surfactants as management tools for ameliorating soil water repellency ...
SURFACTANTS AS MANAGEMENT TOOLS FOR AMELIORATING SOIL WATER REPELLENCY IN TURFGRASS SYSTEMS Stanley J. Kostka1, Louis W. Dekker2, Coen J. Ritsema2, John L Cisar3, and Mica K. Franklin1 1
Aquatrols Corporation of America, 1273 Imperial Way, Paulsboro, NJ, 08066, USA 2 Alterra, University of Wageningen, Wageningen, The Netherlands 3 FLREC-IFAS, University of Florida, Ft. Lauderdale, FL, 33314, USA Corresponding author: [email protected]
SUMMARY For over 50 years, soil water repellency (SWR) management strategies have focused on the use of nonionic surfactants, and within the last decade, primarily on ethylene oxide/propylene oxide (EO/PO) block copolymer surfactants, for alleviation of dry spot symptoms to address localised quality and infiltration problems. This review examines the development of structurally modified EO/PO block copolymer surfactants and synergistic co-formulations of alkyl polyglycoside and EO/PO block copolymer surfactants, which have accelerated research on effects on soil hydrological processes in water repellent soils supporting fine turf. An alkyl-modified EO/PO block copolymer surfactant has been shown to mitigate SWR-induced preferential flow, improve soil volumetric water content homogeneity and maximise uptake efficiency, resulting in improved turf quality and density. Other studies suggest that improved efficacy of soildirected fungicides are a consequence of transport process modification. Injection of low levels of synergistic surfactant formulations into irrigation systems have reduced runoff and improved irrigation efficiency under deficit irrigation, while maintaining plant physiological status. INTRODUCTION Water repellency affects diverse soil types under a range of crops and cropping systems worldwide (Wallis & Horne 1992, DeBano 2000, Doerr et al. 2000) and is a commercially important problem in soils supporting highly managed turfgrass stands (Karnok and Tucker 2002a, 2002b). Organic materials originating from fungal hyphae, humic substances, plant root exudates, or decomposing plant material (leaf waxes, clippings, dead roots, thatch) accumulate in interstitial spaces or on the surface of soil particles or aggregates (Doerr 2000 et al. 2000, Hallett et al. 2001). After repeated wetting and drying, soil organic matter undergoes conformational changes to form nonpolar, hydrophobic films (Doerr et al. 2000). Even small quantities of hydrophobic organic matter can influence transport and wetting processes in soils. Mixing 5% (w/w) sand particles with hydrophilic sand induced resistance to spontaneous wetting and 3% (w/w) hydrophobic particles shifted the wetting pattern, resulting in preferential flow (Bauters et al. 2000). At 1% (w/w), sand was wettable, yet flow behaviour was modified (Crist et al. 2004), possibly reflecting subcritical water repellency (Hallett et al. 2004). Once critical moisture content (the nominal volumetric water content below which soil becomes non-wettable; Dekker et al, 2001a, 2001b) is reached, soils shift from wettable to non-wettable, impacting infiltration and unsaturated flow (Dekker et al. 2001b). Soils Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
become difficult to rewet and water bypasses these regions, as in increased runoff and preferential flow through the soil profile (Doerr et al. 2000, Ritsema et al. 2001) resulting in decreased water storage, decreased crop productivity, reduced pesticide and fertiliser efficacy, and reduced irrigation efficiency (Wallis & Horne 1992). Water Repellency in Amenity Turf Considerable SWR research has focused on high value amenity turf (specifically golf course and sports turf) where the problem is manifested as localised dry areas that water does not infiltrate effectively (Miller 2001, Karnok & Tucker 2002a, 2002b, Lyons et al. 2005, Leinauer et al. 2007). On newly constructed golf courses, subcritical water repellency occurs in as little as six months (Schlossberg et al. 2005). Due to the relatively poor water holding capacity of sand-based rootzone mixes, wet-to-dry cycles employed to promote surface firmness between irrigation cycles, or resulting from insufficient irrigation or rainfall during high evaporative demand periods, may result in the development of wilted, discoloured turf patches. Such localised dry spots (LDS) are commonly directly adjacent to visually healthy turf areas. It is usually not until LDS develops, that turf managers commonly notice soil water repellency as an issue (usually occurring within three years of turf establishment). As a consequence, irrigation frequency and volume are often increased, resulting in increased overland flow, more standing water, and increased water use, while turf continues to deteriorate due to drought stress. Management Strategies Traditionally, management strategies have focused on alleviation of LDS symptoms. Maintaining soil moisture above the critical soil water content prevents LDS. However, this strategy conflicts with a range of turfgrass management practices. Soils may be allowed to dry to optimise playing conditions and as a consequence, soils drop below the critical water content and become water repellent. Fertility practices may lead to the accumulation of organic matter and thatch in the upper rootzone which, when dried, becomes water repellent. This problem may be exacerbated by certain new turfgrass cultivars which are prodigious thatch producers. These factors may all be further compounded through cultural strategies that limit aeration and the removal of excessive thatch and organic matter. As thatch accumulates, rootzone moisture management becomes more problematic - when dry, thatch may become water repellent. Conversely when wet, thatch is slow