Wetting Agents and Hydrophobicity of Golf Course Fairways

D.D. Minner and F. Valverde

Purpose:

To determine the effect of experimental wetting agents on soil hydrophobicity.

Methods:

This study was conducted in the summer of 2002 on the second fairway at River Bend Golf Course, Story City, IA. The study area had a segregated mixture of 50% Kentucky bluegrass and 50% perennial ryegrass that was mowed at 0.75 inches and was growing on a Nicollet (fine-loamy, mixed mesic Aquic Hapludoll) soil.

Treatments were applied using a carbon dioxide backpack sprayer equiped with Teejet® XR8002 flat fan nozzles at 30 psi. Each treatment was mixed into 400 ml water and evenly applied onto a 25 sq.ft. plot. This translates to an application volume of 4 gal/1000 sq.ft. Treatments were applied 5 days prior to each sampling date. The study area was sampled for hydrophobicity on August 24 and September 1, 8, 16, and 22, 2002.

Soil hydrophobicity was assessed following the procedure described by Kostka (2000). Two cores of soil from each plot were taken using zero contamination tubes (Clements Associates, Newton Iowa, USA). Cores were removed from tubes and air dried for 2 weeks at 23 ºC. Six droplets (40 μl) of distilled water were applied to each soil core at 6 depths. Starting at depth of 0.5 cm until 6.5 cm, with 1 cm increments. Time was recorded until no free standing water was observed.

Treatments were arranged in a randomized complete block design with 7 treatments and 4 replications. All data were analyzed using the Statistical Analysis System (SAS, Version 6.12) and the Analysis of Variance Procedure (ANOVA).

Results:

Turf quality was evaluated on a scale of 9-1, 9 = best, 6 = lowest acceptable, and 1 = worst quality. Dry spot was evaluated on a percent of the area showing dry spots.

The fairway study area at River Bend Golf Course is normally irrigated during the summer. City water restrictions did not allow for summer irrigation in 2002. The only water applied to the study area came from rainfall or a 0.13-inch hand-watering-in of the entire study area after each treatment date. A 0.25-inch irrigation was applied on the last sampling date because the lack of soil moisture caused the ground to be too hard for sampling. Rainfall totals for May, June, July, August, and September were 4.12, 1.51, 3.10, 4.14, and 0.89 inches, respectively.

First sampling date 8-24-02

Wetting agent treatments had a significant effect on water absorption at the 0 to 2 cm depth. Hydrophobicity was greatest at the surface and decreased deeper in the soil profile. Aqueduct at 4 and 8 oz and ACA at 4 oz provided better soil wetting than the control or ACA 1847. No dry spots were observed on the fairway study area, and turf quality for all plots was 7.5

Second sampling date 9-8-02

Wetting agent treatments showed no significant differences; however, the same trend was observed. Water intake was nearly twice as fast for Aqueduct and ACA 1460 compared to the control and ACA 1847. Treatment rate did not affect hydrophobicity measurements.

Third sampling date 9-8-02:

No treatment differences or trends were present at this sampling date. No dry spots were observed on the fairway study area and turf quality for all plots was 6.5

Forth sampling date 9-16-02:

No treatment differences or trends were present at this sampling date.

Fifth sampling date 9-22-02

Wetting agent treatments had a significant affect on water absorption at the 0 and 2 cm depth. Once again, Aqueduct and ACA1460 reduced hydrophobicity more than the control and ACA 1847. Treatment rate did not affect hydrophobicity measurements. No dry spots were observed on the fairway study area and turf quality for all plots was 8.0.

Conclusions:

Aqueduct and the experimental ACA 1460 reduced hydrophobicity. Treatment rate had no effect on hydrophobicity. There were no visual symptoms of phytotoxicity or dry spot appearance in the study.

Reference:

Kostka, S.J. 2000. Amelioration of water repellency in highly managed soils and the enhancement of turfgrass performance through the systematic application of surfactants. Journal of Hidrology. 231-232: 359-368

Trt #	Treatment	Rate / 1000 ft2	Rate / m2	Rate / plot	Rate / plot + 50% water
1	Control	-	-	-	-
1	Aqueduct	4 oz.	1.25 ml	2.9	5.8
1	Aqueduct	8 oz.	2.5 ml	5.8	11.6
1	ACA1847	2 oz.	0.63 ml	1.45	2.9
1	ACA1847	4 oz.	1.25 ml	2.9	5.8
1	ACA1460	4 oz.	1.25 ml	2.9	5.8
1	ACA1460	8 oz.	2.5 ml	5.8	11.6

First Sampling Date 8/24/02

		Absorption time (seconds)
	Trt	0cm	1cm	2cm	3cm	4cm	5cm	6cm
1	Control	12.75	5.13	0.60	0.30	0.10	0.55	0.05
2	Aqdt 4oz	1.90	0.80	0.20	0.05	0.00	0.00	0.00
3	Aqdt 8oz	3.00	0.90	0.10	0.15	0.05	0.00	0.00
4	ACA1847 2oz	16.55	4.30	1.20	0.70	0.30	0.15	0.10
5	ACA1847 4oz	15.10	4.45	0.80	0.50	0.20	0.20	0.05
6	ACA1460 4oz	3.15	1.20	0.20	0.00	0.00	0.05	0.00
7	ACA1460 8oz	7.70	2.60	0.95	0.35	0.20	0.20	0.10
	Average	8.59	2.77	0.58	0.29	0.12	0.16	0.04
	p	0.0216	0.0487	0.0301	0.4463	0.5447	0.4602	0.6400
	LSD (t 0.05)	10.0480	3.3596	0.7227

Second Sampling Date 9/1/02

		Absorption time (seconds)
	Trt	0cm	1cm	2cm	3cm	4cm	5cm	6cm
1	Control	32.30	10.25	3.35	0.55	1.00	0.15	0.25
2	Aqdt 4oz	12.50	4.60	1.55	1.95	0.75	0.50	1.10
3	Aqdt 8oz	14.55	5.55	3.25	1.65	1.90	1.60	2.75
4	ACA1847 2oz	24.74	7.40	3.50	1.45	0.90	0.35	0.90
5	ACA1847 4oz	27.80	12.20	3.50	1.10	0.80	0.35	0.00
6	ACA1460 4oz	23.20	7.95	5.40	1.35	0.85	0.30	0.25
7	ACA1460 8oz	7.35	5.35	1.80	0.35	0.45	0.30	0.40
	Average	20.35	7.61	3.19	1.20	0.95	0.51	0.81
	p	0.4808	0.7305	0.6224	0.2968	0.7114	0.0382	0.0664
	LSD (t 0.05)						1.4515

Third Sampling Date 9/8/02

		Absorption time (seconds)
	Trt	0cm	1cm	2cm	3cm	4cm	5cm	6cm
1	Control	14.30	5.40	2.80	1.80	0.75	0.95	0.40
2	Aqdt 4oz	19.85	9.25	2.90	2.40	1.00	0.90	0.25
3	Aqdt 8oz	16.55	5.70	2.90	1.35	1.20	1.30	0.75
4	ACA1847 2oz	25.40	7.60	2.75	1.35	0.85	0.50	0.30
5	ACA1847 4oz	18.20	7.70	2.90	1.90	0.80	2.00	1.35
6	ACA1460 4oz	25.55	9.90	2.65	1.35	1.90	0.40	0.35
7	ACA1460 8oz	25.50	9.30	4.00	1.85	1.55	0.60	0.45
	Average	20.76	7.84	2.99	1.71	1.15	0.95	0.55
	p	0.5770	0.1849	0.9285	0.7539	0.3047	0.7538	0.5836
	LSD (t 0.05)

Forth Sampling Date 9/16/02

		Absorption time (seconds)
	Trt	0cm	1cm	2cm	3cm	4cm	5cm	6cm
1	Control	3.05	1.25	0.55	0.00	0.00	0.00	0.00
2	Aqdt 4oz	3.50	1.55	0.50	0.05	0.00	0.10	0.00
3	Aqdt 8oz	2.40	2.30	1.15	0.80	0.05	0.20	0.05
4	ACA1847 2oz	2.65	0.95	0.40	0.15	0.00	0.00	0.00
5	ACA1847 4oz	2.80	2.35	0.90	0.70	0.20	0.00	0.00
6	ACA1460 4oz	4.10	3.25	1.00	0.55	0.15	0.00	0.00
7	ACA1460 8oz	2.35	2.45	0.85	0.50	0.15	0.00	0.00
	Average	2.98	2.01	0.76	0.39	0.08	0.04	0.01
	p	0.8570	0.5389	0.3959	0.0300	0.0503	0.5622	0.4552
	LSD (t 0.05)				0.9217	0.2633

Fifth Sampling Date 9/22/02

		Absorption time (seconds)
	Trt	0cm	1cm	2cm	3cm	4cm	5cm	6cm
1	Control	11.05	3.40	1.35	0.75	0.50	0.35	0.15
2	Aqdt 4oz	6.50	3.35	1.20	1.15	0.70	0.30	0.00
3	Aqdt 8oz	3.21	4.26	1.32	0.53	0.37	0.00	0.00
4	ACA1847 2oz	7.25	3.65	0.85	0.30	0.55	0.10	0.00
5	ACA1847 4oz	7.15	5.20	2.80	1.15	0.70	0.35	0.15
6	ACA1460 4oz	2.65	1.85	0.70	0.80	0.25	0.10	0.00
7	ACA1460 8oz	1.65	0.90	0.60	0.55	0.50	0.05	0.00
	Average	5.64	3.23	1.26	0.75	0.51	0.18	0.04
	p	0.0029	0.0918	0.0006	0.0317	0.3744	0.0810	0.0826
	LSD (t 0.05)	4.0320		0.8334	0.5447

ISU Turfgrass:2003 Turfgrass Report

College of Agriculture

Contents ©1995-2003, ISU Horticulture Department