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Keys to Sustainable Lawn Care in Nebraska
Bill Kreuser
http://turf.unl.edu/
What is Sustainable Lawn Care?
• No inputs
– Lawns can’t exist without some maintenance
• Organic products and fertilizers
– Possible but know definition of “organic” in industry
– Not always better/safer/legal
• Minimizing inputs
– Less fertilizer/water/pesticides
– Changing expectations……
ExpectationsLawns Require A Lot of Energy
• Physical Energy
• Chemical Energy– Gasoline for equipment
– Manufacture of pesticides and fertilizer
– Energy to pump water
Lawns are great carbon banks
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What is Thatch?
Slowly Decaying Plant Tissues
• Stems
• Dead crowns
• Leaf Sheaths
Not clippings and roots
Highly Lignified Tissue
Why is Thatch a Problem
• Turfgrass crowns are exposed to elements
• Harbor pests
• Reduced water infiltration
• Easy to scalp during mowing
• Nothing good about TOO much thatch
Keys to Sustainable Best Management Practices for an Above Average Lawn
1. Plant the correct grass/plant
2. Mow correctly
3. Precisely manage water and nutrient applications
4. Manage soil
5. Use pesticides as last resort!
Plant the Correct Grass
• Mostly cool-season turf in NE
– Creeping: Kentucky bluegrass
– Bunch type: Tall fescue, perennial ryegrass
• Warm season exception
– Buffalograss
• Native to the Great Plains
• Creeping type grass
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Kentucky bluegrass• Fine leaf texture and mid to
dark green color
• Spreads by lateral stems in the soil called rhizomes
• Average root system and water use (ET)
• Goes dormant during drought
• Good for cool/arid climates (Western NE)
Common Kentucky Bluegrass
Elite/Improved Kentucky Bluegrass Premium Kentucky Bluegrass
0 Fert Apps 4 Fert Apps
3.5 Inch HOC
2.5 inch HOC
Turf Type Tall Fescue• Dark green color with course
to medium-fine texture
• Good heat tolerance
• Deep rooting turf but highest water use
• Great for locations with temporary (short-term) drought
• Eastern NE, but exploring suitability in further west
Tall Fescue
4 Fert Apps 0 Fert Apps 2 Fert Apps
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Perennial Ryegrass
• Fine texture and shiny dark green leaf
• Quick to establish
• Poor to moderate drought tolerance and avoidance
• Susceptible to summer diseases/insects
• Killed by extreme temperatures
Perennial Ryegrass
0 Fert Apps 4 Fert Apps 2 Fert Apps
Buffalograss
• Native to Great Plains
• Light green color and fine texture
• Warm-season grass (grows during summer
• Deep rooting + low water use
• Low (not no) maintenance
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Sometimes Grass isn’t the Anwser
Questions
Keys to Sustainable Best Management Practices for an Above Average Lawn
1. Plant the correct grass/plant
2. Mow correctly
3. Precisely manage water and nutrient applications
4. Manage soil
5. Use pesticides as last resort!
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Benefits of Mowing
• Appearance
• Increase leaf density
• Remove damaged leaves
• Prevents seed heads from forming
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Does Mowing Height and Frequency Affect Growth Rate
Different Rationales:
1) Frequent mowing increases turfgrass growth rate because it is less stressful than scalping
2) Scalping cause the growth to grow slower and reduces mowing requirements
3) Mowing to the 1/3 rule is best for healthy turf while providing the minimal amounts of mowing
Designed a Tall Fescue Mowing StudyTreatments:
• Height of cut (2” or 3”)
• Frequency of Cut (weekly, ¼ rule, 1/3 rule, ½ rule)
Controls
• Never fertilized during the year and watered to 80% of pET nightly
Measured clipping yield and turf quality all summer
Explaining Mowing Frequencies
2" 3"
Weekly - -
1/4 Rule 2.66 4
1/3 Rule 3 4.5
1/2 Rule 4 6
3”½ Rule Weekly ¼ Rule 1/3 Rule
block 1
2”½ Rule Weekly ¼ Rule 1/3 Rule
2”¼ Rule Weekly 1/3 Rule ½ Rule
block 2
3”¼ Rule Weekly 1/3 Rule ½ Rule
2”½ Rule 1/3 Rule Weekly ¼ Rule
block 3
3”½ Rule 1/3 Rule Weekly ¼ Rule
At End of Season, Mowed All Plots to 2” or 3” and calculated total clipping
production
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First Year Results
No ScalpingGood Quality
No ScalpingGood Quality
Cumulative Clippings Over Time
Mowing Best Management Practices
• Mow at 2 to 3 inches
– Higher to keep out weeds
– Reduced water use
• Mow to 1/3 rule: 3 to 4.5 inches
– Reduces number of total mowings
– Keeps turf healthy and dense
– Doesn’t scalp the turf
• Return clippings!
Questions
Keys to Sustainable Best Management Practices for an Above Average Lawn
1. Plant the correct grass/plant
2. Mow correctly
3. Precisely manage water and nutrient applications
4. Manage soil
5. Use pesticides as last resort!
Why do we water?
2% for Metabolism
98% for Cooling
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Large Differences in Annual Precip
Annual Precip < Water Loss All Plants Resist Drought Stress
Drought Avoidance Drought Tolerance
Plant Response to Drought
• Stomata Close
• Leaf growth slows
• Root growth increases
• Cell division slows
• Cells accumulate sugars
• Leaves and roots die
• Cells break/die
• Plant dies
Short Drought
Prolonged Drought
Minutes
Days
Weeks
Months
Season
Turf Needs Water
• Precision Water Management Key
–Know How Much is Required
–Monitor Soil Moisture
–Proper Placement
–Uniformity in Soil
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Irrigation Basics
• Amount and frequency change throughout the growing season
Under-Irrigation
Wilt
Insufficient Rootzone Moisture(under-watering)
• Slow growth (recuperative potential)
• Wilt
• Hard surface
• Susceptible to insect pests
Brown patch
Thatch accumulation
Excessive Irrigation
Excessive Irrigation
Algae / moss
Poa annua
• Leaching
• Anerobic soil
• Shallow rooting
• Denitrification
• Thatch accumulation
• Algae
• Moss
• Black layer
• Poor stress tolerance
• Poor quality playing surface (rutting, divoting)
• Poor shear strength
• Disease (pythium blight, brown patch, etc…)
• Waste of water ($$$$$)
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How much water is lost?• Evapotranspiration (ET) is the amount of water
lost from soil evaporation and transpiration
– Parameters?
• Directly measure ET
• Estimate potential ET
– Satellite data
http://www.hprcc.unl.edu/awdn/maps
Don’t Water to 100% pET
• Crop coefficients (Kc) available for turf
– Cool-season turf 60 to 80% of pET
– Warm-season 40 to 60% pET
– Can be much lower…
• Deficit Irrigation works when there is occasional rain
Homeowner Irrigation BMP
Turn off the irrigation systems
When you see drought symptoms then turn on the
irrigation
Apply an inch of water
Turn System Back Off
Monitor Soil Moisture
TDR Probe
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0
10
20
30
40
50
60
70
80
June July August September
TN
C i
n t
urf
gra
ss r
oo
ts(m
g g
-1)
Light & frequent
Deep & infrequent
Moderate Drought Stress Increases Plant Health
Fu, J., and P. H. Dernoeden. 2008. Carbohydrate metabolism in creeping bentgrass as influenced by two summer irrigation
practices. J. Am. Soc. Hortic. Sci. 133(5):p. 678-683.
Deficit Irrigation
• Keeps things consistently dry
• Uses less irrigation
• Reduces nutrient and pesticides leaching
• Requires closer monitoring
Optimize irrigation applications
• Check your systems
– Nozzle wear and uneven heads
– Minutes vs inches
• Monitor soil moisture
• Adjust run times and change nozzles
• Recognize wilt and then water
Irrigation Distribution Uniformity
Minutes vs. Inches
There is no universal amount of water to apply
Questions
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Why Fertilize Turf?
• Qualitative Reasons
– Color
– Leaf density
– Recover from traffic
– Recover from environmental stress
• Replace nutrients as they become unavailable
– Leaching, volatilization, runoff, removal
– Fixation and Immobilization
The Essential Nutrients
Primary & Secondary
• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)
% N - % P2O5 - % K2O
• Calcium (Ca)
• Magnesium (Mg)
• Sulfur (S)
Micronutrients
• Iron (Fe)
• Manganese (Mn)
• Molybdenum (Mo)
• Zinc (Zn)
• Boron (B)
• Chlorine (Cl)
• Copper (Cu)
• Nickel (Ni)
Silicon???
All Nutrients Are Important
• Turfgrass growth controlled by the most limiting nutrient
• Nitrogen almost always the limiting nutrient
Nitro
gen
We Don’t Maximize Yield Like a Crop
0
50
100
150
200
250
300
350
400
450
0 2 4 6 8 10 12 14 16
Cli
pp
ings
lb/M
N Rate lb/M/yr
Low N High N
How Much Nitrogen to Apply?