to dry, potential for disease increases, and playing surface performance is compromised. For over 50 years, SWR management has focused on the use of nonionic surfactants for alleviation of dry spot symptoms to address localised quality and infiltration problems (Moore 1981, Rieke 1981). In a little over a decade, nonionic surfactant formulations based on ethylene oxide-propylene oxide (EO/PO) block copolymers, have become the norm for managing SWR and LDS symptoms (Kostka 2005). Based on an extensive two year evaluation supported jointly by the Golf Course Superintendents Association of America and the United States Golf Association, products containing block copolymers were demonstrated to be effective at reducing SWR and alleviating LDS (Throssell 2005). Recently, structurally modified EO/PO block copolymer surfactants, co-formulations of EO/PO block copolymer surfactants and alkyl polyglycoside surfactants with unique properties for modification of flow and transport processes have Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
been described (Kostka 2005, Kostka & Bially 2005, Kostka et al. 2007, Karcher et al. 2006, Oostindie et al. 2006).
Water drop penetration time (in sec)
Water Repellency and LDS Management Two major treatment strategies are employed on tees and greens; monthly versus “longterm” treatments. In a trial conducted in New Jersey, Miller (2001) compared different commercial EO/PO block copolymer-based formulations for longevity of performance in a water repellent sand-based rootzone. Results from that study suggested that "longterm" surfactants (50 L/ha applied one week apart as two 25 L/ha treatments; Product A and Product B) were efficacious in reducing SWR for two to three months postapplication, while surfactants applied monthly at 19 L/ha (Product C) maintained efficacy throughout the four month test period (Fig. 1). Similar results were obtained in an analogous rootzone mix in Ontario, Canada (Lyons et al. 2005). Monthly treatment strategies appeared to deliver surfactant concentrations at adequate levels for longer periods, providing more predictable SWR management. However, in a study conducted in an arid climate, no statistically significant differences between EO/PO block copolymer-based surfactants applied in long-term or monthly treatments were observed (Leinauer et al. 2007). In several cases, applications of certain “long-term” products tended to produce transient declines in turf quality. While only a snapshot of the scope of studies conducted around the world, these three studies illustrate the performance of block copolymer surfactants for ameliorating SWR and LDS.
450 400 350 300 250 200 150 100 50 0
a1 Trt. A application Trt. B application Trt. C application
b b
a a a
c b
May-99
Jun-99
Jul-99
Aug-99
Sep-99
Control
Monthly A - 19 L
Long-Term B - 25 L
Long-Term C - 25 L
1Means
with the same letter on a date are not significantly different according to Duncan’s multiple range test (p = 0.05).
FIG. 1: Effect of “long-term” and monthly surfactant product treatments (L/ha) on persistence of soil water repellency (measured using water drop penetration time test) (New Jersey 1999) (adapted from Miller 2001)
Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
Modification of Critical Water Content Mean soil critical water content was modified in the top 15 cm of the rootzone after monthly applications (1.9 L/ha) of a block copolymer surfactant (Fig. 2) (Dekker et al. 2005). In the top 2.5 cm of the rootzone, untreated soils were wettable until volumetric water content dropped to 18 vol%, while surfactant treated soils were wettable to 11 vol%. At 5 cm, the surfactant-treated soil remained wettable until soil water content reached 6.4 vol%, while the untreated soil became non-wettable at 11 vol%. Similar trends were observed between 7.5 cm and 15 cm, though not to the degree observed in upper regions. Such a shift in critical soil water content enables soils to be dried to achieve firmer playing surfaces, yet ensures that treated soils wet spontaneously when water is applied. Volumetric water content (%) 2
4
6
8
10
12
14
16
18
2 Depth (cm)
4
Water Repellent
6 8 10 12 14
Wettable
16 Surfactant
Untreated
FIG. 2: Soil critical water content curves in an untreated and block copolymer surfactant treated water repellent sand (based on Dekker et al. 2005) Effects on Preferential Flow and Soil Volumetric Water Surfactants have been suggested as a strategy to remediate fingered flow (a form of preferential flow) in water repellent soils (Dekker et al. 2001a), yet until recently, no block copolymer had been demonstrated to achieve this under field conditions. In a two year study in Holland, a water repellent sand fairway receiving monthly treatments with an alkyl-terminated EO/PO block copolymer surfactant (19 L/ha) was compared to a control. Surfactants ameliorated actual SWR to a depth of 25 cm, mitigated preferential flow, and improved soil volumetric water content homogeneity across treated plot surface layers (Fig. 3), resulting in improved turf quality and density (Oostindie et al. 2006). Seasonal water uptake efficiency was 4-fold greater in the surfactant treated soils than in the untreated control. Interactions with Soil Directed Pesticides Evidence supporting improved fungicide rootzone delivery has been demonstrated when an alkyl-terminated EO/PO block copolymer, used in conjunction with a range of fungicides, significantly improved control of fairy ring-causing basidiomycete fungi (Fidanza et al. 2007a, 2007b). The observed increased efficacy suggests that Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
ameliorating preferential flow and soil moisture heterogeneity may have implications in the performance of soil directed pesticides and their leaching management.
