Turfgrass Science University of Missouri. January 14 th, 2015

Transcription

1 Xi Xiong, Ph. D. and Mica McMillan, M. S. Assistant Professor of Turfgrass Management, University of Missouri; Sr. Research Agronomist, Aquatrols Corp. of America Inc. January 14 th, 2015 Turfgrass Science University of Missouri

2 Soil Water Repellency: Why Should I Care? Is of biological origin Impacts infiltration Increases runoff Impacts turf quality Reduces water stored in the rootzone Reduces irrigation efficiency Causes leaching of pesticides and fertilizers Results in the development of localized dry spots Impacts turf surface playability and function

3 What is wet? Consisting of, containing, covered with, or soaked with liquid (as water). X. Xiong, University of Missouri, 2014.

4 Unstable infiltration ---Preferential flow Wang, Z., Q.J. Wu, L.Wu, C.J. Ritsema, L.W. Dekker, J. Feyen Effects of soil water repellency on infiltration rate and flow instability. J. Hydro. 231:

5 Classic signs of severe drought stress: foot printing, wilting turf turning a darker color and severely stressed, straw-colored turf. The thatch layer and underlying rootzone will probably show signs of hydrophobicity. Sherratt and Street, Ohio State University.

6 Impact of Soil Surfactants Effect on distribution uniformity in soil

7 Water Repellency

8 X. Xiong, University of Missouri, 2014.

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12 Wettability When a drop of liquid placed on a solid surface, it will adhere to it or no, which is the wettability between liquids and solids.

13 WDPT (seconds) 0-5 None Degree of repellency 5-60 Slight Moderate to high 600-3,600 Severe X. Xiong, University of Missouri, >3,600 extreme

14 Chemistry of Water + Hydrogen Bond Covalent Bonds Polar Molecule + - +

15 Cohesion force with which one molecule of water is attracted to another molecule of water

16 Adhesion Physical attraction between water and a solid surface Adhesion Adhesion P O L A R

17 Surface Tension Liquid/Air Interface Non-polar Non-polar Polar

18 Thanks to surface tension: Capillary Action The tendency of liquids to rise up in narrow tubes - capillary action. That s partially the reason that plant can transport water from roots and move up in xylem. Water presence in soil micropores

19 Presence of water = wet? Adhesion: ability of water molecules to stick on a solid surface. Cohesion: attraction of water molecules to themselves. Adhesion > cohesion, wet the surface. Adhesion < cohesion, not wet.

20 Water Repellency Problems begin when soil undergoes wet to dry cycles Non-Polar Polar

21 Water Repellency

22 Water Repellency

23 Water Repellency

24 Water Repellency Surface Architecture

25 Water Repellency Dehydration of Organic Acid Non-polar Organic Organic Hydrophilic Hydrophobic Acid Acid Attachment Attachment Particle Non-polar Coating Polar Polar Non-polar Coating New Organic Acid Attachment

26 Hydrophobicity changes over time X. Xiong, University of Missouri, 2014.

27 X. Xiong, University of Missouri, Fresh sand grain

28 Hydrophobic sand particle with coating (sample with water drop penetration test >2,500 seconds) X. Xiong, University of Missouri, 2014.

29 Reasons Why Water Won t Infiltrate & Penetrate Soils: Physical Problems Chemical Problems Water Repellency/Hydrophobicity Water Movement

30 Reasons Why Water Won t Infiltrate & Penetrate Soils: Physical Problems Solution: Mechanical Aeration deep tining VertiDrain Vertical mowing aeration topdressing Compaction Hardpan Thatch/OM

31 Reasons Why Water Won t Infiltrate & Penetrate Soils: Chemical Problems Solution: Manage Calcium/Salts/Sodium High EC High bicarb High sodium Low Ca

32 Reasons Why Water Won t Infiltrate & Penetrate Soils: Water Repellency / Hydrophobicity Solution: Soil Surfactants Organic acid coatings Soil organic matter Fungal mycelia Low soil water content

33 Sources of Water Repellent Materials m-tyrosine Photo Credit: Tammo Photo Steenhius credit: USDA Slide courtesy of Paul Hallett, Scottish Crop Research Institute

34 Reasons Why Water Won t Infiltrate & Penetrate Soils: Water Movement Solution: Soil Surfactants Water follows path of least resistance preferential flow

35 Wetting agent Definition: any compound that causes a liquid to spread more easily across or penetrate into the surface of a solid by reducing the surface tension of the liquid.

36 What Are Soil Wetting Agents? Polar Non-Polar Amphiphilic

37 All Soil Wetting Agents Are Molecular weight Size Shape Structure NOT The Same How they are constructed determines performance characteristics How they lie on the soil

38 Wetting Agents: How Do They Work? Hydration of Hydrophobic Particle

39 Wetting Agent: Mode of Action Wetting Agent attaches to non-polar sites

40 Wetting Agent: Mode of Action Wetting Agent establishes hydration and drainage providing more balanced moisture and air in the soil.

41 A good soil wetting agent will: To itself To other things

42 Exponential increase of publications related to soil water repellency

43 Dekker, et al Exponential increase of publications related to soil water repellency. Austral. J. of Soil Res. 43:

44 How many different wetting agents are there? Which wetting agent is the best?

45 X. Xiong, University of Missouri, 2014.

46 X. Xiong, University of Missouri, 2013.

47 A B C Untreated X. Xiong, University of Missouri, 2013.

48 Functions of wetting agent Prevent isolated dry spot; Improve water retention; Enhance water infiltration; Improve overall surface uniformity (uniform dew pattern); Improve irrigation efficiency; Enhance pesticide/fertilizer effectiveness; Others?

49 GCSAA/USGA Wetting Agent Evaluation In , four-month experiment. To provide golf course superintendents with unbiased information regarding selected wetting agents so they can make informed use and purchasing decisions. LESCOFlo (LESCO), Primer Select (Aquatrols), Aqueduct (Aquatrols), Cascade Plus (Precision Labs), Tri-Cure (Mitchell Products), Naiad (Naiad), Brilliance (Simplot Partners), Surfside 37 (Montco/Surfside), Respond 2 (Verdicon) and Hydro-Wet (KALO). Turf color, quality, phytotoxicity, hydrophobicity, dew and frost formation, and pest damage.

50 Nine sites including Missouri

51 Results results..are summarized over the next 37 pages. we do not think it is appropriate to draw conclusions from a northern evaluation site for use on a golf course in the South and vice versa. Throssell, C GCSAA-USGA wetting agent evaluation. GCM. April:

52 VWC (%) Function 1: Improve water retention A 13 years old green: WDPT measured in average of 600 seconds or above severe hydrophobic; Slightly increased the volumetric water content in the soil b b b a a a control-75% ET control-100%et Revolution-75% ET Revolution-100% ET Surfside-75% ET Surfside-100% ET X. Xiong, University of Missouri, 2013.

53 Creeping bentgrass growing at 75% of evapotranspiration (ET) replacement at 21 days after wetting agent treatments for: untreated control (A), Tournament Ready (B), Surfside 37 (C), and Revolution (D). X. Xiong, University of Missouri, 2013.

54 Percent N (%) based on dry biomass Percent water (%) abc abc c abc abc bc a ab abc ab a d abc bc bc a bc c ab abc c a abc abc X. Xiong, University of Missouri, 2013.

55 Volumetric water content (%) Function 2: Improve water distribution control Revolution random evaluations per each plot X. Xiong, University of Missouri, 2013.

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57 Function 3: Improve infiltration Song, E., et al., Agron. J. p

58 Song, E., et al., Agron. J. p

59 Complete wetting Incomplete wetting No wetting. θ = 0 θ < 90 θ = 90 θ > 90 θ = 180 A water-repellent soil: initial liquid-solid contact angle > 90.

60 Tap Water Tap Water

61 Song, E., et al., Agron. J. p

62 Figure 1. Infiltration rates into 20 cm sand columns as a function of time for six wetting agents at concentrations of 500, 1000, 3000, or 5000 mg L -1 and a 6.6 cm ponding depth. a = Cascade Plus; b = Hydro-Wet; c = LescoFlo Ultra; d = Revolution; e = Surfside 37; and f = Tournament-Ready. Song, E., et al., Agron. J. p

63 Song, E., et al., Agron. J. p

64 Can we remove the organic coating? If yes, how? Humic acids: soluble in high ph solutions, such as NaOH (Karnok et al., 1993); fulvic acid: soluble in both acidic and basic solutions. Hypothesis : we can remove the organic coating similar to the way we wash grease off our hands. Step 1. Wetting: the wetting agent molecules need to be in contact with the organic coatings; Step 2. Dispersion and/or dissolving: removal of the coating. Step 3. Avoiding re-deposition.

65 Wetting agent A for 4 hours X. Xiong, University of Missouri, 2013.

66 Wetting agent A for 24 hours X. Xiong, University of Missouri, 2013.

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68 ph=7 X. Xiong, University of Missouri, 2013.

69 ph=1 X. Xiong, University of Missouri, 2013.

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71 Coca-Cola X. Xiong, University of Missouri, 2013.

72 % Ring Symptoms Stress Management and Effective Delivery of Pesticides and Fertilizers Percent Fairy Ring Symptoms following 2 applications 25 a 20 ab ab 15 bc 10 d d 5 d 0 Control Insignia Insignia + Revolution Heritage Heritage + Revolution Prostar Prostar + Revolution B. Martin, Clemson University, SC 2005

73 Data collected from golf course greens suggested that wetting agent application does not affect green speed (unpublished data). Playability Surface hardness appears to be unchanged following wetting agent application (Dr. Doug Karcher, University of Arkansas). D. Karcher, University of Arkansas, 2013

74 Summary Water repellency is a surface phenomenon. Wetting agents can improve uniformity of soil moisture, reduce isolated dry spot, increase water use efficiency. Wetting agents may move water down faster, may increase plant available water and increase N/pesticide use efficiency. Remove/displace organic coating (?).

75 Acknowledgements