Going Deep: Aerification of Compacted Athletic Fields. Beth Guertal Auburn University, AL

Transcription

1 Going Deep: Aerification of Compacted Athletic Fields Beth Guertal Auburn University, AL

2 Athletic Field Traffic Wear and Tear on Turfgrass

3 Worn turf Soil compaction

4 Soil Compaction where people go

5 Arrrrg.

6 Terms for Physical Soil Properties Porosity Bulk density Hydraulic conductivity Infiltration Water holding capacity

7 Porosity The holes in the soil that are filled with air or water. Pore space is typically around 50% of the total soil volume. We separate pores into two size classes: macropores and micropores.

8 Macropores & Micropores Pore Size Distribution Macropores aid in water drainage, greater in sandy and well-aggregrated soils. Micropores water holding capacity, capillary mvt of water, greater in finetextured soils. Would like about half micro- and half macropores in our distribution of pore sizes.

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10 Bulk Density Mass of soil divided by the volume that soil occupies Bulk density = Weight of the oven dry soil Volume of soil Bulk density increases with compaction, traffic, clay content.

11 bulk density (g cm -3 ) 1.8 Bulk Density as Affected by Traffic Jun-97 Jun Relative Level of Traffic

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13 Hydraulic Conductivity Quantity of water that flows through a column of saturated soil Infiltration Rate at which water enters a soil Infiltration rate time

14 So, what do we want aerification to do? Lessen soil compaction. Improve aeration and drainage. Provide a hole to accommodate topdressing or amendment. Help turf heal and recover. Eliminate layered soils.

15 Questions We Want to Answer about Aerification of Turfgrass How many times a year should we aerify? What tines work best? Does topdressing help? What about soil moisture content? Does adding different amendments help?

16 How Do We Get Answers to Those Questions? In-use hybrid bermudagrass athletic fields (sometimes). Put out replicated treatments over multiple years. Collect quantitative data. Don t irritate the football coaches.

17 Quantitative Data Collection Soil resistance as measured by a penetrometer Soil hardness (impact resistance) Clegg hammer Bulk density Porosity Infiltration rates Saturated hydraulic conductivity

18 Saturated Hydraulic Conductivity Constant Head method (Klute and Dirksen,1986) TGRU 2000 # Aerifications K sat, in hr a 1 11 b

19 Bulk Density as a Function of Treatments Soil bulk density (g cm -3 ) as affected by aerification treatments, TGRU Aerifications bulk density b a a

20 Clegg Impact Soil Tester Measures the hardness of the surface via a weight dropped from an 18 inch height Provides a measure of surface hardness Units are G max with typical values from 30 to 120. (Tiled concrete floor: 1280, tiled floor covered with carpet pad: 260)

21 Rimik CP-20 Cone Penetrometer Most accurate of the field hand-held penetrometers Provides a measure of resistance over depth Takes a while to learn to use well not as easy as it looks

22 5 4.5 y = 0.13x R 2 = 0.17 Lang soil penetrometer (MPa) Rimik soil penetrometer (MPa)

23 Other Quantitative Data Clipping Yield Root length and mass Shoot density Measures of slip Wear recovery Torque reading of established Tifway bermudagrass as affected by N rate, June 2003 Nm lbs N 1,000 ft -2 month

24 Aerification frequency? Two locations: AU Band field and Auburn Turf Unit (TGRU) Tifway hybrid bermudagrass RCB with 4 replications Deep-tine aerification applied at 1, 2 or 4 times a year (Jan, Apr, July, Oct) beginning in October 1998 With and without sand topdressing

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26 Cone resistance as affected by aerification frequency, AU Band Field; 1st year Treatments: = 4 x year = 2 x year = 1 x year Nov 98 July 99 Aug 99

27 Cone resistance as affected by aerification frequency, AU Band Field; 2nd year Treatments: = 4 x year = 2 x year = 1 x year Nov 99 July 00 Aug 00