FIG. 3: Influence of surfactant treatments on heterogeneity of soil volumetric water content in the top 10 cm of surface layers of a water repellent sand fairway (from Oostindie et al. 2006) Improved Irrigation Efficiency Mitra et al. (2003) and Park et al. (2005) systematically evaluated the effects of low level irrigation applications (0.9 L/ha/mo) of an alkylpolyglycoside-EO/PO block copolymer technology [ACA1848 (Aquatrols Corporation of America, Paulsboro, NJ, USA)] on plant performance, moisture distribution, and irrigation efficiency in different soils, and under conditions of elevated evaporative demand. In a clay loam soil irrigated at 100%, 70%, 30% or 10% evapotranspiration (ET) replacement, Mitra et al. (2003) found that ACA1848 maintained higher soil moisture between irrigation cycles than plots treated with the EO/PO block copolymer alone or an untreated control. In sand, Park et al. (2005) found that ACA1848 maintained higher soil volumetric water content and reduced the irrigation requirement for bermudagrass (Cynodon dactylon X Cynodon transvaalensis). When a water deficit was imposed, turfgrass in surfactant treated plots was at physiological parity with turfgrass growing in control plots irrigated at 100% ET replacement. Based on near-IR and red light reflectance, Park et al. (2005) concluded that plants growing in ACA1848 treated plots under deficit irrigation were in a significantly better physiological state than plants not receiving the surfactant treatment. When comparing the deficit-irrigated plants in the surfactant treated plots to plants in the fully irrigated plots, physiological state was statistically equivalent (p = 0.05). On a loamy sand soil (8% slope) ACA1848 treatment increased infiltration rate, increased time to runoff, and reduced total runoff (Mitra et al. 2006). Subsequent research (Mitra, Cal Poly – Pomona, CA, unpublished) has corroborated improved physiological status (significantly higher (p = 0.05) chlorophyll a, chlorophyll b, total chlorophyll, and the osmoregulating amino acid proline) in Cynodon sp. growing in plots treated with ACA1848. What is the future? Are soil surfactants explicitly tools to mitigate dry spots? Or, are these compounds unique management tools that can be exploited as best management practices to maintain turf quality and optimise irrigation efficiency, conserve water and
Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
improve pesticide efficacy, while reducing the potential for deleterious impacts on water quality? The research highlighted in this review indicates that surfactants applied to water repellent soils can play a demonstrable role in the efficient delivery and conservation of water, while increasing soil-directed pesticide performance and reducing the potential for deleterious impacts to water quality. Research is ongoing to further substantiate these effects, as well as influences on surface playability, nutrient availability and plant health. REFERENCES Bauters TWJ, Steenhuis TS, DiCarlo DA, Neiber JL, Dekker LW, Ritsema CJ, Parlange JI, Havercamp R 2000. Physics of water repellent soils. J. Hydrol. 231-232: 233243. Crist JT, McCarthy JF, Zev1 Y, Baveye P, Throop JA, Steenhuis TS 2004. Pore scale visualization of colloid transport and retention in partially saturated porous media. Vadose Zone J. 3: 444-450. DeBano LF 2000. Water repellency in soils: a historical review. J. Hydrol. 