1998 Iowa Turfgrass Research Report
Responses of Creeping Bentgrass to Organic and Inorganic Soil Amendments Under Stressed Conditions
Young K. Joo, J. P. Lee, David D. Minner, and Nick E. Christians
The objectives of this research were to investigate the effects of inorganic soil amendments on the growth of creeping bentgrass established on a sand-based soil media under stressed conditions. The organic amendments included hypnum, Dakota, and Irish peat at 10% v/v (volume/volume) of the sand mix. The inorganic amendments included Axis (a diatomaceous earth), Profile (a porous ceramic clay), Flex-A-Clay (a polymer coated sand), and Bio-ceramic (a ceramic material from Korea). Following establishment, the grass was subjected to water, nutrient, and high temperature stress. The study was initiated in June, 1996 and was terminated in January 1997.
The amendments were uniformly incorporated into the upper 14 inches of the sand column. The treatments included a pure sand control, and the amendments were mixed at 10% v/v of mixture. Bio-ceramic was also included at 5% of the mixture. The sand and other materials used in the columns were sieved to meet particle size specifications of a USGA green. Soil profiles in the columns followed USGA recommendations for putting green construction. Each profile had an intermediate 4-inch choker layer and a 6-inch pea gravel sub-layer. The 24-inch profiles were established in a clear plastic sleeve with a 1.5 in2 surface area. The sleeves were placed in a PVC pipe with 2 inch inside diameter. The sleeve was sealed on one end and punctured to provide drainage. 'Crenshaw' creeping bentgrass was seeded on the column surface at the equivalent of 1 lb seed/1000 ft2 . The grass was grown under normal conditions for four weeks. High pressure sodium lamps were used as the light source and greenhouse temperature was maintained at 65 to 72° F. The tubes were tilted on a 30° angel from vertical at the end of the 4-week establishment period to force the roots to grow down the lower side of sleeve. This allowed for a biweekly, nondestructive measurement of root growth. The study was designed as a randomized complete block with four replications.
The water and nutrient stress treatments were started at the 4th week and lasted three months. The tubes were irrigated at least two times/week with a total of 2 inches of water for normal grass growth. Water stress treatments received one-quarter of the water applied to the other normal units. The normal fertilizer treatment received 0.5 lbs. N/1000 ft2 (1:1:1 N, P2O5,, K2O) every two weeks. The nutrient stressed units received one-fourth of the normal fertilization rate. High temperature stress treatments were started after three and one-half months of the normal growing conditions in the greenhouse. The high temperatures were established in a growth chamber set at 95° F (day) and 85° F (night). The high temperature treatments were maintained for 16 weeks.
Visual turf quality, dry weight of clippings, and root length were measured every two weeks. Root weight data were collected at harvest.
Both organic and inorganic amendments produced better quality ratings than the control under normal, moisture stressed, and low nutrient conditions. The organic treatments generally provided higher quality than the inorganics (Table 1). The inorganic amendments did not produce greater clipping yields than the control under normal and low nutrient conditions. They did, however, improve growth under moisture stressed conditions. Organic amendments increased clipping yields over the control and over the inorganic amendments under all three conditions (Table 2).
Root lengths generally increased for both inorganic and organic amended treatments for both normal and moisture stressed conditions, with organic treatments generally exceeding inorganics. Neither group of soil amendments improved root length in low nutrient conditions. Total root weights were not improved by inorganic or organic amendments in normal and low nutrient conditions. Both amendments improved total root mass under moisture stressed conditions (Table 3).
There were no significant effects of amendments on clipping production during the first three months of high temperature treatment (Table 4). By the end of the 4th month, the grass grown on columns with Dakota peat had much higher clipping weights than any of the other treatments. Turf quality ratings were generally improved by inorganic and organic amendments, with Flex-A-Clay (small) and Dakota peat providing the highest ratings. Total plant weight at termination (HTTW) was enhanced by inorganic and organic amendments.
Table 1. Visual quality ratings for columns receiving normal moisture and fertility levels.