28 Clegg hammer values as affected by aerification frequency and topdressing, TGRU Date 12/17/00 2/7/00 7/29/00 8/30/00 No. Aerifications a (Oct 99) 71 b (Jan 00) 70 b (July 00) 73 a a (July 99) 80 a (July 99) 79 a (July 00) 72 a a (July 99) 80 a (July 99) 82 a (July 00) 75 a Topdress Y 103 a 76 a 80 a 72 a N 102 a 77 a 79 a 75 a

29 Conclusions Soil resistance unaffected in top inch. Effects of aerification typically lasted ~ 1 month. Aerification effect was shortened if traffic was extreme. Topdressing never affected soil resistance or bulk density.

30 Conclusions - continued Treatments had no significant effect on root mass or thatch Aerification treatments increased hydraulic conductivity significantly for TGRU in 2000 and 2001

31 What Tine is Most Effective? Two locations: AU Football practice field and Auburn Turf Unit (TGRU) Tifway hybrid bermudagrass Aerification applied 4 times per year (May, June, July and August) All plots topdressed with sand after aerification Compaction at the Practice Field natural, roller applied at TGRU

32 Treatments Six treatments: 1) standard depth (4 in.) hollow or 2) solid tine, 3) deep depth (8 in.) hollow or 4) solid tine, and 5) pull behind aerifier. 6) A nonaerified control was also included. These treatments were arranged in a randomized block design of 4 (AU Field) or 5 (TGRU) replications. AU Field 2001 and 2002 TGRU 2002 and 2004 Treatments reapplied in same areas in each year.

33 Aerification units and tines Standard tines Deep depth tines 10 cm long, 1.9 cm diam., hollow or solid 20 cm long, 2.2 cm diam., hollow or solid

34 Pull Behind Aerifier 9 cm long, 1.3 cm diam., hollow

35 Research Methods - Data Soil penetrometer to 24 cm 1 and 4 wk after May, June, July trt for 6 wks after Aug trt Root Mass 2x/year Clegg impact readings 2x/month 1 and 4 wk after May, June, July trt for 6 wks after Aug trt Shoot count 2x/year

36 Soil hardness as measured via Clegg hammer, 2001, AU Practice Field Week after the August, 2001 aerification Trt 1 17 Aug 2 24 Aug 3 31 Aug 4 7 Sept 5 14 Sept 6 21 Sept Clegg reading (g max ) SRH 44 d 50 c 49 b 41 b 39 b 39 c SRS 48 bc 57 b 54 ab 47 a 43 ab 42 c GA60H 46 cd 59 ab 54 ab 46 a 41 ab 42 c GA60S 53 a 63 a 63 a 51 a 44 a 50 a Pull Behind 51 ab 60 ab 61 a 47 a 42 ab 44 bc No aerification 53 a 61 ab 61 a 51 a 45 a 46 ab

37 depth (mm) Soil Resistance Over Depth soil resistance (kpa) wk after June, 2001 treatments AU Practice Field SRH SRS GA60H GA60S Pull behind

38 depth (mm) Soil Resistance Over Depth. soil resistance (kpa) wk after Aug, 2004 treatments TGRU Pull behind No aerification

39 depth (mm) Soil Resistance Over Depth soil resistance (kpa) X SRH No aerification 1 wk after Aug, 2001 treatments X X X X X XY AU Practice Field XY XY XY X 195 X 210 X 225 X 240 X

40 depth (mm) Soil Resistance Over Depth. 4 wk after Aug, 2001 treatments. AU Practice Field Soil resistance (kpa) SRH No Aerification X X X X X XY XY XY X X

41 depth (mm) soil resistance (kpa) Soil Resistance Over Depth. 1 wk after Aug, 2002 treatments. TGRU XY XY XY X GA60H No Aerification

42 depth (mm) Soil Resistance Over Depth. 6 wk after Aug, 2002 treatments soil resistance (kpa) GA60S No aerification X XY XY XY X X 150 AU Practice Field

43 depth (mm) Soil Resistance Over Depth. 6 wk after Aug, 2004 treatments TGRU soil resistance (kpa) X X X X X GA60S No aerification

44 Root Weight and Shoot Density September 7, 2001 AU Practice Field Dry weight of Shoot density roots Trt g core -1 number core -1 SRH 3.9 a c SRS 4.4 a a GA60H 5.3 a bc GA60S 6.0 a 99.8 c Pull Behind 4.8 a a No Aerification 1.6 b bc

45 Conclusions Use of deep depth tines (SRH or SRS) often significantly reduced soil resistance beyond that measured in other aerification treatments and the nonaerified control. This reduction in soil resistance occurred throughout much of the 12 inch sampling depth. Use of hollow tines (regardless of depth) often produced a softer turf surface. Continued use of the GA60S treatment often produced a aerification pan at the bottom of the stroke of the tine.

46 Conclusions The pull behind treatment rarely affected soil softness or resistance beyond that measured in the non-aerified control. Root and shoot density was affected by aerification treatment, but differences were not consistent and differed from year-to-year and location-to-location.

47 Does Adding Different Amendments Help? Many inorganic amendments have appeared in the turf market in last decade. Most of the published research has centered on atconstruction inclusion of the products. Far less work on drill and fill remediation with the products. None of the work has been done on in-use golf course putting greens.

48 Treatments: Amendment Percentage (by vol) Sand 100 Profile (illite) 50 Profile 25 Clinolite (zeolite) 50 Clinolite 25 Axis (diatomaceous earth) 50 Axis 25 None 0 4 replications of each treatment in a RCB design.

49 Installed each June in 2004, 2005 and 2006 in 5 x 10 foot plots. Saugahactee CC, Auburn, AL. Tifdwarf hybrid bermudagrass P. rye overseeding each Fall.

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51 Mehlich Soil-Test Extraction Results after Year 3 Mehlich Extractable soil P, K, Ca and Mg, and soil ph 10 mo. after 3rd incorporation (April, 2007) Trt P K Ca Mg ph lb/a Sand 70 a 50 c 602 ab 68 a 6.0 a Profile (50) 77 a 70 bc 623 ab 77 a 5.9 a Profile (25) 70 a 60 bc 613 ab 71 a 6.0 a Clinolite (50) 76 a 100 a 774 a 77 a 6.1 a Clinolite (25) 80 a 118 a 628 ab 76 a 6.1 a Axis (50) 74 a 56 c 545 b 63 a 5.8 a Axis (25) 77 a 62 bc 593 ab 68 a 5.9 a Nothing 79 a 70 bc 714 ab 81 a 6.0 a

52 Double-ring infiltration measurements, in the field. August 30th, (Two mo. after 2 nd application) Trt in/hr Sand Profile (50) Profile (25) Clinolite (50) Clinolite (25) Axis (50) Axis (25) Nothing 3.0 a 2.4 a 2.8 a 2.2 a 3.4 a 3.4 a 2.2 a 3.4 a

53 Laboratory hydraulic saturated conductivity measurements Trt Sept 04 Nov 05 Mar 05 inches/hour Sand 16 a 18 ab 10 ab Profile (50) 13 a 14 ab 11 ab Profile (25) 11 a 11 b 7 ab Clinolite (50) 12 a 23 ab 12 ab Clinolite (25) 14 a 12 b 14 a Axis (50) 14 a 24 a 13 ab Axis (25) 10 a 15 ab 6 b Nothing 11 a 14 ab 8 ab

54 The Sum Up In heavy traffic more aerification is better. Core aerification did not consistently improve rooting, shoot density or thatch reduction. Topdressing did not affect soil compaction or surface softness. Core aerification does help decrease soil compaction, and (in some cases) soften the turf surface. Hollow cores better than solid. Deeper better if compaction is the real problem. Effects seems to last 4-6 weeks.

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