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J rs WEST FLORIDA RESEARCH AND EDUCATION CENTER
; Jay, Florida 32565-9524
Jay, WFREC Research Report WF95-4 February, 1995
Response of Tifton 78 Bermudagrass to Varied Rates of Potassium
L. S. Dunavin1
Tifton 78 bermudagrass has been observed to often fail to persist for more than
a very few years. There have been some indications that fertilization with high
rates of potassium (K) might help to lengthen the time of stand persistence.
A trial to determine response to varied amounts of potassium was established on
a 3-year old stand of Tifton 78 bermudagrass in May of 1992. The soil was a
Tifton sandy loam (Plinthic Paleudult). Plots measured 5' X 10', were separated
by 10' alleys, and were replicated four times. Five rates of K (60, 120, 180,
240, and 300 lbs. per acre) were applied as 8-24-24 in the first case and 8-24-
24 plus muriate of potash in the required additional amounts in the other cases.
Phosphorus (P) was applied in all cases at the rate of 32 pounds per acre in 8-
24-24, and nitrogen (N) was applied at 24 pounds per acre in 8-24-24 and an
additional 120 pounds as ammoniate nitrate which was divided into three equal
applications during the growing season. The complete fertilizer plus extra K
was applied on 22 May 92 and additional N on 22 May 92, 2 July 92, and 10 Aug.
92. In 1993, the complete fertilizer plus extra K was applied on 27 April and
additional N was applied on 25 May, 9 July, and 18 Aug. 93. One ton per acre of
dolomitic limestone was applied in March, 1993. Harvests were obtained on 24
June, 28 July, and 25 Aug. 92 and on 21 May, 16 June, 19 July, 1i Aug., and 14
Sept. 93.
Stands were rated on 26 May 92 and on 17 May 94. These data are presented in'
Table 1 and show no significant difference among the stands at the various K
levels on either date. Stands only averaged 78% at the earlier date and averaged
37% approximately two years later. The average stand loss was 41%, and there was
no significant difference among K levels. Yield data are shown in Tables 2 and 3
and indicate that the additional K did not significantly increase yield in either
year.
There was no apparent value to the increased use of K with regard to persistence
of Tifton 78 bermudagrass.
I;:i-~i Science
Library
MAR 2 7 1o
University of Florida
1Associate Professor of Agronomy.
Table 1. Tifton 78 Bermudagrass Potassium Trial, AREC, Jay, 1992-1994.
Average Estimated Standt
___________% _ _
Entry 26 May 92 17 May 94 Loss
2-1-1* 83 44 39
2-1-2 78 40 38
2-1-3 78 33 45
2-1-4 79 25 54
2-1-5 74 43 31
Avg. 78 37 41
.N.S.' **.*S*" '"' N. S. :' 'N S.
No significant difference in estimated stands among entries on 26 May
92 or on 17 May 94, and no significant difference in stand loss.
NOTE: This area was established to Tifton 78 bermudagrass in April, 1989.
tAverage of four replications.
*2-1-1 = 144-72-72 (N-P205-K20).
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Table 2. Tifton 78 Bermudagrass Potassium Trial, AREC, Jay. 1992.
.----- Dry Matter
- Pounds per acret
Entry 24 June 28 July 25 Aug. Total
2-1-1* 1880 1730 1630 5240
2-1-2 2200 1700 1430 5330
2-1-3 2350 1550 1480 5380
2-1-4 1700 1540 1570 4810
2-1-5 2110 1760 1840 5710
LSD (t .05) N.S. 'N.S. N.S. N.S.
tPounds per acre X 1.12 = kilograms per hectare.
*2-1-1 = 144-72-72 (N-P205-K20).
SOIL: Tifton sandy loam (Plinthic Paleudult).
FERTILIZER': 8-24-24 and all additional K applied on 22 May 92.
Additional N applied on 22 May, 2 July, and 10 Au-
gust, 92.
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UNIVERSITY OF FLORIDA
3 1262 07468 195 7
Table 3. Tifton 78 Bermudagrass Potassium Trial, AREC, Jay. 1993.
Dry Matter
Entry Pounds per acret
21 May 16 June 19 July 17 Aug. 14 Sept. Total
2-1-1* 670 720 900 310 570 3170
2-1-2 770 640 1020 390 740 3560
2-1-3 660 630 890 370 610 3160
2-1-4 610 670 1020 400 760 3460
2-1-5 910 720 1180 510 780 4100
LSD (t .05) N.S. NS.' N : .- N.S. N.S. N.S N.S.
tPounds per acre X 1.12 = kilograms per hectare.
*2-1-1 = 144-72-72 (N-P205-K20).
SOIL: Tifton sandy loami (Plinthic Paleudult).
FERTILIZER: 8-24-24 and all additional K applied on 27 April
93. Additional N applied on 25 May, 9 July, and 18
Aug. 93.
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