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Amendment |
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Pure Sand (Control) |
4.25 |
5.25 |
4.75 |
6.00 |
6.75 |
7.25 |
5.71 |
4.25 |
4.00 |
3.50 |
3.50 |
4.00 |
3.75 |
3.83 |
3.75 |
4.50 |
4.75 |
5.25 |
3.75 |
4.00 |
4.33 |
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Inorganic |
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Bio-ceramic 5% |
4.50 |
5.75 |
6.00 |
7.75 |
8.25 |
8.25 |
6.75 |
4.00 |
4.50 |
6.00 |
6.00 |
6.25 |
5.75 |
5.42 |
5.50 |
7.50 |
6.75 |
6.75 |
6.00 |
5.00 |
6.25 |
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Bio-ceramic 10% |
5.00 |
6.00 |
6.75 |
8.25 |
8.25 |
8.50 |
7.13 |
4.75 |
3.75 |
5.25 |
5.25 |
5.00 |
5.00 |
4.92 |
5.50 |
7.00 |
7.00 |
6.75 |
5.75 |
4.75 |
6.13 |
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Profile |
5.25 |
6.25 |
5.75 |
7.00 |
7.50 |
8.75 |
6.75 |
6.50 |
5.25 |
3.50 |
3.50 |
3.50 |
4.25 |
4.42 |
5.00 |
6.25 |
6.25 |
5.75 |
5.00 |
4.50 |
5.46 |
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Axis |
5.50 |
6.75 |
6.75 |
8.00 |
8.00 |
7.75 |
7.13 |
4.25 |
4.00 |
4.00 |
4.75 |
4.25 |
4.75 |
4.33 |
4.00 |
6.50 |
5.75 |
5.75 |
5.50 |
4.50 |
5.33 |
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Flex-A-clay (Large) |
4.75 |
6.00 |
6.75 |
8.00 |
7.25 |
7.25 |
6.67 |
4.00 |
4.25 |
5.25 |
5.75 |
5.00 |
5.50 |
4.96 |
5.25 |
6.50 |
7.00 |
6.50 |
5.00 |
4.50 |
5.79 |
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Flex-A-clay (Small) |
4.50 |
7.25 |
6.50 |
8.25 |
8.50 |
9.00 |
7.33 |
4.25 |
4.75 |
6.00 |
6.75 |
5.75 |
5.75 |
5.54 |
5.25 |
6.25 |
6.25 |
6.25 |
5.25 |
4.00 |
5.54 |
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Organic |
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Hypnum peat |
4.75 |
6.25 |
7.25 |
7.25 |
6.75 |
8.50 |
6.79 |
4.50 |
5.50 |
7.25 |
7.00 |
6.50 |
7.00 |
6.30 |
4.75 |
5.75 |
6.50 |
6.00 |
4.75 |
4.50 |
5.38 |
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Dakota peat |
7.00 |
8.75 |
8.50 |
8.00 |
8.25 |
8.50 |
8.17 |
7.00 |
9.00 |
7.00 |
6.75 |
7.00 |
6.50 |
7.21 |
6.75 |
9.00 |
8.25 |
7.50 |
6.50 |
6.00 |
7.33 |
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Irish peat |
6.00 |
6.25 |
8.25 |
8.50 |
7.50 |
9.00 |
7.58 |
6.25 |
7.50 |
7.50 |
6.50 |
6.25 |
5.75 |
6.63 |
6.25 |
8.00 |
7.25 |
6.50 |
6.00 |
5.75 |
6.63 |
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LSD.05 |
N.S |
1.54 |
1.69 |
N.S |
N.S |
1.08 |
0.75 |
1.39 |
1.70 |
1.77 |
1.31 |
1.56 |
1.61 |
0.90 |
1.55 |
1.50 |
N.S |
1.16 |
1.32 |
N.S |
0.76 |
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Pure sand vs. Inorganic (p-value) |
0.28 |
0.07 |
0.01 |
0.00 |
0.04 |
0.02 |
0.00 |
0.48 |
0.52 |
0.03 |
0.00 |
0.11 |
0.02 |
0.00 |
0.03 |
0.00 |
0.02 |
0.02 |
0.00 |
0.38 |
0.00 |
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Pure sand vs. Organic (p-value) |
0.02 |
0.01 |
0.00 |
0.00 |
0.21 |
0.00 |
0.00 |
0.01 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.04 |
0.00 |
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Inorganic vs. Organic (p-value) |
0.02 |
0.01 |
0.00 |
0.90 |
0.22 |
0.13 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.01 |
0.00 |
0.04 |
0.02 |
0.07 |
0.20 |
0.31 |
0.03 |
0.00 |
Q1 to Q6 = biweekly quality ratings; 9 = best and 1 = worst quality. MQ = mean quality.
