1998 Iowa Turfgrass Research Report
1997 Kentucky Bluegrass Fertility Study
Barbara R. Bingaman, Nick E. Christians, & Michael B. Faust
The purpose of this study was to evaluate the response of Kentucky bluegrass to various natural organic and commercial fertilizers. The experimental plot was an established area of 'Park' Kentucky bluegrass at the Iowa State University Horticulture Station north of Ames, Iowa. The soil in this area was a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with 3.3% organic matter, a pH of 6.5, 3 ppm P, and 80 ppm K. Irrigation was used to supplement rainfall and maintain the turf in good growing condition.
The experiment was arranged in a randomized complete block design. Individual plots were 5 x 5 ft and three replications were conducted. Three-foot barrier rows were placed between replications to facilitate taking clippings.
All fertilizers were applied in the spring and late summer at a yearly rate of 4 lb N/1000 ft2 (Table 1). There were 11 treatments including eight different fertilizers and an untreated control. Two soybean-based natural products from Renaissance Fertilizer Co. (6-0-6 and 8-2-6) were applied at 2 lbs N/1000 ft2 followed by 2 lbs N/1000 ft2, and at 3 lbs N/1000 ft2 followed by 1 lb N/1000 ft2. Corn gluten meal from Grain Processing Inc., Safe & Simple (a different particle configuration of corn gluten meal) from Blue Seal Feeds, Milorganite (processed sewage sludge), Poly PlusÔ sulfur coated urea (39-0-0) from LESCO Inc., and Proturf (32-3-10) from The Scotts Company also were included. These products were applied in split applications at 2 lbs N/1000 ft2. In addition, a liquid product, Green Lawn, was applied monthly May through September (5 applications) at 0.8 lb N/1000 ft2.
Prior to treatment the plot was mowed to a uniform height of 2 inches A survey of the area was made before application and turf quality was uniform. Granular fertilizers were applied using 'shaker dispensers'. Green Lawn was applied at 30 psi using a CO2 backpack sprayer equipped with TeeJet #8006 flat fan nozzles. It was mixed in 283 ml of water which translates to an application rate of 3 gal/1000 ft2.
Initial applications were made on May 15. Late summer sequential applications were made on July 31. Green Lawn was applied on May 15, June 11, July 10, July 31, and September 5.
It was a very cool and dry spring. In April, there was only one substantial rainfall with total rainfall for the month under 1.5 inches. In May and June, the rainfall events were sporadic. This trend continued in July and August. Because of this, irrigation was heavily relied on to keep the bluegrass in good growing condition.
Visual turf quality and fresh clipping weight data were taken weekly from May 21 through October 2. Visual quality was assessed using a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst turf quality (Tables 2 and 3). Mowing height for taking clippings was 2 inches (Tables 3 and 4).
Data were analyzed with the Statistical Analysis System (SAS) version 6.10 and the Analysis of Variance Procedure (ANOVA). Fisher's Least Significant Difference test (LSD) was used to compare means.
There was no phytotoxicity on the treated bluegrass. The visual quality of all fertilized bluegrass was significantly better than the untreated control from May 30 through October 2 (Table 2 and 3). The quality of all fertilized turf did not fall below the acceptable quality level (a rating of 6) for the entire season. Sulfur coated urea, Proturf, and Renaissance (6-0-6) at 3 lb N followed by 1 lb N/1000 ft2 (treatment 4) produced the best mean quality. The effects of these treatments were not different from those of corn gluten meal, Renaissance (6-0-6) at 2 lb N followed by 2 lb N/1000 ft2 (treatment 3), Renaissance (8-2-6) at 3 lb N followed by 1 lb N/1000 ft2 (treatment 6), and Safe & Simple.
