Turf-type tall fescue roots GypsumControl 0-3.5 ” 3.6-7 ” 7-11 ” Soil chemical or soil physical problem?
Treatment Options??? Lime –Agricultural grade limestone is an effective ameliorant of soil acidity –Commonly incorporated at establishment for production of cotton, soybean, corn, peanuts, etc. –INCORPORATE is the key word, effective treatment of soil acidity with lime requires tillage into the soil profile
They don’t. Turfgrasses are perennial in nature and establishment is not only uncommon, but dreaded! So how can managers ameliorate the effects of acidity without plowing the lawn?
Gypsum Many attributes: –More soluble than agricultural lime –Doesn’t require tillage or coring –Doesn’t raise pH of the surface soil This can cause soil structure and turf disease problems –Provides sulfate (SO 4 ), the plant essential nutrient form of sulfur
Tall fescue root growth column study a a a bb bb cc
Greenhouse Experiment Objectives 1. Construct columns which represent soil profiles indigenous to the SE US. 2. Analyze leachate to confirm calcium sulfate penetration of subsoil, displacement of Al, and/or other soil chemistry alterations. 3. Use installed instrumentation to monitor water extraction from acidic subsoil by roots, by depth. 4. Simulate drought periods repetitively; mimicking rain patterns, while promoting deep rooting in columns 5. Analyze columns to assess root architecture and calcium saturation of CEC by soil depth.
Treatments (5): Synthetic/FGD Gypsum (Southern Co.) Tech. Grade Gypsum (CaSO 42H 2 O) Calcium Chloride (CaCl 22H 2 O) Calcitic Lime (100% CCE) Control 90 columns total; 60 Bermudagrass (‘Princess’ or ‘Sultan’) and 30 turf-type Tall Fescue ‘Rebel’ Half of each instrumented for real-time soil moisture, three replications of six Experimental Design
The Southern Co. SynGyp, is generated by a ‘wet’ spray-dryer scrubbing process, and contains 23.3% Ca by mass (+/- 0.65), and has a calcium carbonate equivalency of 2.7% (+/- 0.14). Trace element and heavy metal analysis show few impurities Experimental Design
The Southern Co. SynGyp is 23.3% Ca by mass (+/- 0.65), and has a calcium carbonate equivalency of 2.7% (+/- 0.14). Trace element and heavy metal analysis show few impurities Application Rates Treatmentlbs/Acre (Ca) Lime 4,332 (1,735) FGD and TG Gypsum13,796 (3,224) CaCl 2 11,825 (3,224) Experimental Design
The Southern Co. SynGyp is 23.3% Ca by mass (+/- 0.65), and has a calcium carbonate equivalency of 2.7% (+/- 0.14). Trace element and heavy metal analysis show few impurities Application Rates Treatment Mg/ha (Ca) Lime 4.86 (1.94) FGD and TG Gypsum 15.46 (3.61) CaCl 2 13.25 (3.61) Experimental Design
Cultural Methods TF columns mowed every 9±3 days @ 3” height No signs/symptoms of pest activity observed over the 2-year study, hence no pesticides were applied (tall fescue is good like that) When >half the TF columns showed stunted growth & leaf firing, all were irrigated with 4” in 1” pulses over 24 hours (every 20-35 days) Post-estab: ¼ lb N & K 2 O / 1000 ft 2 / month
Cultural Methods Bermudagrass columns mowed every 7±3 days @ 1.4” height Insect activity was chemically controlled when necessary When >half the bermuda columns showed stunted growth/dormancy, all were irrigated with 4” in 1” pulses over 24 hours (every 30-50 days) Post-estab: ¾ lb N & K 2 O / 1000 ft 2 / month
Tall Fescue root length in the 38 –62 soil depths
Greenhouse Study Summary Gypsum trts effectively penetrated 60 cm of clay soil 1 year after a ~7 ton/A application Differences between mined & synthetic gyp were slight, allowing pooled analysis Benefits to TF were stark: enhanced growth, total & deep water uptake, deep roots, and leaf S; compared to both Lime and Con trts (with no resulting base cation deficiencies) Benefits to bermudagrass include: enhanced growth & color response under drought conditions (deeper roots?)
Control Gypsum Treatment Effect of Gypsum Addition on Root Growth at East Lake Golf Club Gypsum treatment = 4 tons/acre, April 11, 2005 Samples collected May 19, 2006
Summary Large (>5 ton) gypsum apps to turfgrass did not induce salt or phytotoxic injury More significant advantages of gypsum applications are associated with turfgrasses poorly adapted to weathered, acid soils Continuing turfgrass root analysis should demonstrate advantages of increased Ca:Al ratio in acid subsoils Leaf Ca and S were not always correlated to root length and water use benefits
Acknowledgements Lamar Larrimore, Southern Company Dr. Bill Miller, University of Georgia Dr. John Kruse, University of Georgia Dr. Malcom Sumner, University of Georgia Michael Wolfe, Southern Company