turfgrass and k: reviewing the relationship
TRANSCRIPT
Turfgrass & K: Reviewing the RelationshipThursday, Dec. 10, 2015
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PresentersDoug Soldat, Ph.D., Department of Soil Science
Mark Davis, Senior Agronomist
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Agenda• Webinar user instructions• Presentation• Participant questions
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• 2nd Most abundant mineral nutrient• Does not have any structural role• Important in turgor and water relations, cofactor for enzymes, “stress” tolerance
Potassium in the PlantSponsored by:
• Increased rooting?• “Winterizer”?• Increased drought tolerance?• Increased wear tolerance?• Disease susceptibility?
Benefits of K Fertilization
Drew, M.C. 1975. New Phytologist. 75(3):479
Drew, M.C. 1975. New Phytologist. 75(3):479
Drew, M.C. 1975. New Phytologist. 75(3):479
From: Drew, 1975
Effect of soil P+ K on Root Distribution
• Increased cold tolerance– Bermudagrass (Adams & Twersky, 1960; Alexander & Gilbert, 1963;
Gilbert & Davis, 1971; Juska & Murray, 1974)– Centepedegrass (Palmertree et al., 1974)
• No effect– Tall fescue (Cook & Duff, 1976)– Perennial ryegrass (Turner, 1980)
Cold Tolerance?(includes freezing tolerance and winter injury)
Adam Moeller @AdamMoeller Mar 16Rutgers Poa plots with < 50 ppm soil K much more damaged from freeze injury compared to those with higher soil K
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• Improved Wear Tolerance:– Shearman and Beard (1973)
• No Effect on Wear Tolerance or Recovery:– Hawes and Kecker (1977)– Carrow et al. (1987)– Carroll and Petrovic (1991)– Trenholm et al. (2001)– Hoffman et al. (2010 a and b)
Wear Tolerance?Sponsored by:
Drought Tolerance?
• Delayed Wilting:– Waddington et al., 1978– Escritt and Legg, 1970 –
took 20 years to show up– Huang, 2001
• Faster Recovery:– Schmidt and Breuninger,
1981– Grady and Dickens, 1997
• No effect:– DiPaola and Engel, 1976
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Diseases Tolerance?
K & Recovery from Snow Mold
Per
cent
sno
w m
old
inci
denc
e
From Woods et al. 2006
K2O applied – lbs/M0 3 6 10 13 16 19 0 3 6 10 13 16 19
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Per
cent
sno
w m
old
inci
denc
e
0 3 6 10 13 16 19 0 3 6 10 13 16 19
K & Recovery from Snow Mold
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From Woods et al. 2006
K2O applied – lbs/M
Potassium fertilization affects psychrophilic pathogen susceptibility of annual bluegrass
David R. Moody and Frank S. RossiCornell UniversityNovember 1, 2010
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“Mid-winter”Constant temperature (- 4ºC)
Buried in snow to prevent desiccation
Inoculation0 d 90 d 180 d 208 d 236 d 316 d
Establishment K Treatments ‘Hardening’ ‘Mid-winter’ ‘Early-spring’
Greenhouse Low Temperature Reefer
Inoculation
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Tiss
ue K
Con
tent
(g k
g-1
)
05
10152025303540
Fertilization Period
K Treatment(180d)
'Hardening'(208d)
'Mid-winter'(236d)
'Early Spring'(316d)
Stage of Experiment Preceeding Harvest(Days After Seeding)
Establishment(90d)
NS
CC
B
AA
E D
C
B
D D
C
BA
D C
BA A
A
Tissue K Content
† Within each sampling date, means adjacent to the same letter are not significantly different (α=0.05)
‘Sufficiency level’
†
K Level
1
2
3
4
5
Rate
0.00
0.25
0.50
2.00
3.00
K Treatments
Grey Snow Mold
Tissue K Content (g kg-1)
12 14 16 18 20 22 2450
55
60
65
70
75
80
Mean days to 50% necrosis versus tissue K content at time of inoculation with T. incarnata
Day
s to
50%
Nec
rosi
s (D
ay50
)
r2 = 0.98Pr > F = 0.0009n = 5
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Pink Snow Mold
Tissue K Content (g kg-1)
12 14 16 18 20 22 2470
72
74
76
78
80
82
84
Mean days to 50% necrosis versus tissue K content at time of inoculation with M. nivale
Day
s to
50%
Nec
rosi
s (D
ay50
)
r2 = 0.69Pr > F = 0.08n = 5
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K Research at UMASS:– Gray Snow Mold increased 40% as K rate increased from 1
to 9 lbs/M
Ebdon et al., 2006
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10 20 30 400
2
4
6
8
10
12
14
16
18
20
Tissue K content (g kg-1)
Area
und
er d
isea
se p
rogr
ess c
urve
Critical value = 19.6 g kg-1
R2 = 0.723
From Charles Schmid, Bruce Clarke, Jim Murphy
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Rutgers Anthracnose Data 2012
10 20 30 400
5
10
15
20
25
30
Tissue K content (g kg-1)
Are
a un
der
dise
ase
prog
ress
cu
rve
Critical value = 19.4 g kg-1
R2 = 0.834
Rutgers Anthracnose Data 2013Sponsored by:
From Charles Schmid, Bruce Clarke, Jim Murphy
Soil Test InterpretationTwo main philosophies:
– Sufficiency Level of Available Nutrients (SLAN)• Feed the Plant
– Base Cation Saturation Ratio (BCSR)• Feed the Soil
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• “Ideal” ratios of the major exchangeable cations• CEC central to use of BCSR
Base cation saturation ratioSponsored by:
-
-
-- -
--
---
--
-
--
-
-Mg2+
H+
K+
Cation Exchange Capacity
Ca2+
• The “Ideal” Soil–65 to 85% Ca–6 to 12% Mg–2 to 5% K–Remaining H+, NH4
+
Reasons I Dislike the BCSR Approach1. Ignores differences in nutrient needs among plants
– Genetic aspects– Ecological aspects
2. Scientific literature does not support the claims3. Results in inefficient use of resources
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#1: BCSR Ignores the Plant• Different plants prefer different soil pH• BCSR results in a very narrow range of pH 6.0 – 6.5• Many turf managers attempt to favor bentgrass over annual bluegrass by
modifying root zone pH
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Summary• Potassium is an essential nutrient that plays varied roles in the
plant• Research on how to best manage potassium in turfgrass is
evolving• Evidence for potassium affecting wear tolerance is weak• Potassium plays an important role in drought tolerance, winter
injury, and disease pressure
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Managing Potassium: • Focus on N: K Ratios and Soil Test Levels • N: K2O in the plant is about 1.5 : 1
– Apply 1.5 : 1 to maintain soil K levels when soil K is adequate (according to research-based soil testing guidelines)
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Managing Potassium: • For bentgrass– follow tissue testing for optimum results
– Keep K above 2% in tissue in summer– Allow K to drop to 1.5% or lower in fall
• Keep tissue levels above 2% in situations where snow mold is not a concern.
