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Lawns, Lakes, and Laws. Lawns, Lakes, and Laws. Phosphorus the element Phosphorus and plants and soil Phosphorus and lakes Sources of urban phosphorus runoff Controlling phosphorus runoff. Issue: Over-enrichment of lakes and rivers. Phosphorus “P”. Needed plant nutrient

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Presentation Transcript
slide2

Lawns, Lakes, and Laws

  • Phosphorus the element
  • Phosphorus and plants and soil
  • Phosphorus and lakes
  • Sources of urban phosphorus runoff
  • Controlling phosphorus runoff
slide4

Phosphorus“P”

  • Needed plant nutrient
  • Most rare of the major “life building blocks” (C, H, O, N, P, S)
  • 75% of nation’s use is mined in Florida
slide5

PhosphatePO4

  • Phosphorus is highly reactive
  • Does not exist as an element in nature
  • Combines with oxygen to form phosphate
slide6

Phosphorusand plants

  • Function:Energy transfer and cell division
  • Deficiency: Stunted growth
  • Deficiency: Purple or yellow leaves
  • Deficiency: More common in cool spring
slide7

Phosphorusand plants

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

RARE!

slide8

ActiveSoilP

SoilSolutionP

Phosphorus in soil

< 10 to > 300 lbs/acre

< 1 lbs/acre

“Pools” of phosphorus storage in soil

slide9

ActiveSoilP

SoilSolutionP

Phosphorus in soil

  • Soil solution phosphorus (H2PO4-)
    • Form taken up by plants
    • Mobile form
    • Small fraction of total soil P (< 1 lb/acre)
slide10

ActiveSoilP

SoilSolutionP

Phosphorus in soil

  • Active soil phosphorus
    • In equilibrium with solution P
    • < 10 lbs/acre to > 300 lbs/acre
    • Tightly adhered to soil particles
slide11

Phosphorus and soil pH

7.0 pH

6.0 pH

Availability of phosphorus vs. soil pH

slide12

Phosphorus fertilization

  • Recommended on turf when:
  • Solution P + Soil P < 25 ppm** Bray P1 test
slide13

Phosphorus and lakes

  • Most limiting plant nutrient in lakes
  • Algae “blooms” = low oxygen and smell
  • 1 lbs P = 300 lbs to 500 lbs algae
slide14

Impacts of phosphorus

High growth

Low light

Low oxygen

slide15

Speeding aging of lakes

10,000’s YEARS IN NATURAL CONDITIONS

10’s to 100’s YEARS UNDER HUMAN INFLUENCE

slide16

(ppb)

Tropic State

slide17

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

slide19

Secchi Disk

Secchi disk is a low-tech way to measure water clarity and determine a lake’s tropic state

slide20

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
slide22

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
slide23

Impervious surfaces

Residential Areas = 50% Impervious

slide25

Bannerman - Wisconsin DNR

Roofs

Sidewalks

Driveways

Streets

Lawns

Sources of phosphorus runoff

slide26

Soil particle P

Product

Sources of phosphorus runoff from lawns

Soluble plant P

Soil solution P

slide27

LIKELYHOOD

Sources of phosphorusrunoff from lawns

  • Runoff from plant material (dissolved)
  • Misapplied fertilizer (dissolved)
  • Runoff from soil solution (dissolved)
  • Attached to eroded soil (particulate)
slide28

LIKELYHOOD

Sources of phosphorusrunoff from lawns

?

  • Runoff from plant material (dissolved)
  • Misapplied fertilizer (dissolved)
  • Runoff from soil solution (dissolved)
  • Attached to eroded soil (particulate)
slide29

SOIL EROSION

Phosphorus runoff by land use

slide30

Grass clippings

  • Contain 0.13 lbs P / 1000 sq. ft. / year
  • That’s 0.65 lbs P / ave. yard / year
slide32

Phosphorus fertilization

  • MN law restricts P lawn fertilizer use
  • Rarely needed on established lawns
  • Important when seeding or sodding
  • Apply according to soil test
slide33

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
slide34

Reading the bag

Look for “the zero in middle” for phosphorus-free

slide35

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”
slide36

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!!!
slide37

The lawand the lawn

  • State phosphorus lawn fertilizer law
  • Local fertilizer ordinances
  • “Use” vs. “Sale” regulation
slide38

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
slide39

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
slide40

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
slide41

MN lawn fertilizer law

Prohibited to apply fertilizer (any type) to impervious surfaces.

Examples: Streets, sidewalks, driveways.

Sweep up over-spread material.

slide42

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
slide43

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
slide44

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

slide45

Publication on the new law

800-877-6300to place orders

slide47

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
slide48

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
slide49

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
slide50

What to advise . . .

  • All lawns
  • - Sweep up, rake up, pick up
  • - Soil test if interested in “baseline”
slide52

What to advise . . .

  • Future? – practices to increase infiltration

Rain garden in Burnsville, MN

slide53

www.cleanwatermn.org

  • Spring / Fall messages in the media
  • Website with resources for citizens, cities, and teachers/students
  • TV weather broadcast / clean water feature
slide55

Ron Struss

Extension EducatorUniversity of Minnesota Extension Service

651-480-7708rstruss@umn.edu