, Fabio Pinesi, Luana Zagato, Flavia Scarpino van Cleef, Vanessa Longhini, Tessa Shulmeister, and our passionate lab supervisor, science mentor, and friend, Dr. Martin Ruiz-Moreno. I am very thankful for the help and encouragement of the NFREC 4 family, especially to the beef unit crew. I express special gratitude to David Thomas, Tina Gwin and Gina Arnett. I would like to thank my parents Jose Garcia and Gloria Jimenez for their love and guidance and for always inspiring me to learn and keep studying. Special thanks is extended to my mom, my role model, for her unconditional help. I am also grateful for my maternal grandparents, uncles and aunts for their unconditional love, support and for always inspiring me. Finally, I would like to thank my two favorite people in this world, my lovely husband Nicolas DiLorenzo, and my daughter Luciana DiLorenzo. I am very grateful for their help and companionship during my PhD. Thank you for your love, patience and support. 5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES .......................................................................................................... 10 LIST OF FIGURES ........................................................................................................ 12 LIST OF ABBREVIATIONS ........................................................................................... 15 ABSTRACT ................................................................................................................... 16 CHAPTER 1 OVERVIEW ............................................................................................................ 19 2 LITERATURE REVIEW .......................................................................................... 23 Introduction ............................................................................................................. 23 Ecosystem Services from Grasslands .................................................................... 24 Nitrogen Fertilization in Grasslands ........................................................................ 27 Forage-Livestock Systems ...................................................................................... 29 Forage and Animal Performance on Grass Monocultures ...................................... 30 Warm-Season Grass: Bahiagrass .................................................................... 30 Cool-Season Grasses: Oat and Rye ................................................................ 32 Forage and Animal Performance on Legume-Grass Mixtures ................................ 33 Cool-Season Mixtures with Clovers .................................................................. 34 Warm-season Grass Mixture with Rhizoma Perennial Peanut ......................... 35 Application of Stable Isotopes in Grazing Studies .................................................. 37 Nutrient Cycling in Grasslands ................................................................................ 38 Soil Organic Matter (SOM) in Grasslands ........................................................ 39 Biological Nitrogen Fixation (BNF) and Nutrient Cycling .................................. 41 Nutrient Cycling Via Litter and Animal Excreta ................................................. 41 Greenhouse Gas Emissions from Grasslands ........................................................ 43 Enteric Methane Emissions .............................................................................. 45 Legumes and Methane Emissions ................................................................... 47 Importance of Pollinator Insects .............................................................................. 49 Pollination Services from Grasslands ..................................................................... 50 3 FORAGE AND ANIMAL PERFORMANCE IN N-FERTILIZED OR GRASS- LEGUME PASTURE DURING COOL- AND WARM- SEASON ............................. 52 Introduction ............................................................................................................. 52 Materials and Methods............................................................................................ 54 Experimental Site ............................................................................................. 54 Treatments, Experimental Design, and Management ...................................... 55 6 Herbage Responses ............................................................................................... 56 Herbage Mass, Allowance and Accumulation Rate - Cool Season .................. 56 Nutritive Value – Cool-Season ......................................................................... 58 Biological N2 Fixation – Cool-Season ............................................................... 58 Botanical Composition – Cool-Season ............................................................. 59 Herbage Mass, Herbage Allowance and Herbage Accumulation Rate – Warm- Season .............................................................................................. 59 Nutritive Value, Biological N2 Fixation and Botanical Composition – Warm- Season .......................................................................................................... 60 Livestock Performance ........................................................................................... 61 Average Daily Gain, Stocking Rate, and Gain Per Area ................................... 61 Fecal and Blood Samples................................................................................. 61 Statistical Analysis ............................................................................................ 62 Results .................................................................................................................... 63 Herbage Responses – Cool-Season ................................................................ 63 Nutritive Value – Cool-Season ......................................................................... 63 Isotopic Composition and Biological Nitrogen Fixation – Cool-Season ............ 64 Animal Responses – Cool-Season ................................................................... 64 Botanical Composition: Cool- and Warm-Season ............................................ 65 Herbage Responses – Warm-Season .............................................................. 66 Nutritive Value – Warm-Season ....................................................................... 67 Isotopic Composition and Biological Nitrogen Fixation – Warm-Season .......... 67 Animal Responses – Warm-Season ................................................................. 68 Discussion .............................................................................................................. 69 Herbage Responses – Cool-Season ................................................................ 69 Nutritive Value – Cool-Season ......................................................................... 70 Isotopic Composition and Biological Nitrogen Fixation – Cool-Season ............ 72 Animal Responses – Cool-Season ................................................................... 73 Botanical Composition – Cool- and Warm-Season .......................................... 75 Herbage Responses – Warm-Season .............................................................. 76 Nutritive Value – Warm-Season ......................................................................