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What Counts When it Comes to Potassium Source?
Mark Davis, Senior Agronomist
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Considerations When Selecting a K Source
• % K2O• Other nutrients in the fertilizer• Dry or liquid• Salt index• Particle size• Uniformity Index
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The Right Source
Evaluate nutrient content and associated other nutrients
High chloride may be injurious to some crops
Potassium Fertilizers and Salt Index• Salt index provides a relative scale to compare the impact of
fertilizer on soil water • In cases where fertilizer is concentrated, or on salt sensitive crop,
salt index is critical Salt Index
Potassium Fertilizers Salt Index Salt Index/unit of K2O
SOP 46.1 0.88
KNO3 69.5 1.216
MOP 116.2 1.936
KMS 43.2 1.96
KTS 64 2.56
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Salt Tolerance of Common Turf GrassesSalt Impacts• Water imbalance in the Plant,
creating physiological drought• Ion imbalance, increase energy
consumption to maintain metabolic process
• Toxicity from specific ions, Sodium, Chloride and Boron
• Salt impacts plant growth, stunting, darker green leaf color, leaf burn and reduced yields
Grass *Rating
Bermudagrass T
Zoysiagrass MT
Creeping bentgrassMS
Perennial ryegrassMT
Rough bluegrass S
Tall fescue MT
Kentucky bluegrass SAnnual bluegrass
S*T=tolerant, S=sensitive, M=moderately
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Particle Size• Particle size is defined by the size guide number (SGN) value. The
SGN is determined by calculating the average particle size of the product granules in millimeters and multiplying by 100. – Materials and products used on turfgrass generally have an
SGN range of 75 to 350. – Greens products range from 75 to 100, – close cut turf from 125 to 150 and higher – cut turf like lawns 150-240. – SGN is important for fertilizer efficacy because it reflects the
number of particles applied per square inch. Estimated particles per square inch for SGN values of 100, 150, 200, and 240 are 14-16, 8-10, 6-8, and 4-6, respectively
• Make sure your potassium source is sized to the right application and the other fertilizers in the blend
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Uniformity Index (UI)• Uniformity Index (UI) is a value representing the relative particle
size variation of the granules within a product.– A UI of 50 means that the ratio of the smallest particles is one-
half the size of the largest particles. A UI of 100 means that all of the particles within the product are equal in size.
– UI values range from 35 to 60 and a value of 50 is considered acceptable for good uniformity of spread.
– UI is important because with rotary spreader equipment larger granules travel a greater distance than do finer granules.
– A low UI value increases the likelihood of a poor uniformity of spread.
• Make sure your potassium source has a high UI to ensure good spreadability
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Key Facts About CMP’s Protassium+
• CMP is the only North American producer of sulfate of potash.
• Our SOP from the Great Salt Lake is all-natural, produced in OMRI approved organic and non-organic forms.
• Our SOP is virtually chloride free which enhances quality and yield for chloride sensitive crops.
• SOP is a unique dual nutrient, containing both 50% Potassium (K2O) and 17% Sulfur (S).
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Protassium+ (0-0-50-17S)• High K2O analysis 50%
– Cost benefits per unit of nutrients • High S 17%
– Sulfur in the sulfate form, immediate plant available form• Low Cl less than 1%
– Balanced plant nutrition total 67% potassium and sulfur everything you need and nothing you don’t
• Low salt index– Flexibility in application and timing– Safety for the plant and soil systems
• pH neutral– Will not change soil pH or require liming materials over time
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Turf Protassium+ ProductTurf Granular
Suitable for blends used by the turf and ornamental markets. Ideal for roughs and fairways Typical SGN 220/UI 58.
Turf Blend Greens-Grade
SOP Turf Blend™ GREENS-GRADE is best used for micro-sized blends or direct applications on short cut golf greens. Typical SGN 90/UI 59.
Turf Blend Mini-Granular
Ideally suited for mini-size turf blends. Mini-Granular has the highest uniformity index of all the granular SOP's. Mini-Granular can be used on fairways and tees. Typical SGN 140/UI 66.
Soluble Fines
Fine screened for rapid dissolution in making liquid fertilizer solutions and suspensions.
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QUESTIONSThanks for participating!
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