• Yield unimportant
• Depends on turfgrass application
– Performance
– Quality
• Current recommendations are historical
Goldilocks Method
Too much Nitrogen
• Reduced root growth
– Decreases stress tolerance - esp. water
• Excessive thatch development
• Increased mowing requirement
• Increases incidence of many diseases
– brown patch, snow mold, gray leaf spot, take-all patch
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Not Enough Nitrogen
• Reduced shoot density– Increased weed invasion – esp. clover and
crabgrass
– Increased reliance on pesticides
– May need to completely renovate if weeds win
• Unsafe playing conditions
• Unattractive
• Increases incidence of certain diseases– Rust, red thread, dollar spot
Just Right Nitrogen
• Good green color
• Moderate growth rate
• Optimum tolerance to environmental stresses
• High shoot density but vigorous root system
• Good recuperative potential
• Poor turfgrass performance (putting greens)
Turfgrass N Cycle
Mineral Nitrogen (NH4
+, NO3-, NO2
-)Organic Nitrogen Complex structure
Immobilization(Plant & Microbe Uptake)
Mineralization
Microbe DependentLeaching & Runoff
Denitrification & Volatilization
Clipping Removal &
Aeration
AtmosphericDepositionFixation
Fertilizer
OM accumulates as turf ages
Source: Gaussoin and Shearman, 2003; Gaussoin et al., 2006
Soil OM increases with time – Adds fertility
Qian et al., 2003
N uptake from fert (~1#/M)
N uptake from soil (~1#/M)
N uptake from clippings (~1#/M)
From a well established lawn area
Starr and DeRoo, 1981
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Slow SOM build-up reduces N requirements
Frank et al., 2006
MSU Monmouth Lysimeters
Nitrogen leaching from over-fertilizing established turfNitrogen Fertilization BMPS
• Amount of N required changes as turf ages
– New lawn
• 2-6 applications a year
– Established lawn
• 0-3 applications a year
– Kentucky bluegrass and perennial ryegrass need more than tall fescue or buffalograss
• Timing critical
Average Fertility Requirements
Grass Species Average Lawn High Maintenance
lbs N/1000 ft2
Kentuckybluegrass
1-4* 2-6
Perennial ryegrass
2-5 2-6
Tall fescue 0-2 2-4
Fine fescue 0-2 1-3
Buffalograss 0-2 0-2
When to apply fertilizer• Cool-season turf
1. Late summer (Aug-September)
• Balanced N source (50% WSN 50% WISN)
2. Mid-spring (Late April)
• After initial spring growth surge (balanced source)
3. Mid-summer (June)
• Slow release or organic nitrogen (WISN)
• Water in and don’t apply to drought stress turf
4. Mid-fall (mid-October)
1. Quick release (WSN)
2. Not too late….recommendation has changed
When to apply fertilizer• Warm-season turf
1. Early summer (May to June)
2. Mid-summer (July to early Aug)
• Balanced nitrogen source
• Water in and be careful during drought periods
Soil Test for Other Essential Nutrients
• Estimate plant available nutrients
• Monitor changes in soil nutrients
• Peace of Mind
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-
-
-- -
--
--
-
--
-
--
-
-
Mg2+
H+
K+
Cation Exchange Capacity
Ca2+ We Can Test for Everything but N
Primary & Secondary
• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)
• Calcium (Ca)
• Magnesium (Mg)
• Sulfur (S)
Micronutrients
• Iron (Fe)
• Manganese (Mn)
• Molybdenum (Mo)
• Zinc (Zn)
• Boron (B)
• Chlorine (Cl)
• Copper (Cu)
• Nickel (Ni)
Proper Sampling Collecting a Representative Sample• Take a Composite
Representative Sample
• Consistent Sampling Depth and Time of Year
• Consistent Soil Testing Lab or Method
Proper Sampling
• Representative Areas–Mineral soils vs. sand or constructed soils
–Areas built at different times
–Areas cut out of forest vs. old agricultural land
–Areas of drastically different soil type
Where the roots are
How Deep?
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How Deep?
DepthMehlich 3
Phosphorus
Inches ppm
0 – 1 205
0 – 2 138
0 – 6 74
33% decrease in
soil P with addition
of 1 inch of soil!
Keys to Consistent Soil Testing
When: Early Spring
Where: Representative soil areas
How Deep: Be consistent, 4” good depth
Which Lab: Use same lab you trust always
Micronutrients: Who cares – tissue testing best
Need to be consistent to monitor changes over time!!
Great Fertilizer Grade Diversity
Blended Fertilizers
• Mixture of fertilizer sources
– Nutrient release character release
– Addition of other nutrients
• Suited to address different turf requirements
– Starter (high P2O5)
– Winterizer (higher K2O)
– Micronutrients additions
• What’s the ideal fertilizer ratio for turfgrass?
Plants Control Nutrient Uptake NotTurf Managers
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Fertilizing Soils With Sufficient Nutrients Does Not Affect Turf
4.3 4.3 4.3 4.3
0.44 0.44 0.42 0.43
2.5 2.6 2.6 2.6
0
1
2
3
4
5
4-0-0 4-1-0 4-0-3 4-1-3
Tiss
ue
Co
nte
nt
(% d
ry w
eig
ht)
Pounds of N-P2O5-K2O Fertilizer Applied Annually to 1000 ft2
Leaf N
Leaf P
Leaf K
62ppm Soil Test Phosphorus 180ppm Soil Test Potassium
N drives uptake of other nutrients
3.8
4.3
5.2
0.42 0.44 0.48
2.42.6
2.9
0
1
2
3
4
5
6
2 4 6
Tiss
ue
Co
nte
nt
(% d
ry w
eig
ht)
Annual Nitrogen Fertilization Rate (lbs/1000 ft2)
Leaf N
Leaf P
Leaf K
Fertilizer Ratio: 5-1-2Soil Test P: 62ppmSoil Test K: 180ppm
1-0-0 – The Ideal Fertilizer Ratio?
• Nitrogen-only fertilization can be very effective
• Gradual decline in other soil test nutrients levels with N only fertilization
• Treat the soil like a nutrient bank account
Nutrient Losses = Fertilizer Additions
5-1-2 Ratio Changed Soil Test Levels
6
10
17
25
37
57
0
10
20
30
40
50
60
2 4 6
Ch
ange
in S
oil
Test
Lev
els
(Th
ree
Year
s p
pm
)
Annual Nitrogen Fertilization Rate (lbs/1000 ft2)
Soil Test P
Soil Test K
Fertilizer Ratio: 5-1-2Soil Test P: 62ppmSoil Test K: 180ppm
Approximate* Ideal Fertilization Ratios
Grass Species Root Zone Soil Mowing Clipping
Management
Annual Ideal
Fertilizer Ratio
Cool-season lawn and
athletic field species
(Kentucky bluegrass,
perennial ryegrass)
Native soil Clippings Removed 4-1-3
Clippings Returned 8-1-4
Sand-based soil Clippings Removed 4-1-4
Clippings Returned 8-1-8
Creeping bentgrass
turf
Native soil Clippings Removed 4-1-3
Clippings Returned 6-1-4
Sand-based soil Clippings Removed 4-1-4
Clippings Returned 6-1-6
* Actual ideal fertilizer ratio varies depending on local environment (soil, precip, ect.)
Questions??
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Keys to Sustainable Best Management Practices for an Above Average Lawn
1. Plant the correct grass/plant
2. Mow correctly
3. Precisely manage water and nutrient applications
4. Manage soil
5. Use pesticides as last resort!
What is Thatch?
Slowly Decaying Plant Tissues
• Stems
• Dead crowns
• Leaf Sheaths
Not clippings and roots
Highly Lignified Tissue
Thatch Management Strategies
• Species Selection
• Nitrogen Fertilization
• Mechanical Removal
• Renovation
pH modification, avoid pesticides, inoculate with
microbes
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Differences in Species and Variety
Higher Thatch Potential
• Kentucky bluegrass
• Fine fescue
• Roughstalk bluegrass
• Improved varieties
Lower Thatch Potential
• Perennial ryegrass
• Tall fescue
• Older common varieties
Implications for Management
Mechanical RemovalCore Aeration Dethatcher – Power Rake
Manual Raking Fun
Aeration Impact Tine Size and Surface Area Chart
Tine Size
(in.)
Spacing
(in.)
Holes/ft2
Surface
Area
of One
Tine
Percent
Surface
Area
Affected
1/4 1.252 100 0.049 3.4%
1/4 2.52 25 0.049 0.9%
1/2 1.252 100 0.196 13.6%
1/2 2.52 25 0.196 3.4%
5/8 2.52 25 3.07 5.3%
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Still Benefits to Aeration
• Increased water infiltration
• Cores dilute some thatch as topdressing
• Increased soil aeration
• Reduced soil compaction
Timing Thatch Removal
Avoid Early Spring, Mid-Summer, and Late Fall Power Raking
Dilution Can Be the Solution
• Topdressing buries thatch
• Enhances microbial breakdown
• Materials
– Sand
– Compost
Extreme Thatch Accumulation Call for Complete Renovation Turf.unl.edu
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Best Management Practices for an Above Average Lawn in Central NE
1. Plant Tall Fescue or Buffalograss
2. Mow grass to 3” when it reaches 4.5”
3. Water deeply when drought stress is visible
4. Fertilize when grass looks yellow (late spring and early fall)
5. Manage water and fertilizer to limit thatch; remove in spring
6. Use pesticides as last resort!
Bill [email protected]://turf.unl.edu/
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