Two commercial fertilizers, Proturf and sulfur coated urea, caused rapid bluegrass quality improvements following initial and sequential applications. The response to the natural product fertilizers, corn gluten meal, Renaissance (6-0-6 and 8-2-6), and Safe & Simple, generally was slower but was maintained longer. After the initial treatments, the best quality through May 30 was found in bluegrass treated with Proturf and sulfur coated urea. By June 4, the visual quality of bluegrass treated with the soybean products (Renaissance 6-0-6 and 8-2-6) applied at 3 lb N followed by 1 lb N/1000 ft2 was similar to bluegrass treated with Poly-Plus (Table 2 and 3).
Untreated bluegrass produced the least fresh clippings from June 4 through the end of the study. For the period from June 4 through July 30, the most clippings were from bluegrass treated with Renaissance (8-2-6) at 3 lb N followed by 1 lb N/1000 ft2 (treatment 6). During this period, similar weights were produced by Poly-Plus on June 4, June 10, July 9, July 22, and July 30; by Proturf on June 4; and by Renaissance (6-0-6) at 3 lb N followed by 1 lb N/1000 ft2 (treatment 4) on June 18, June 25, July 9, July 15, July 22, and July 30. On July 2, corn gluten meal had comparable clipping weights. On July 22 and July 30, the clipping weights in bluegrass treated with Green Lawn and Safe & Simple were similarly high.
Mean and total clipping weights from untreated bluegrass were significantly less than clippings from treated bluegrass (Table 4). The largest mean and total clipping weights were from bluegrass treated with Renaissance (8-2-6) at 3 lb N followed by 1 lb N1000 ft2 (treatment 6) but they were similar to those weights from all other fertilizers except Milorganite.
Table 1. Application rates for fertilizer materials used in the 1997 Kentucky Bluegrass Fertility Study.
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application1 |
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N/1000 ft2 |
lbs N /1000 ft2 |
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lbs N /1000 ft2 |
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1 |
Untreated control |
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2 |
Corn gluten meal (10% N) |
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3 |
Renaissance (6-0-6)3 |
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4 |
Renaissance (6-0-6)3 |
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5 |
Renaissance (8-2-6)3 |
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6 |
Renaissance (8-2-6)3 |
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7 |
Milorganite (6-2-0) |
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8 |
Proturf (32-3-10)4 |
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9 |
Safe & Simple (10% N) |
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10 |
Sulfur coated urea (39-0-0)5 |
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11 |
Green Lawn (26-4-2)6 |
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1Initial applications were made on May 15, 1997.
2Sequential applications were made on July 30, 1997. Green Lawn fertilizer was applied 5 times (May 15, June 11, July 10, July 30, and September 5.
These products are being screened for 3 Renaissance Fertilizer Company, 4The Scotts Company, 5LESCO,and 6Green Lawn (applied monthly for a total yearly rate of 4.0 lb N/1000 ft2).
Table 2. Visual quality of Kentucky bluegrass for May 21 through July 22 for the 1997 Kentucky Bluegrass Fertility Study.
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1 |
Untreated control |
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2 |
Corn gluten meal (10% N)1 |
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3 |
Renaissance (6-0-6)1&3 |
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4 |
Renaissance (6-0-6)2&3 |
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5 |
Renaissance (8-2-6)1&3 |
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6 |
Renaissance (8-2-6)2&3 |
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7 |
Milorganite (6-2-0)1 |
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8 |
Proturf (32-3-10)1&4 |
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9 |
Safe & Simple (10% N)1 |
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10 |
Sulfur coated urea (39-0-0)1&5 |
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11 |
Green Lawn (26-4-2)6 |
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LSD0.05 |
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1These materials were applied in split spring and late summer applications at 2 lbs N/1000 ft2 .
2These products were applied in spring and late summer applications at 3 lbs N/1000 ft2 and 1 lb N/1000 ft2, respectively.
3These products were screened for Renaissance Fertilizer Company, 4The Scotts Company, 5LESCO, and 6Green Lawn (applied monthly for a total yearly rate of 4.0 lb N/1000 ft2).
Visual quality was assessed using a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst quality.
Initial applications were made on May 15,
1997 and sequentials on July 30, 1997. Green Lawn
applications were made on May 15, June 11, July 10, July
31, and September 5.
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |