TX-53F Haby 07 Annual Rpt.pdf

TX-53
Table 10. Tifton 85 bermudagrass Zn conc. response to N and K rates and K, Cl, and S sources, 2007.
N rate Plant Zn concentration †
lb/ac/harv. Harvest 1 Harvest 2 Harvest 3 Harvest 4 Harvest 5 Season avg.
--------------------------------------------------ppm------------------------------------------------
60 21.3 b 20.4 15.4 18.9 8.9 17.0 b
120 24.9 a 21.2 17.8 21.2 12.1 19.4 a
K rate
lb K 2 O/ac
0 24.7 17.9 17.3 19.8 13.8 18.7
134 21.7 22.1 16.5 20.4 10.3 18.2
268 23.0 20.1 15.3 19.9 9.7 17.6
402 24.1 21.2 17.8 20.1 10.3 18.7
K Source
KCl 21.1 b 17.8 b 14.6 b 19.6 b 10.1 b 16.6 b
KMag+KCl 20.4 b 16.5 b 14.1 b 16.7 b 8.6 c 15.3 b
ACT 62D+KCl 27.3 a 29.0 a 20.9 a 24.1 a 11.6 a 22.6 a
R 2 0.78 0.72 0.72 0.70 0.92 0.88
c.v. 23.9 25.5 22.3 26.7 17.5 13.6
† Values in a column/group followed by a dissimilar letter are significantly different statistically (α = 0.05).
Table 11. Tifton 85 bermudagrass Zn uptake response to N and K rates and K, Cl, and S sources, 2007.
N rate Plant Zn uptake †
lb/ac/harv. Harvest 1 Harvest 2 Harvest 3 Harvest 4 Harvest 5 Season total
-------------------------------------------------lbs/ac ‡ -----------------------------------------------
60 0.029 b 0.067 0.048 0.058 0.012 0.214 b
120 0.035 a 0.073 0.056 0.070 0.014 0.249 a
K rate
lb K 2 O/ac
0 0.016 b 0.029 b 0.024 c 0.031 b 0.008 b 0.108 c
134 0.029 a 0.070 a 0.048 b 0.062 a 0.010 b 0.220 b
268 0.036 a 0.074 a 0.051 b 0.067 a 0.014 a 0.242 b
402 0.037 a 0.080 a 0.068 a 0.074 a 0.016 a 0.274 a
K Source
KCl 0.030 b 0.058 b 0.045 b 0.066 b 0.013 b 0.211 b
KMag+KCl 0.029 b 0.059 b 0.043 b 0.055 b 0.012 b 0.198 b
ACT 62D+KCl 0.043 a 0.107 a 0.079 a 0.083 a 0.016 a 0.326 a
R 2 0.67 0.80 0.80 0.69 0.82 0.89
c.v. 35.9 27.1 30.0 32.0 31.6 16.7
† Values in a column/group followed by a dissimilar letter are significantly different statistically (α = 0.05).
‡ To convert pounds to grams, multiply pounds by 453.6.
The S concentration of Tifton 85 bermudagrass was increased by the higher N rate in the third and fourth
harvests and in the season average. The main effect higher K rates increased S concentration and S
uptake by the bermudagrass. As the K source changed from KCl to KMag+KCl and to ACT 62D+KCl
the S concentration and S uptake by Tifton 85 bermudagrass were significantly increased. It is uncertain
if there was more residual S in these plots that had received all the previous S treatment as elemental
S+KCl than in plots now treated with KMag+KCl that had received previous S treatments as K 2 SO 4 .
With this in mind, is the highest S in grass grown on the current ACT 62D+KCl plots actually from the
ACT 62D+KCl, or is the increased plant S from residual soil S? There is significantly more S in the 0- to
6-inch depth of soil currently treated with ACT 62D+KCl. Total S uptake ranged from 23 to 67 lb/ac.
7