Potential Movement of Pesticides Related to Dissolved Organic Matter from Fertilizer Application on Turf Kun Li*, William A. Torello, J. Scott Ebdon and Baoshan Xing Dept. of Plant and Soil Sciences University of Massachusetts Amherst
What is golfer s expectation? 1. Speed 2. Uniformity
Stress Turfgrass Management Low mowing heights Double cut mowing Use of growth regulators Less nutrient input Rolling of turf Intensive foot traffic Increased pesticide usage
What is Fate of Applied Chemicals on Turf?
Processes that influence the fate of applied pesticides Sorption Degradation Plant uptake Volatilization Runoff Leaching Environmental Impacts
USGA Putting Green Particle Diameter 2.0-3.4 mm 1.0-2.0 mm Recomm. (by weight) < 10%, and < 3% fine gravel 0.5-1.0 mm 0.25-0.50 mm > 60% 0.15-0.25 mm < 20% 0.05-0.15 mm < 5% 0.002-0.05 mm < 5% < 0.002 mm < 3% Very fine sand + silt + clay 10%
Introduction Incorporation organic fertilizers /amendments on turfgrass management. Organic turfgrass management
Introduction Leaching rates of napropamide from sewage sludge amended soil was twice as great as that of none sewage sludge amendments due to enhanced transport by sewage sludge-derived dissolved organic matter (DOM) (Nelson et al., 1998). Petrovic et al. (1996) reported that with addition of peat amendments to sand based putting greens, a 55% increase in fungicide (metalaxyl) leaching occurred compared with sand alone.
Detrimental Effects of DOM Water body contamination Formation of by-products during water treatment DOM acts as precursors in the formation of trihalomethanes (THMs) and other disinfection by-products (DBPs) during the disinfection of municipal water Reduced sorption of pesticides by soil
Reduced Sorption of Pesticides DOM increases solubility of pesticides (Chiou, 1987; Guetzloff and Rice, 1996; Cho et al., 2002). DOM-pesticide interactions and/or competition between DOM molecules and pesticide molecules for sorption sites (Nelson, et al., 1998; Celis et al., 2000; Williams et al., 2002). DOM may serve as a carrier in soil solution that could result in rapid flow of pesticides through soil profiles (Dunnivant et al., 1992)
Objectives To evaluate the potential effect of organic fertilizer derived - DOM on pesticide movement in USGA putting green mix. Overall goal To develop the best management program (BMP) for properly using organic fertilizer on turfgrass management
Fertilizer types Milorganite (6-2-0) (Milwaukee, WI) NatureSafe (8-3-5) (Griffin Industries Inc., Cold Spring, KY ) Sustane (8-2-4) (Natural Fertilizers of American Inc., Cannon Falls, MN) DOM 2.2% 0.75% 0.63%
DOM extraction Solid to solution ratio 1:10. Mixed on shaker for 30 min. at 200 rpm. Centrifuged at 3000 x g for 30 min. Filtered through nitrocellulose filter paper with 0.45 µm pore size. Total organic carbon was analyzed by a Shimadzu TOC-5000A analyzer.
Materials and Methods SORBENT: USGA Sand (SOM, 0.6%) Amherst Soil (Silt loam, SOM, 10%) SORBATE: 14 C labeled and unlabeled Dursban (chlorpyrifos) (O,O-diethyl O-3,5,6-trichloro-2- pyridyl phophorothioate ) and 2,4-D (2,4- dichlorophenoxy acetic acid)
Materials and Methods SOLUTIONS: 0.01 M CaCl2 (background solution) 0.01 M CaCl2 + different concentrations of DOM
Isotherm Construction Batch equilibration; mixed with hematology mixers (Xing and Pignatello 1997). Isotherm fitting model: S = K f C N (Freundlich equation) Log S = Log K f + N Log C
Sorption Isotherm of Chlorpyrifos Sorbed Chlorpyrifos (mg/kg) 100 10 1 0.1 0.01 M CaCl2 0.01 m CaCl2 + 30 mg/l DOC 0.01 M CaCl2 + 60 mg/l DOC 0.01 M CaCl2 + 120 mg/l DOC 0.01 0.0001 0.001 0.01 0.1 1 Solution Concentration (mg/l)
Calculated Parameters of Chlorpyrifos Sorption Isotherm Sorbent Sorption Log K F N r 2 Ce rang (µg L -1 ) K oc (ml g -1 of OC) Ce=0.001 Ce =0.01 Ce = 0.1 mg L -1 mg L -1 mg L -1 USGA Sand 1.42 (0.03)* USGA sand 0.878 + M120 (0.03) USGA sand 0.956 + M60 (0.03) USGA sand 1.03 + M30 (0.02) 0.963 (0.02) 0.975 (0.02) 0.984 (0.04) 0.977 (0.01) 0.995 1.4-380 7075 6498 5967 0.993 4-700 1872 1767 1668 0.993 4-700 2103 2036 2070 0.997 3-600 2563 2482 2109 The values shown in parentheses are 95% confidence intervals, OC = organic carbon.
pure sand pesticide
Chlorpyrifos breakthrough curve for USGA sand Chlorpyrifos Concentration (mg/l) 0.2 0.16 0.12 0.08 0.04 0 0 2 4 6 8 10 Relative Pore Volume (V/Vo) 0.01 M CaCl 2 0.01 M CaCl 2 + 120 mg/l DOC from Milorgantie 0.01 M CaCl 2 + 60 mg/l DOC from NatureSafe
Parameters of column leaching experiment of chlorpyrifos Treatment Total leached out (%) 0.01 M CaCl 2 82.6 (1.0) 0.01 M CaCl 2 93.3 + M120 (4.2) 0.01 M CaCl 2 94.0 + N60 (3.6) Max. conc. (mg L -1 ) Total recovery (%) 0.11 98 0.16 101 0.16 101
Surface tension of different DOM 75 Surface Tension (nn/m) 70 65 60 55 50 45 Milorganite NatureSafe 40 35 1 10 100 1000 10000 Dissolved Organic Carbon Concentration (mg/l)
Diffuse Reflectance Fourier Transform Infrared (DRIFT) spectra of different DOM 2960 2255 1400 1137 741 627 NatureSafe Milorganite Kubelka Munk Unit cm -1 3050 1610 1530 2930 2850 1450 1150 1074 Assignment Aromatic CH Aromatic C=C Aromatic C=C -CH2- -CH2- -CH3 Aliphatic OH Aliphatic C-C 4000 3500 3000 2500 2000 1500 Wavenumbers (cm -1 ) 1000 500
Conclusions DOM extracted from organic fertilizers reduced surface tension with increasing DOM concentration. DOM extracted from organic fertilizers enhanced pesticide leaching in USGA sand, even at DOM concentration as low as 60 mg/l.
Recommendations Do not overapply organic fertilizers/ amendments at one time Do not apply organic fertilizers/amendments immediately after pesticide application
Future studies Field trials to monitor pesticides and DOM in leachates under different golf green management programs. Characterization of DOM from different sources to clarify the effect of DOM on pesticide movement.
Acknowledgments Massachusetts Water Resources Research Center for the financial support.