EVALUATION OF WATER-USE IN TURFGRASS Except where reference is made to the work of others, the work described in this dissertation is my own or was done in collaboration with my advisory committee. This dissertation does not include proprietary or classified information. ____________________________________ Leonard Jonah Mwai Githinji Certificate of Approval: Robert H. Walker Jacob H. Dane, Chair Professor Professor Agronomy and Soils Agronomy and Soils Joey N. Shaw David Y. Han Professor Associate Professor Agronomy and Soils Agronomy and Soils George T. Flowers Interim Dean Graduate School EVALUATION OF WATER-USE IN TURFGRASS Leonard Jonah Mwai Githinji A Dissertation Submitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Auburn, Alabama December 17, 2007 EVALUATION OF WATER-USE IN TURFGRASS Leonard Jonah Mwai Githinji Permission is granted to Auburn University to make copies of this dissertation at its discretion, upon request of individuals or institutions and at their expense. The author reserves all publication rights. Signature of Author Date of Graduation iii VITA Leonard Jonah Mwai Githinji was born and raised in Central Province, Kenya. He received his Bachelor of Science in Agriculture (Honors) from the University of Nairobi, Kenya. This was followed by several years of professional career as an Agronomist (Anicare Limited), Land and Water Management staff (University of Nairobi) and Agricultural Extension Specialist (Ministry of Agriculture). In May-July 1998, he received post-graduate training in Agricultural Meteorology (Bet Dagan Institute, Tel Aviv, Israel). In September 2001, he enrolled in Graduate School at Ghent University, Belgium for Master of Science in Physical Land Resources (Management of Physical Land Resources Option), where he graduated with Great Distinction. In January 2004, he enrolled in Ph.D. Agronomy and Soils program at Auburn University, Auburn, Alabama. Leonard is married to Eunice and has two children, Janet and Claire. iv DISSERTATION ABSTRACT EVALUATION OF WATER-USE IN TURFGRASS Leonard Jonah Mwai Githinji Doctor of Philosophy, December 17, 2007 (M.S., Ghent University, Belgium, 2003) (B.S., University of Nairobi, Kenya, 1994) 170 Typed Pages Directed by Jacob H. Dane and Robert H. Walker This dissertation examined the response of four hybrid bluegrasses [Texas bluegrass (Poa arachnifera Torr.) × Kentucky bluegrass (Poa pratensis L.)], HB 129 (‘Thermal Blue’), HB 130, HB 328 and HB 329 (‘Dura Blue’) and two tall fescue cultivars (Festuca arundinacea Schreb.), ‘Green Keeper’ and ‘Kentucky 31’, to varying irrigation replenishments. Field experiments were conducted at the Turfgrass Research Facility, Auburn University, AL, from June through September 2005 and a similar period in 2006. Three irrigation treatments were applied based on potential evapotranspiration (ET), viz., 100 % ET, 80 % ET and 60 % ET replacements. The experimental design was a 6 by 6 Latin square with six replicates of each treatment combination within an irrigation block. Tensiometers were installed at 7.5-, 15- and 30-cm depths in the middle blocks of each plot, readings were recorded daily and the values were used to calculate the matric head, water content and water-use values. Turf color quality, root length v density and root dry mass of hybrid bluegrasses and the tall fescue cultivars were evaluated. The research showed that the hybrid bluegrasses used less water compared to the tall fescue cultivars. The ranking based on root length density and turf color quality was: HB 329 (best) > HB 130 > HB 328 > HB 129 > Kentucky 31 > Green Keeper. Physical and hydraulic properties of inorganic amendments used in turfgrass root zones were evaluated. The objectives of this study were i) to evaluate and compare the physical and hydraulic properties of un-amended sand (100% sand) and 7 commercially available inorganic amendments used in sand-based root zones, viz., zeolites (Clinolite and Ecolite), calcined diatomaceous earth (Isolite and Axis) and calcined clays (Moltan plus, Profile, and Pro’s Choice), and ii) to evaluate the physical and hydraulic properties of amendment-sand mixtures (15% amendment with 85% sand v/v). The properties analyzed were bulk density, particle density, porosity, particle size distribution, saturated hydraulic conductivity, water retention and available water. All the amendments and amendment-sand mixtures exhibited higher porosity, water retention and available water compared to 100% sand. The values were highest for the calcined diatomaceous earths. A numerical model was applied to simulate soil water movement with root water uptake for a scenario with amendments (15% amendment plus 85% sand v/v), and without amendment incorporation (100% sand). The simulation results showed reduced surface dryness, higher volumetric water content and storage, and higher initial root water uptake rate for the root zones modified with amendments. The highest simulated water storage was observed for root zones modified with calcined diatomaceous earths, especially Axis amendment. vi ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my research advisors, Dr. Jacob H. Dane and Dr. Robert H. Walker, for their guidance and support during my graduate program at Auburn University. I extend my thanks to the other committee members Dr. Joey N. Shaw and Dr. David Y. Han. I wish to convey my appreciation to Mr. Jim Harris, the Turfgrass Research Facility superintendent who was invaluable during the irrigation experiment, Dr. Laurent Bahaminyakamwe for assisting during data collection, Mr. Jason Belcher in turf root samples collection, Mr. Bill Bryce who assisted during the root scanning, and Dr. Steve Prior for allowing me to use the root length scanner at the USDA. Finally, I offer my deepest gratitude to my wife Eunice and our two daughters Janet and Claire for their unconditional love and support. vii Style manual used: Handbook and Style Manual of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America Computer software used: Microsoft Word v. 2003; Microsoft Excel v. 2003; Hydrus 1-D; SigmaPlot v. 9.0; SigmaScan Pro v. 5.0; SAS System for Windows v. 9.13 viii TABLE OF CONTENTS LIST OF TABLES……………………………………………………………..…..…......xi LIST OF FIGURES………………………………………....……………...…………...xiii I. LITERATURE REVIEW................................................................................................ 1 Introduction......................................................................................................................... 1 Research Justification ....................................................................................................... 19 General Objectives............................................................................................................ 20 References......................................................................................................................... 21 II. EVALUATION OF WATER USE PATTERNS OF TALL FESCUE AND HYBRID BLUEGRASS CULTIVARS ........................................................................... 29 Abstract............................................................................................................................. 29 Introduction....................................................................................................................... 30 Materials and Methods...................................................................................................... 37 Results and Discussions.................................................................................................... 43 Summary and Conclusions ............................................................................................... 52 References......................................................................................................................... 53 III. EVALUATION OF TURF COLOR QUALITY, ROOT LENGTH DENSITY AND ROOT MASS OF HYBRID BLUEGRASS AND TALL FESCUE UNDER IRRIGATION SCHEDULING......................................................................................... 77 Abstract............................................................................................................................. 77 Introduction....................................................................................................................... 78 Materials and Methods...................................................................................................... 84 Results and Discussions.................................................................................................... 87 Summary and Conclusions ............................................................................................... 92 References......................................................................................................................... 94 IV. EVALUATION OF PHYSICAL AND HYDRAULIC PROPERTIES OF INORGANIC AMENDMENTS USED IN TURFGRASS ROOT ZONES .................. 105 Abstract........................................................................................................................... 105 Introduction..................................................................................................................... 106 Materials and Methods.................................................................................................... 109 Results and Discussions.................................................................................................