Lawns, Lakes

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Lawns, Lakes, and Laws
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Lawns, Lakes, and Laws

• Phosphorus the element
• Phosphorus and plants and soil
• Phosphorus and lakes
• Sources of urban phosphorus runoff
• Controlling phosphorus runoff

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Issue Over-enrichment of lakes and rivers
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PhosphorusP

• Needed plant nutrient
• Most rare of the major life building
  blocks (C, H, O, N, P, S)
• 75 of nations use is mined in Florida

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PhosphatePO4

• Phosphorus is highly reactive
• Does not exist as an element in nature
• Combines with oxygen to form phosphate

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Phosphorusand plants

• Function Energy transfer and cell division
• Deficiency Stunted growth
• Deficiency Purple or yellow leaves
• Deficiency More common in cool spring

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Phosphorusand plants

• Function Energy transfer and cell division
• Deficiency Stunted growth
• Deficiency Purple or yellow leaves
• Deficiency More common in cool spring

RARE!
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Phosphorus in soil
lt 10 to gt 300 lbs/acre

lt 1 lbs/acre
Pools of phosphorus storage in soil
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Phosphorus in soil

• Soil solution phosphorus (H2PO4-)
• Form taken up by plants
• Mobile form
• Small fraction of total soil P (lt 1 lb/acre)
  

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Phosphorus in soil

• Active soil phosphorus
• In equilibrium with solution P
• lt 10 lbs/acre to gt 300 lbs/acre
• Tightly adhered to soil particles

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Phosphorus and soil pH
7.0 pH
6.0 pH
Availability of phosphorus vs. soil pH
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Phosphorus fertilization

• Recommended on turf when
• Solution P Soil P lt 25 ppm
  
  Bray P1 test

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Phosphorus and lakes

• Most limiting plant nutrient in lakes
• Algae blooms low oxygen and smell
• 1 lbs P 300 lbs to 500 lbs algae

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Impacts of phosphorus
High growth
Low light
Low oxygen
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Speeding aging of lakes
10,000s YEARS IN NATURAL CONDITIONS
10s to 100s YEARS UNDER HUMAN INFLUENCE
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Tropic State
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A factor of 1,000 less!
60 parts per BILLION
30 parts per MILLION
It takes a 1,000 times less phosphorus to turn a
lake green than keep a lawn healthy
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As phosphorus goes up, algae goes up, and water
clarity goes down
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Secchi Disk Secchi disk is a low-tech way to
measure water clarity and determine a lakes
tropic state
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Experimental Lake Area Study(Fisheries and
Oceans Canada)

• Top-to-bottom curtain divides lake in two
• Carbon and nitrogen added to one side
• Carbon, nitrogen and phosphorus added to
  other effect is clear to see

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Sources of phosphorusWhen it rains, it pollutes
Think watersheds!
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Typesof runoff pollution

• Sediment soil erosion, street grit
• Nutrients nitrogen and phosphorus
• Bacteria - wildlife, pets, sewage
• Organics manure, leaves, grass
• Toxics lead, zinc, copper, pesticides

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Impervious surfaces
Residential Areas 50 Impervious
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Every city lot is waterfront property!
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Sources of phosphorus runoff
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Sources of phosphorus runoff from lawns
Soluble plant P
Soil solution P
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Sources of phosphorusrunoff from lawns

• Runoff from plant material (dissolved)
• Misapplied fertilizer (dissolved)
• Runoff from soil solution (dissolved)
• Attached to eroded soil (particulate)

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Sources of phosphorusrunoff from lawns
?

• Runoff from plant material (dissolved)
• Misapplied fertilizer (dissolved)
• Runoff from soil solution (dissolved)
• Attached to eroded soil (particulate)

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Phosphorus runoff by land use
Lbs./Acre/Year Lbs./Acre/Year
Source Soluble P Particulate P
Bare cropland 0.10 33.20
Plowed corn 0.27 13.50
No-till corn 0.98 1.90
Hayland 0.39 0.02
Lawns 0.36 0.00
Sources Sharpley and Menzel 1987 Rehm, 1997, Kussow, 2000. Sources Sharpley and Menzel 1987 Rehm, 1997, Kussow, 2000. Sources Sharpley and Menzel 1987 Rehm, 1997, Kussow, 2000.
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Grass clippings

• Contain 0.13 lbs P / 1000 sq. ft. / year
• Thats 0.65 lbs P / ave. yard / year

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Controlling P runoff is package deal
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Phosphorus fertilization

• MN law restricts P lawn fertilizer use
• Rarely needed on established lawns
• Important when seeding or sodding
• Apply according to soil test

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Reading the bag
Look for the middle number!N - P - K

• Given in phosphate by weight
• Phosphate (P2O5) not phosphorus (P)!
• P P2O5 2.29

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Reading the bag
Look for the zero in middle for phosphorus-free
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Takinga soil test

• The best way to determine P need
• Rare as meteor hits in the metro
• Poor sample technique gives poor results
• Recommended when troubleshooting

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• Sample front and back lawn separately
• Sample randomly, avoid odd areas
• Mix in plastic bucket send 1 pint to lab

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• Two phosphorus tests used in Minnesota based on
  soil pH
• Bray 1 pH 7.4
• Olsen pH gt 7.4

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Application challenges

• Selecting fert. with needed N-P-K balance
• 1,000 sq. ft.??? How big is my lawn?
• Setting spreader application rate
• Soil test? Calibrate? Get a life!!!

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The lawand the lawn

• State phosphorus lawn fertilizer law
• Local fertilizer ordinances
• Use vs. Sale regulation

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Minnesota phosphorus lawn fertilizer law

• First law passed 2002 revised 2004
• Zero P rule goes statewide Jan. 1, 2005
• Concerns phosphorus lawn fertilizer
• Involves use, not sale, of fertilizer
• First in nation - has drawn attention

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MN lawn fertilizer law

• A restriction, not a ban
• 0 P2O5 fertilizer required, unless
• - Newly seeded or sodded lawn
• - Soil test shows need
• - Applied by trained golf course staff

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MN lawn fertilizer law

• When there is need to apply phosphorus,
  University of MN recommendations are to be
  followed
• Law administered by the Minnesota
  Department of Agriculture
• Enforcement by local units of government
  as a petty misdemeanor

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MN lawn fertilizer law
Prohibited to apply fertilizer (any type) to
impervious surfaces. Examples Streets,
sidewalks, driveways. Sweep up over-spread
material.
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MN lawn fertilizer law

• Preempts local ordinances on fertilizer use
• Law does not restrict what stores can sell
  or what customers can buy
• Allows pre-2002 local ordinances on fertilizer
  sales to stand

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City of Burnsville ordinance - before state law

• No application between Nov 15 - April 1
• Clean fertilizer from impervious surfaces
• Keep outside 20 foot buffer around water
• Apply no greater than 0 P2O5 fertilizer
  unless new lawn or soil test shows need
• Notice of law needs to be posted in stores

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City of Burnsville ordinance - after state law

• No application between Nov 15 - April 1
• Clean fertilizer from impervious surfaces
• Keep outside 20 foot buffer around water
• Apply no greater than 0 P2O5 fertilizer
  unless new lawn or soil test shows need
• Notice of law needs to be posted in stores

Locals can no longer regulate fertilizer use
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Publication on the new law 800-877-6300to place
orders
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0 P2O5 fertilizers becoming widely available . .
.
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What to advise . . .

• On existing lawns
• - Use 0 P2O5 fertilizer unless a need
  for phosphorus is shown (soil test)
• - Soil test if lawn if failing to thrive
• - Apply to UM recommendations when
  phosphorus is used

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What to advise . . .

• On new lawns
• - Soil test to 6 depth
• - No test? Apply 2 lbs. P2O5/1,000 sq. ft.
• - Mix fertilizer well into top 6 of soil

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What to advise . . .

• Leftover phosphorus lawn fertilizer
• - In Greater MN, leftover phosphorus
  lawn fertilizer can be used up on lawns
• - In Twin Cities Metro, leftover
  phosphorus lawn fertilizer can be used on
  non-lawn applications (garden)
• - If a lawn fertilizer contains a pesticide,
  it cannot be used for non-lawn use
  dispose as household hazardous waste

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What to advise . . .

• All lawns
• - Sweep up, rake up, pick up
• - Soil test if interested in baseline

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What to advise . . .

• Future? practices to increase infiltration

Rain garden in Burnsville, MN
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www.cleanwatermn.org

• Spring / Fall messages in the media
• Website with resources for citizens,
  cities, and teachers/students
• TV weather broadcast / clean water feature

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Information used
A Primer on Limnology. Bruce Monson. University
of Minnesota Water Resources Center. The Nature
of Phosphorus in Soils. Lowell Busman, et.al.
University of Minnesota Extension Service. Pub.
FO-6795 Phosphorus Transport and Availability in
Surface Waters. Gyles Randall, et.al. U of MN
Extension Service. Pub. FO-6796 Soil Test
Interpretation and Fertilizer Management for
Lawns, Turf, Gardens, and Landscape Plants. Carl
Rosen, et.al. University of Minnesota Extension
Service. Pub. BU-1731 Understanding Lake Data.
Byron Shaw, et.al. University of Wisconsin
Extension. Pub. G3582
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Ron Struss Extension EducatorUniversity of
Minnesota Extension Service 651-480-7708rstruss_at_u
mn.edu