iron in the fire: how does bermudagrass respond?
TRANSCRIPT
Iron in the Fire:How Does Bermudagrass
Respond?
Travis Shaddox, Ph.D.
Background
Most turf managers use an Fe component in granular fertilizer
Soil test may or may not recommend applications of Fe in Florida soils
No consideration is given to the form of Fe
Iron is an economic concern, not environmental.
Objective
To determine the influence of various Fe sources on turf response
Materials and Methods
Treatments– Untreated
– Iron Sulfate
– Iron Sucrate
– Iron Humate
– Iron Chelate (5% EDTA)
– Iron Oxide
– Iron Sulfate - Foliar
Rate– 20 lb Fe / A
Locations– Citra - Princess
– Jay – Tifgrand
6 weeks
Site Information
Citra
Princess Bermuda
Trts applied May 7
No prior fertilization
Soil pH 7.2
Turf was not acceptable at initiation
Jay
Tifgrand Bermuda
Trts applied July 7
Fertilized 4 weeks prior
Soil pH 7.3
Turf was acceptable at initiation
Variables Analyzed
Rapid Laboratory Extraction
Soil Incubation
Turf Quality– 1 to 9
Yield– grams
NDVI– Normalized difference vegetation index
– Measures natural green color
Rapid Extraction Setup
Rapid Lab Extraction
Extr 0 Extr 1 Extr 2 Extr 3 Extr 4
Fe
Ext
ract
ed (
%)
0
50
100
150
200
250
300
350
Sulfate Sucrate Humate Oxide Chelate
Cumulative Fe Extracted (%)
313 a
103 b
35 c
4 d 0.5 d0
50
100
150
200
250
300
350
Chelate Sulfate Humate Sucrate Oxide
Aerial Photo – Citra week 3
Turf Quality - Jay
Jay - Tifgrand
Days after Fertilization
0 7 14 21 28 35
Tur
f Q
ualit
y
4
5
6
7
8
9
10Control Sulfate Sucrate Humate Oxide Chelate Sulfate-F
Turf Quality - Citra
3
4
5
6
7
8
9
0 5 10 15 20 25 30
Turf
Qu
alit
y
Days After Initiation
2014
Control
EDTA
Foliar
Humate
Oxide
Sucrate
Sulfate
Turf Quality - Citra
3
4
5
6
7
8
9
0 5 10 15 20 25 30
Turf
Qu
alit
y
Days After Initiation
2015
Control
EDTA
Foliar
Humate
Oxide
Sucrate
Sulfate
Turf Quality
a
b bc bc bc bc c
4
5
6
7
8
9
Sulfate-F Chelate Sulfate Sucrate Oxide Humate Control
Jay - 16 DAA
Turf Quality
a
b b b bcbc
c
4
5
6
7
8
Sulfate-F Sucrate Humate Control Chelate Oxide Sulfate
Citra - 4 DAA
NDVI
Jay - Tifgrand
Days after Fertilization
0 7 14 21 28 35
ND
VI
0.52
0.54
0.56
0.58
0.60
0.62
0.64
0.66
Control Sulfate Sucrate Humate Oxide Chelate Sulfate-F
Citra - Princess
Days after Fertilization
0 7 14 21 28 35
ND
VI
0.52
0.54
0.56
0.58
0.60
0.62
0.64
0.66
Control Sulfate Sucrate Humate Oxide Chelate Sulfate-F
NDVI
a
ab abb b
b b
0.56
0.57
0.58
0.59
0.6
0.61
0.62
Sulfate-F Chelate Humate Oxide Control Sulfate Sucrate
Jay - 21 DAA
NDVI
aa a
ab ab
ab
b0.56
0.57
0.58
0.59
0.6
0.61
0.62
Sulfate-F Control Humate Chelate Sulfate Sucrate Oxide
Citra - avg
Yield
Citra - Princess
Days after Fertilization
7 14 21 28 35
Yie
ld (
g)
2
4
6
8
10
12Control Sulfate Sucrate Humate Oxide Chelate Sulfate-F
Jay - Tifgrand
Days after Fertilization
7 14 21 28 35
Yie
ld (
g)
2
4
6
8
10
12
14
16
18Control Sulfate Sucrate Humate Oxide Chelate Sulfate-F
Average Yield (g)
a a a a a a
a
0
10
20
30
40
50
60
Control Sucrate Humate Chelate Oxide Sulfate-F Sulfate
Jay
Citra
Average Yield (g)
a a a a a a
a
aa a a
a
a a
0
10
20
30
40
50
60
Control Sucrate Humate Chelate Oxide Sulfate-F Sulfate
Jay
Citra
WHY IS TURFGRASS RESPONDING TO FOLIAR IRON?
Soil Incubation
Objective
To determine the solubility of Fe applied as sulfate or glucoheptonate in 2 Florida Soils
Soil Incubation
Methodology
2 soils– Citra
– Jay
2 Iron Products– Sulfate
– Glucoheptonate
Extractions– 1h, 4h, 1d, 1wk, 2wk, 3wk
Soluble Fe – Citra Soil
0
25
50
75
100
1 h 4 h 1 d 1 wk 2 wk 3 wk
% o
f A
pp
lied
Length of Incubation
Sulfate
Glucoheptanate
Soluble Fe – Jay Soil
0
25
50
75
100
1 h 4 h 1 d 1 wk 2 wk 3 wk
% o
f A
pp
lied
Length of Incubation
Sulfate
Glucoheptanate
Summary
Chelate and sulfate produced the highest amounts of extractable Fe
Foliar sulfate increased turf quality on Princess and Tifgrand
Tifgrand - foliar sulfate and chelate were the only source that increase turf color
No source influenced yield
Importance
Granular Fe increases the cost of granular fertilizer and does not increase turfgrass quality– We have observed a response to granular Fe (EDTA
& Humate) in 1 of 9 studies!
Foliar applications should be considered– 6 studies on 3 different turfgrasses in 2 locations and
2 years - we have observed a response to foliar Fe in every study
Contact Info
Travis Shaddox
University of Florida
Environmental Horticulture
office 352-273-4591
cell 352-262-3426
@TravisShaddox