231-232: 432. Dekker LW, Oostindie K, Kostka SJ, Ritsema CJ 2005. Effects of surfactant treatments on the wettability of a water repellent grass-covered dune sand. Aust. J. Soil Res. 43: 383-395. Dekker LW, Oostindie K, Ziogas AK, Ritsema CJ 2001a. The impact of water repellency on soil moisture variability and preferential flow. Int. Turf. Soc. Res. J. 9: 498-505. Dekker LW, Doerr SH, Oostindie K, Ziogas AK, Ritsema CJ 2001b. Water repellency and critical soil water content in a dune sand. Soil Sci. Soc. Am. J. 65: 1667-1674. Doerr SH, Shakesby RA, Walsh RPD 2000. Soil water repellency, its causes, characteristics, and hydro-geomorphological significance. Earth Sci. Rev. 51: 33-65. Fidanza MA, Wong FP, Kostka SJ, McDonald SJ 2007a. Use of a soil surfactant with fungicides for fairy ring disease in turfgrass. Online. J. ASTM Int. http://www.astm.org/cgibin/SoftCart.exe/JOURNALS/JAI/PAGES/JAI100892.h tm?L+mystore+hkfv7982. Fidanza MA, Wong FP, Martin SB, McDonald SJ 2007b. Treating fairy ring with fungicides, new soil surfactant. Golf Course Management 75(5): 121-125. Hallett PD, Ritz K, Wheatley RE 2001. Microbial derived water repellency in golf course soil. Int. Turf. Soc. Res. J. 9: 518-524. Hallett PD, Nunan N, Douglas JT, Young IM 2004. Millimetre-scale spatial variability in soil water sorptivity: scale, surface elevation, and subcritical repellency effects. Soil Sci. Soc. Am. J. 68: 352-358. Karcher D, Miller J, Richardson M, Leinauer B 2006. Irrigation frequency and soil surfactant effects on a sand-based putting green. Int. Conference Biohydrology 2006. Prague. http://147.213.145.2/biohydrology/abstracts/Karcher_S3.doc. Karnok KJ, Tucker KA 2002a. Water repellent soils Part I. Where are we now? Golf Course Management 70(6): 59-62. Karnok, KJ Tucker KA 2002b. Water repellent soils Part II. More questions and answers. Golf Course Management 70(7): 49-52. Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
Kostka SJ 2005. ACA1820: A novel chemistry for rootzone water management in turfgrass systems. Int. Turf. Soc. Res. J. (Annexe) 10: 89-90. Kostka SJ, Bially PT 2005. Synergistic surfactant interactions for enhancement of hydrophilicity in water repellent soils. Int. Turf. Soc. Res. J. 10: 108-114. Kostka SJ, Schuermann G, Franklin M 2007. Alkyl-capped block copolymer surfactants for remediation of soil water repellency and heterogeneous rootzone moisture. Online. J. ASTM Int., in press. Leinauer B, Karcher D, Barrick T, Ikemura Y, Hubble H, Makk J 2007. Water repellency sandy rootzones treated with wetting agents. USGA Turfgrass and Environmental Research Online 6(6): 1-9. http://www.plantmanagementnetwork .org/pub/search/topsearch.asp?page=http://usgatero.msu.edu/v06/n06.pdf. Lyons E, Carey K, Gunn E, Porter A 2005. Field evaluation of experimental surfactant: 2005 season. Guelph Turfgrass Inst. Res. Rep. 19: 27-32. Miller C 2001. Comparing wetting agents: long-term vs. short-term. Golf Course Management. 69(4): 60-64. Mitra S, Kissinger J, Chavez A, Plumb RV, El Awady MN. 2003. Reducing irrigation water on turfgrasses by application of surfactants. J. Misr Soc. Agric. Eng. 11: 181-193. Mitra S, Vis E, Kumar R, Plumb R, Fam M 2006. Wetting agent and cultural practices increase infiltration and reduce runoff and water losses of irrigation water. Biologia, Bratislava. 61/Suppl 19, S353-S357. Moore R 1981. Wetting agents: A tool for influencing water behavior in soil. Golf Course Management. 49: 26-28. Oostindie K, Dekker LW, Wesseling JG, Ritsema CJ 2006. Effects of the surfactant Revolution on soil wetting and turf performance of fairways and greens at the Dutch golf course De Pan. Wageningen, Alterra-special issue 2006. Pp. 95. Park DM, Cisar JL, McDermitt DK, Williams KE, Haydu JJ, Miller WP 2005. Using red and infrared reflectance and visual observation to monitor turf quality and water stress in surfactant-treated Bermudagrass under reduced irrigation. Int. Turf. Soc. Res. J. 10: 115-120. Rieke PE 1981. Wetting agents: Applications vary for different soils. Golf Course Management 49: 26-28. Ritsema CJ, van Dam JC, Dekker LW, Oostindie, K 2001. Principles and modeling of flow and transport in water repellent surface layers, and consequences for management. Int. Turf. Soc. Res. J. 9: 615-624. Schlossberg MJ, McNitt AS, Fidanza MA 2005. Development of water repellency in sand-based root zones. Int. Turf. Soc. Res. J. 10: 1123-1130. Throssell C 2005. GCSAA-USGA wetting agent evaluation. Golf Course Management. 73(4): 52-83. Wallis, MG, Horne, DJ 1992. Soil water repellency. Advances in Soil Science 20: 91146.
Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
Aquatrols Corporation of America, 1273 Imperial Way, Paulsboro, NJ, 08066, USA 2 Alterra, University of Wageningen, Wageningen, The Netherlands 3 FLREC-IFAS, University of Florida, Ft. Lauderdale, FL, 33314, USA Corresponding author: [email protected]
SUMMARY For over 50 years, soil water repellency (SWR) management strategies have focused on the use of nonionic surfactants, and within the last decade, primarily on ethylene oxide/propylene oxide (EO/PO) block copolymer surfactants, for alleviation of dry spot symptoms to address localised quality and infiltration problems. This review examines the development of structurally modified EO/PO block copolymer surfactants and synergistic co-formulations of alkyl polyglycoside and EO/PO block copolymer surfactants, which have accelerated research on effects on soil hydrological processes in water repellent soils supporting fine turf. An alkyl-modified EO/PO block copolymer surfactant has been shown to mitigate SWR-induced preferential flow, improve soil volumetric water content homogeneity and maximise uptake efficiency, resulting in improved turf quality and density. Other studies suggest that improved efficacy of soildirected fungicides are a consequence of transport process modification. Injection of low levels of synergistic surfactant formulations into irrigation systems have reduced runoff and improved irrigation efficiency under deficit irrigation, while maintaining plant physiological status. INTRODUCTION Water repellency affects diverse soil types under a range of crops and cropping systems worldwide (Wallis & Horne 1992, DeBano 2000, Doerr et al. 2000) and is a commercially important problem in soils supporting highly managed turfgrass stands (Karnok and Tucker 2002a, 2002b). Organic materials originating from fungal hyphae, humic substances, plant root exudates, or decomposing plant material (leaf waxes, clippings, dead roots, thatch) accumulate in interstitial spaces or on the surface of soil particles or aggregates (Doerr 2000 et al. 2000, Hallett et al. 2001). After repeated wetting and drying, soil organic matter undergoes conformational changes to form nonpolar, hydrophobic films (Doerr et al. 2000). Even small quantities of hydrophobic organic matter can influence transport and wetting processes in soils. Mixing 5% (w/w) sand particles with hydrophilic sand induced resistance to spontaneous wetting and 3% (w/w) hydrophobic particles shifted the wetting pattern, resulting in preferential flow (Bauters et al. 2000). At 1% (w/w), sand was wettable, yet flow behaviour was modified (Crist et al. 2004), possibly reflecting subcritical water repellency (Hallett et al. 2004). Once critical moisture content (the nominal volumetric water content below which soil becomes non-wettable; Dekker et al, 2001a, 2001b) is reached, soils shift from wettable to non-wettable, impacting infiltration and unsaturated flow (Dekker et al. 2001b). Soils Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
become difficult to rewet and water bypasses these regions, as in increased runoff and preferential flow through the soil profile (Doerr et al. 2000, Ritsema et al. 2001) resulting in decreased water storage, decreased crop productivity, reduced pesticide and fertiliser efficacy, and reduced irrigation efficiency (Wallis & Horne 1992). Water Repellency in Amenity Turf Considerable SWR research has focused on high value amenity turf (specifically golf course and sports turf) where the problem is manifested as localised dry areas that water does not infiltrate effectively (Miller 2001, Karnok & Tucker 2002a, 2002b, Lyons et al. 2005, Leinauer et al. 2007). On newly constructed golf courses, subcritical water repellency occurs in as little as six months (Schlossberg et al. 2005). Due to the relatively poor water holding capacity of sand-based rootzone mixes, wet-to-dry cycles employed to promote surface firmness between irrigation cycles, or resulting from insufficient irrigation or rainfall during high evaporative demand periods, may result in the development of wilted, discoloured turf patches. Such localised dry spots (LDS) are commonly directly adjacent to visually healthy turf areas. It is usually not until LDS develops, that turf managers commonly notice soil water repellency as an issue (usually occurring within three years of turf establishment). As a consequence, irrigation frequency and volume are often increased, resulting in increased overland flow, more standing water, and increased water use, while turf continues to deteriorate due to drought stress. Management Strategies Traditionally, management strategies have focused on alleviation of LDS symptoms. Maintaining soil moisture above the critical soil water content prevents LDS. However, this strategy conflicts with a range of turfgrass management practices. Soils may be allowed to dry to optimise playing conditions and as a consequence, soils drop below the critical water content and become water repellent. Fertility practices may lead to the accumulation of organic matter and thatch in the upper rootzone which, when dried, becomes water repellent. This problem may be exacerbated by certain new turfgrass cultivars which are prodigious thatch producers. These factors may all be further compounded through cultural strategies that limit aeration and the removal of excessive thatch and organic matter. As thatch accumulates, rootzone moisture management becomes more problematic - when dry, thatch may become water repellent. Conversely when wet, thatch is slow to dry, potential for disease increases, and playing surface performance is compromised. For over 50 years, SWR management has focused on the use of nonionic surfactants for alleviation of dry spot symptoms to address localised quality and infiltration problems (Moore 1981, Rieke 1981). In a little over a decade, nonionic surfactant formulations based on ethylene oxide-propylene oxide (EO/PO) block copolymers, have become the norm for managing SWR and LDS symptoms (Kostka 2005). Based on an extensive two year evaluation supported jointly by the Golf Course Superintendents Association of America and the United States Golf Association, products containing block copolymers were demonstrated to be effective at reducing SWR and alleviating LDS (Throssell 2005). Recently, structurally modified EO/PO block copolymer surfactants, co-formulations of EO/PO block copolymer surfactants and alkyl polyglycoside surfactants with unique properties for modification of flow and transport processes have Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
been described (Kostka 2005, Kostka & Bially 2005, Kostka et al. 2007, Karcher et al. 2006, Oostindie et al. 2006).
Water drop penetration time (in sec)
Water Repellency and LDS Management Two major treatment strategies are employed on tees and greens; monthly versus “longterm” treatments. In a trial conducted in New Jersey, Miller (2001) compared different commercial EO/PO block copolymer-based formulations for longevity of performance in a water repellent sand-based rootzone. Results from that study suggested that "longterm" surfactants (50 L/ha applied one week apart as two 25 L/ha treatments; Product A and Product B) were efficacious in reducing SWR for two to three months postapplication, while surfactants applied monthly at 19 L/ha (Product C) maintained efficacy throughout the four month test period (Fig. 1). Similar results were obtained in an analogous rootzone mix in Ontario, Canada (Lyons et al. 2005). Monthly treatment strategies appeared to deliver surfactant concentrations at adequate levels for longer periods, providing more predictable SWR management. However, in a study conducted in an arid climate, no statistically significant differences between EO/PO block copolymer-based surfactants applied in long-term or monthly treatments were observed (Leinauer et al. 2007). In several cases, applications of certain “long-term” products tended to produce transient declines in turf quality. While only a snapshot of the scope of studies conducted around the world, these three studies illustrate the performance of block copolymer surfactants for ameliorating SWR and LDS.
450 400 350 300 250 200 150 100 50 0
a1 Trt. A application Trt. B application Trt. C application
b b
a a a
c b
May-99
Jun-99
Jul-99
Aug-99
Sep-99
Control
Monthly A - 19 L
Long-Term B - 25 L
Long-Term C - 25 L
1Means
with the same letter on a date are not significantly different according to Duncan’s multiple range test (p = 0.05).
FIG. 1: Effect of “long-term” and monthly surfactant product treatments (L/ha) on persistence of soil water repellency (measured using water drop penetration time test) (New Jersey 1999) (adapted from Miller 2001)
Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
Modification of Critical Water Content Mean soil critical water content was modified in the top 15 cm of the rootzone after monthly applications (1.9 L/ha) of a block copolymer surfactant (Fig. 2) (Dekker et al. 2005). In the top 2.5 cm of the rootzone, untreated soils were wettable until volumetric water content dropped to 18 vol%, while surfactant treated soils were wettable to 11 vol%. At 5 cm, the surfactant-treated soil remained wettable until soil water content reached 6.4 vol%, while the untreated soil became non-wettable at 11 vol%. Similar trends were observed between 7.5 cm and 15 cm, though not to the degree observed in upper regions. Such a shift in critical soil water content enables soils to be dried to achieve firmer playing surfaces, yet ensures that treated soils wet spontaneously when water is applied. Volumetric water content (%) 2
4
6
8
10
12
14
16
18
2 Depth (cm)
4
Water Repellent
6 8 10 12 14
Wettable
16 Surfactant
Untreated
FIG. 2: Soil critical water content curves in an untreated and block copolymer surfactant treated water repellent sand (based on Dekker et al. 2005) Effects on Preferential Flow and Soil Volumetric Water Surfactants have been suggested as a strategy to remediate fingered flow (a form of preferential flow) in water repellent soils (Dekker et al. 2001a), yet until recently, no block copolymer had been demonstrated to achieve this under field conditions. In a two year study in Holland, a water repellent sand fairway receiving monthly treatments with an alkyl-terminated EO/PO block copolymer surfactant (19 L/ha) was compared to a control. Surfactants ameliorated actual SWR to a depth of 25 cm, mitigated preferential flow, and improved soil volumetric water content homogeneity across treated plot surface layers (Fig. 3), resulting in improved turf quality and density (Oostindie et al. 2006). Seasonal water uptake efficiency was 4-fold greater in the surfactant treated soils than in the untreated control. Interactions with Soil Directed Pesticides Evidence supporting improved fungicide rootzone delivery has been demonstrated when an alkyl-terminated EO/PO block copolymer, used in conjunction with a range of fungicides, significantly improved control of fairy ring-causing basidiomycete fungi (Fidanza et al. 2007a, 2007b). The observed increased efficacy suggests that Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
ameliorating preferential flow and soil moisture heterogeneity may have implications in the performance of soil directed pesticides and their leaching management.
FIG. 3: Influence of surfactant treatments on heterogeneity of soil volumetric water content in the top 10 cm of surface layers of a water repellent sand fairway (from Oostindie et al. 2006) Improved Irrigation Efficiency Mitra et al. (2003) and Park et al. (2005) systematically evaluated the effects of low level irrigation applications (0.9 L/ha/mo) of an alkylpolyglycoside-EO/PO block copolymer technology [ACA1848 (Aquatrols Corporation of America, Paulsboro, NJ, USA)] on plant performance, moisture distribution, and irrigation efficiency in different soils, and under conditions of elevated evaporative demand. In a clay loam soil irrigated at 100%, 70%, 30% or 10% evapotranspiration (ET) replacement, Mitra et al. (2003) found that ACA1848 maintained higher soil moisture between irrigation cycles than plots treated with the EO/PO block copolymer alone or an untreated control. In sand, Park et al. (2005) found that ACA1848 maintained higher soil volumetric water content and reduced the irrigation requirement for bermudagrass (Cynodon dactylon X Cynodon transvaalensis). When a water deficit was imposed, turfgrass in surfactant treated plots was at physiological parity with turfgrass growing in control plots irrigated at 100% ET replacement. Based on near-IR and red light reflectance, Park et al. (2005) concluded that plants growing in ACA1848 treated plots under deficit irrigation were in a significantly better physiological state than plants not receiving the surfactant treatment. When comparing the deficit-irrigated plants in the surfactant treated plots to plants in the fully irrigated plots, physiological state was statistically equivalent (p = 0.05). On a loamy sand soil (8% slope) ACA1848 treatment increased infiltration rate, increased time to runoff, and reduced total runoff (Mitra et al. 2006). Subsequent research (Mitra, Cal Poly – Pomona, CA, unpublished) has corroborated improved physiological status (significantly higher (p = 0.05) chlorophyll a, chlorophyll b, total chlorophyll, and the osmoregulating amino acid proline) in Cynodon sp. growing in plots treated with ACA1848. What is the future? Are soil surfactants explicitly tools to mitigate dry spots? Or, are these compounds unique management tools that can be exploited as best management practices to maintain turf quality and optimise irrigation efficiency, conserve water and
Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
improve pesticide efficacy, while reducing the potential for deleterious impacts on water quality? The research highlighted in this review indicates that surfactants applied to water repellent soils can play a demonstrable role in the efficient delivery and conservation of water, while increasing soil-directed pesticide performance and reducing the potential for deleterious impacts to water quality. Research is ongoing to further substantiate these effects, as well as influences on surface playability, nutrient availability and plant health. REFERENCES Bauters TWJ, Steenhuis TS, DiCarlo DA, Neiber JL, Dekker LW, Ritsema CJ, Parlange JI, Havercamp R 2000. Physics of water repellent soils. J. Hydrol. 231-232: 233243. Crist JT, McCarthy JF, Zev1 Y, Baveye P, Throop JA, Steenhuis TS 2004. Pore scale visualization of colloid transport and retention in partially saturated porous media. Vadose Zone J. 3: 444-450. DeBano LF 2000. Water repellency in soils: a historical review. J. Hydrol. 231-232: 432. Dekker LW, Oostindie K, Kostka SJ, Ritsema CJ 2005. Effects of surfactant treatments on the wettability of a water repellent grass-covered dune sand. Aust. J. Soil Res. 43: 383-395. Dekker LW, Oostindie K, Ziogas AK, Ritsema CJ 2001a. The impact of water repellency on soil moisture variability and preferential flow. Int. Turf. Soc. Res. J. 9: 498-505. Dekker LW, Doerr SH, Oostindie K, Ziogas AK, Ritsema CJ 2001b. Water repellency and critical soil water content in a dune sand. Soil Sci. Soc. Am. J. 65: 1667-1674. Doerr SH, Shakesby RA, Walsh RPD 2000. Soil water repellency, its causes, characteristics, and hydro-geomorphological significance. Earth Sci. Rev. 51: 33-65. Fidanza MA, Wong FP, Kostka SJ, McDonald SJ 2007a. Use of a soil surfactant with fungicides for fairy ring disease in turfgrass. Online. J. ASTM Int. http://www.astm.org/cgibin/SoftCart.exe/JOURNALS/JAI/PAGES/JAI100892.h tm?L+mystore+hkfv7982. Fidanza MA, Wong FP, Martin SB, McDonald SJ 2007b. Treating fairy ring with fungicides, new soil surfactant. Golf Course Management 75(5): 121-125. Hallett PD, Ritz K, Wheatley RE 2001. Microbial derived water repellency in golf course soil. Int. Turf. Soc. Res. J. 9: 518-524. Hallett PD, Nunan N, Douglas JT, Young IM 2004. Millimetre-scale spatial variability in soil water sorptivity: scale, surface elevation, and subcritical repellency effects. Soil Sci. Soc. Am. J. 68: 352-358. Karcher D, Miller J, Richardson M, Leinauer B 2006. Irrigation frequency and soil surfactant effects on a sand-based putting green. Int. Conference Biohydrology 2006. Prague. http://147.213.145.2/biohydrology/abstracts/Karcher_S3.doc. Karnok KJ, Tucker KA 2002a. Water repellent soils Part I. Where are we now? Golf Course Management 70(6): 59-62. Karnok, KJ Tucker KA 2002b. Water repellent soils Part II. More questions and answers. Golf Course Management 70(7): 49-52. Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
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Kostka SJ 2005. ACA1820: A novel chemistry for rootzone water management in turfgrass systems. Int. Turf. Soc. Res. J. (Annexe) 10: 89-90. Kostka SJ, Bially PT 2005. Synergistic surfactant interactions for enhancement of hydrophilicity in water repellent soils. Int. Turf. Soc. Res. J. 10: 108-114. Kostka SJ, Schuermann G, Franklin M 2007. Alkyl-capped block copolymer surfactants for remediation of soil water repellency and heterogeneous rootzone moisture. Online. J. ASTM Int., in press. Leinauer B, Karcher D, Barrick T, Ikemura Y, Hubble H, Makk J 2007. Water repellency sandy rootzones treated with wetting agents. USGA Turfgrass and Environmental Research Online 6(6): 1-9. http://www.plantmanagementnetwork .org/pub/search/topsearch.asp?page=http://usgatero.msu.edu/v06/n06.pdf. Lyons E, Carey K, Gunn E, Porter A 2005. Field evaluation of experimental surfactant: 2005 season. Guelph Turfgrass Inst. Res. Rep. 19: 27-32. Miller C 2001. Comparing wetting agents: long-term vs. short-term. Golf Course Management. 69(4): 60-64. Mitra S, Kissinger J, Chavez A, Plumb RV, El Awady MN. 2003. Reducing irrigation water on turfgrasses by application of surfactants. J. Misr Soc. Agric. Eng. 11: 181-193. Mitra S, Vis E, Kumar R, Plumb R, Fam M 2006. Wetting agent and cultural practices increase infiltration and reduce runoff and water losses of irrigation water. Biologia, Bratislava. 61/Suppl 19, S353-S357. Moore R 1981. Wetting agents: A tool for influencing water behavior in soil. Golf Course Management. 49: 26-28. Oostindie K, Dekker LW, Wesseling JG, Ritsema CJ 2006. Effects of the surfactant Revolution on soil wetting and turf performance of fairways and greens at the Dutch golf course De Pan. Wageningen, Alterra-special issue 2006. Pp. 95. Park DM, Cisar JL, McDermitt DK, Williams KE, Haydu JJ, Miller WP 2005. Using red and infrared reflectance and visual observation to monitor turf quality and water stress in surfactant-treated Bermudagrass under reduced irrigation. Int. Turf. Soc. Res. J. 10: 115-120. Rieke PE 1981. Wetting agents: Applications vary for different soils. Golf Course Management 49: 26-28. Ritsema CJ, van Dam JC, Dekker LW, Oostindie, K 2001. Principles and modeling of flow and transport in water repellent surface layers, and consequences for management. Int. Turf. Soc. Res. J. 9: 615-624. Schlossberg MJ, McNitt AS, Fidanza MA 2005. Development of water repellency in sand-based root zones. Int. Turf. Soc. Res. J. 10: 1123-1130. Throssell C 2005. GCSAA-USGA wetting agent evaluation. Golf Course Management. 73(4): 52-83. Wallis, MG, Horne, DJ 1992. Soil water repellency. Advances in Soil Science 20: 91146.
Proceedings of the 8th International Symposium on Adjuvants for Agrochemicals (ISAA2007) Publisher: International Society for Agrochemical Adjuvants (ISAA) Editor: RE Gaskin Produced by: Hand Multimedia, Christchurch, New Zealand
6-9 August 2007 Columbus, Ohio, USA ISBN 978-0-473-12388-8