Table 2. Dry clipping weights for columns receiving normal, moisture stress, and low nutrient treatments.
Amendment
C1
C2
C3
C4
C5
TC
C1
C2
C3
C4
C5
TC
C1
C2
C3
C4
C5
TC
Pure Sand (Control)
Inorganic
Bio-ceramic 5%
0.02
0.07
0.15
0.18
0.24
0.66
0.04
0.02
0.15
0.17
0.07
0.44
0.03
0.09
0.15
0.16
0.03
0.47
Bio-ceramic 10%
0.03
0.07
0.18
0.20
0.25
0.73
0.03
0.04
0.14
0.11
0.08
0.40
0.05
0.12
0.15
0.09
0.03
0.44
Profile
0.04
0.09
0.17
0.17
0.24
0.72
0.06
0.01
0.03
0.07
0.07
0.25
0.04
0.12
0.16
0.10
0.02
0.44
Axis
0.03
0.11
0.17
0.22
0.20
0.73
0.03
0.03
0.10
0.11
0.10
0.38
0.03
0.08
0.11
0.11
0.03
0.37
Flex-A-clay (Large)
0.03
0.07
0.32
0.17
0.22
0.81
0.04
0.05
0.14
0.16
0.10
0.49
0.05
0.14
0.15
0.16
0.03
0.53
Flex-A-clay (Small)
0.02
0.06
0.16
0.12
0.19
0.54
0.02
0.04
0.16
0.17
0.13
0.52
0.04
0.12
0.15
0.17
0.02
0.51
Organic
Hypnum peat
0.04
0.09
0.23
0.23
0.20
0.80
0.05
0.14
0.22
0.16
0.09
0.66
0.04
0.13
0.15
0.13
0.03
0.47
Dakota peat
0.12
0.22
0.29
0.26
0.28
1.17
0.11
0.22
0.13
0.09
0.08
0.63
0.13
0.25
0.17
0.14
0.05
0.74
Irish peat
0.04
0.14
0.25
0.24
0.23
0.90
0.07
0.14
0.17
0.19
0.07
0.64
0.08
0.14
0.14
0.21
0.05
0.62
LSD.05
0.02
0.06
N.S
N.S
N.S
0.28
0.03
0.05
0.06
0.07
N.S
0.10
0.04
0.07
N.S
N.S
N.S
0.18
Pure sand vs. Inorganic
(p-value)
0.92
0.22
0.17
0.77
0.99
0.21
0.34
0.50
0.00
0.01
0.14
0.00
0.19
0.20
0.53
0.46
0.88
0.16
Pure sand vs. Organic
(p-value)
0.00
0.00
0.03
0.06
0.81
0.00
0.00
0.00
0.00
0.00
0.36
0.00
0.00
0.00
0.31
0.21
0.14
0.00
Inorganic vs. Organic
(p-value)
0.00
0.00
0.13
0.01
0.71
0.00
0.00
0.00
0.00
0.41
0.44
0.00
0.00
0.00
0.47
0.36
0.03
0.00
C1 to C5 = biweekly clipping weight in grams. TC = total clipping weight based on 9.6cm2
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ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |