1998 Iowa Turfgrass Research Report
Creeping Bentgrass Establishment on Sand Greens
Michael B. Faust, Nick E. Christians, and Barbara R. Bingaman
This creeping bentgrass establishment trial was initiated 1 Sept. 1996 at the Iowa State University Horticulture Research Station. The study was conducted to observe the development of creeping bentgrass from seed grown in a sand-based golf course green.
Sand has become a popular growing medium for golf course greens. The popularity of sand is due to its physical characteristics. Sand-based greens are more resistant to heavy compaction and provide increased water infiltration through the subsurface of the green. However, high sand content greens have drawbacks. Greens constructed of high sand mixes are inefficient recyclers of nutrients due to low levels of organic matter which results in reduced microbial activity. Nutrient and water retention is minimal because of low quantities of humus and clay. Essential elements required by turfgrass are easily leached through the sand medium.
Organic-based nutrient products containing humic substances and soluble carbohydrates were tested to increase the stability and efficiency of sand-based greens. The sand medium is enhanced through increased microbial activity, and by growth stimulating compounds supplied by the organic products.
The objectives of the study were i) to compare the effects of five different combinations of organic-based fertilizer products and a control on the establishment of creeping bentgrass (Agrostis palustris Huds. cv. Crenshaw), and ii) to compare the effects of two different application frequency schedules on the development of creeping bentgrass.
The research was conducted on a 100% sand-based golf green. The rooting material contained 10% calcium carbonate (CaCO3) and had a pH of 8.2. Physical analysis of the sand particles showed the rooting medium to be within the standards set by the United States Golf Association (USGA) for golf course green construction. A 900 ft2 area was used to conduct the research. The research was conducted as a randomized complete block design using six treatments in three replications. Each experimental plot had an area of 50 ft2.
The list of treatments and application sequences can be found in the treatment protocol section. Five of the treatments used in the study were liquid fertilizer products, and the sixth treatment was a granular fertilizer material. Four of the liquid treatments, excluding the control, were general use soil conditioners designed to stimulate microbial activity and to provide overall improved soil fertility. The granular treatment was a ground feather meal product containing 56% WIN. All of the liquid treatments were applied to the turf using a CO2 tank and hand-held spray boom. The granular treatment was applied with a hand-held shaker.
Application of the treatments followed a four-week cycle in September and October of 1996. Week one was a 1:1:1 (N,P,K) application with 0.5 lb N, P, and K/1000 ft2 being applied to the turf. Weeks 2-4 used a 2:0:1 (N,P,K) application with 0.5 lb N, and 0.25 lb K/1000 ft2 . The treatments were irrigated after application. A single four-week cycle was completed in 1996. The study was covered by a tarp in November to protect the newly emerged seedlings during the winter months.
Treatments were resumed in the spring of 1997. Changes were made to the research at this time. The plots were split into two 25 ft2 sections, doubling the number of individual plots in the trial. A randomized split block design was used for the 1997 growing season.
The first application in the spring of 1997 was a 1:1:1 starter fertilizer containing 0.5 lb N, P, and K/1000 ft2. This starter fertilizer application occurred on 1 May 1997. It was applied to both sections of the split 50 ft2 plot. Application frequency and product quantity changes were initiated two weeks following the 1:1:1 application. At that time, a switch was made to 2:0:1 treatments. These treatments were applied for the remainder of the season.
Half of the experimental plots received one 0.5 lb N/1000 ft2 application every two weeks (2 applications per month). The other half of the plot received two 0.125 lb N/1000 ft2 applications per week (8 applications per month). The high frequency of applications was designed to imitate fertigation treatments. A total of 1 lb N/1000 ft2 and 0.5 lb K/1000 ft2 was applied each month from 15 May through 18 July. On 18 July, another change was made concerning the rates of N and K that were applied through the treatment applications. The N and K rates were reduced by one-half. This change resulted in 0.5 lb N/1000 ft2 and 0.25 lb K/1000 ft2 being applied to each experimental plot in a one-month period. The new rates were used for the remainder of the season. All treatments were irrigated following application.
Clipping tissue samples were removed and collected seven times throughout the 1997 season following improved maturity of the plots. Individual collection dates were 25 July, 8 and 22 August, 5 and 19 September, 3 October, and 3 November. Clippings were taken 3 to 4 days following the fourth and eighth 0.0625 lb N/1000 ft2 treatment application when all plots had received identical N and K rates. The clippings were dried at 68 ° C for 48-h, dry-ashed, diluted with acid, and analyzed for nutrient content by inductively coupled argon plasma spectrometry (ICAP). Plant tissue nitrogen content was determined using the total Kjeldahl nitrogen procedure (TKN).
Root samples were taken twice during the 1997 growing season. Five one-inch diameter cores were removed from random locations on each plot at a depth of 6 inches. The roots were washed from the sand media using a screening technique. The extracted root material was dried at 78 ° C for 48-h. An oven-dry root mass was taken and the samples were placed into a muffle furnace for 12-h at a temperature of 500 ° C. A second root weight was taken following the ashing procedure. The actual dry root mass of plants grown on each experimental plot was determined by subtracting the dry-ashed root mass from the oven-dry root mass.
Percentage cover data were taken throughout the duration of the research. One set of data was taken in the fall of 1996 and the remainder occurred in 1997. Ratings for percentage cover of grass were between 1 and 100%; where 1% = no grass and 100% = total grass coverage. Visual quality data rating density and color of each plot was taken in the fall of 1997. Quality was rated on a 1 to 9 scale: 1 = poor quality and 9 = highest quality.
Results from clipping analysis are shown in Tables 1 and 2. The tables have been divided into macronutrient (Table 1), and micronutrient (Table 2) concentrations of turfgrass tissue.
Differences in tissue concentration between treatments were shown for phosphorus (P) and sulfur (S) (Table 1). The granular product (Treatment 6) provided significantly higher tissue P and S concentrations compared to the five liquid treatments. Tissue concentrations of the plants grown with the granular treatment were on average 18% and 10% higher for P and S, respectively, than plants supplied with the liquid treatments. Tissue P concentrations were probably higher because the granular product contained 3% P2O5 (12-3-9 formulation). P was not supplied to plots receiving the liquid treatments throughout the 1997 growing season.
Application frequency differences occurred for the macronutrients nitrogen (N), Phosphorus (P), and Sulfur (S) (Table 1). Tissue concentrations were 5%, 7%, and 5% higher for N, P, and S, respectively, in plots receiving 8 applications/month compared to those receiving 2 applications/month.
Treatment differences were shown for the following micronutrients: molybdenum (Mo), nickel (Ni), and zinc (Zn) (Table 2). The molasses product (Treatment 4) provided plants with the highest tissue Mo and Ni concentrations. Turfgrass grown on the granular treated plots had the lowest tissue Mo and Ni concentrations. Highest Zn concentrations for plants grown with the granular treatment were on average 20% higher than plants supplied with the liquid treatments.
The micronutrients Mo and Zn showed differences in application frequency (Table 2). Tissue concentrations were 8% and 7% higher for Mo and Zn, respectively in plots receiving 8 applications/
month compared to the plots that received 2 applications/month.
A treatment effect developed between treatments for percentage turf cover (Table 3). Data taken 4 and 18 June 1997 showed a 28% average lower percentage turf cover value for grass grown on the plots treated with the granular material compared to the grass grown on plots receiving the liquid treatments. Turf coverage was initially slow because nutrients were not immediately available for plant uptake. The granular treatment was a slow release fertilizer containing 56% water insoluble nitrogen for sustained plant response. As nutrients were released for plant uptake, differences in percentage turf cover disappeared. A mean significant difference in percentage turf cover between treatments was shown for the 1997 growing season because of the slow development of grass plants supplied by the granular treatment early in the season. Application frequency did not have an effect on how quickly the grass developed on each plot (Table 3).
Visual quality data taken on 17 Oct. 1997 showed no differences among fertilizer treatments (Table 3). However, plots receiving 8 applications per month had an 8% better quality rating than plots receiving 2 applications/month. The average quality of turfgrass was highest on granular treated plots and lowest on plots receiving the 22% humic acid treatment.
No differences occurred between treatments or application frequency for root development of the grass plants (Table 3). A trend was shown where plants grown on plots treated with molasses had the highest dry root mass, but this was not a significant difference. Plots treated with the 6-0-0, with compost derived organic acids, had the lowest dry root mass.
Consistent differences between the organic-based fertilizer products and the control, which contained no organic material, were not observed in the study. For quicker establishment of 'Crenshaw' creeping bentgrass, liquid fertilizers tended to work better than the granular fertilizer. However, quality was highest at the end of the growing season for plants treated with the granular product. Plants grown on plots treated with lighter, more frequent applications provided higher visual quality ratings. This could be attributed to the higher N, P, S, Mo, and Zn concentrations in tissue of plants grown on plots treated eight times per month compared to those treated only twice. Significant differences in root growth as affected by the treatments or application frequency did not occur in this study. Treatments and application frequency schedules will be resumed in the spring of 1998 to attain second year results.
-Compare the effects of two different application frequency schedules on the growth and development of creeping bentgrass.
Post Germination Treatments (1996)
-Weekly applications at a rate of 0.5lb N/1000 ft2
-Week 1- 1:1:1 N, P, & K
-Weeks 2, 3, & 4- 2:0:1 N, P, & K
-One 4-week cycle was completed in the fall of 1996
Post Germination Treatments (1997)
-2:0:1 treatment applications were used for the remainder of the season
-Half of the plots received one 0.5 lb N/1000 ft2 application every two weeks (2 applications/month), the other half of the experimental plots received two 0.125 lb N/1000 ft2 applications per week (8 applications/month)-These rates were used May 15 through July 18. On July 18 the application rates were reduced by one-half.
-All experimental plots received 1.0 lb N/1000 ft2 and 0.5 lb K/1000 ft2 per month from May 15 to July 18.
-Experimental plots received 0.5 lb N/1000 ft2 and 0.25 lb K/1000 ft2 per month from July 18 to end of the 1997 growing season.
*1:1:1 treatment applications were made on 15 September 1996, and 15 May 1997. These treatments contained phosphorus and were applied as a starter fertilizer.
2. 8-16-4 w/compost-derived organic acids as P source; KNO3 as K source; and remaining N from NH4NO3
3. 15% humic acid ; H3PO4 as primary P source; KNO3 as primary K source; and remaining N from NH4NO3
4. 5-3-2 w/molasses ; H3PO4 as primary P source; KNO3 as primary K source; remaining N from NH4NO3
5. (Control) H3PO4 as P source; KNO3 as K source; remaining N from NH4NO3.
6. 12-16-8 granular & 12-3-9 granular at 0.5lb N/1000 ft2
2. 6-0-0 w/compost derived organic acids ; KNO3 as K source; remaining N from NH4NO3
3. 15% humic acid ; KNO3 as K source; remaining N from NH4NO3
4. 5-3-2 w/molasses ; KNO3 as primary K source; remaining N from NH4NO3
5. (Control) KNO3 as K source; remaining N from NH4NO3
6. 12-3-9 granular ground feather meal product
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