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

Phosphate PO 4 Phosphorus is highly reactive Does not exist as an element in nature Does not exist as an element in nature Combines with oxygen to form phosphate Combines with oxygen to form phosphate

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

Phosphorus and plants Function:Energy transfer and cell division Function: Energy transfer and cell division Deficiency: Stunted growth Deficiency: Stunted growth Deficiency: Purple or yellow leaves Deficiency: Purple or yellow leaves Deficiency: More common in cool spring Deficiency: More common in cool spring RARE!

Phosphorus in soil “Pools” of phosphorus storage in soil 300 lbs/acre 300 lbs/acre < 1 lbs/acre Active Soil P Soil Solution P

Soil solution phosphorus (H 2 PO 4 - )Soil solution phosphorus (H 2 PO 4 - ) –Form taken up by plants –Mobile form –Small fraction of total soil P (< 1 lb/acre) Phosphorus in soil Active Soil P Soil Solution P

Active soil phosphorus Active soil phosphorus – In equilibrium with solution P – 300 lbs/acre – Tightly adhered to soil particles Active Soil P Soil Solution P Phosphorus in soil

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

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

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

High growth Low light Low oxygen Impacts of phosphorus

10,000’s YEARS IN NATURAL CONDITIONS 10’s to 100’s YEARS UNDER HUMAN INFLUENCE Speeding aging of lakes

Tropic State (ppb)

A factor of 1,000 less! It takes a 1,000 times less phosphorus to turn a lake green than keep a lawn healthy 60 parts per BILLION 30 parts per MILLION

As phosphorus goes up, algae goes up, and water clarity goes down

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

Experimental Lake Area Study (Fisheries and Oceans Canada) Top-to-bottom curtain divides lake in two Carbon and nitrogen added to one side Carbon and nitrogen added to one side Carbon, nitrogen and phosphorus added to other – effect is clear to see Carbon, nitrogen and phosphorus added to other – effect is clear to see

Sources of phosphorus “When it rains, it pollutes” Think watersheds!

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

Impervious surfaces Residential Areas = 50% Impervious

Every city lot is waterfront property!

Sources of phosphorus runoff Streets Lawns Driveways Roofs Sidewalks Bannerman - Wisconsin DNR

Soluble plant P Soil solution P Soil particle P Product Sources of phosphorus runoff from lawns

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

Sources of phosphorus runoff from lawns Runoff from plant material (dissolved) Runoff from plant material (dissolved) Misapplied fertilizer (dissolved) Misapplied fertilizer (dissolved) Runoff from soil solution (dissolved) Runoff from soil solution (dissolved) Attached to eroded soil (particulate) Attached to eroded soil (particulate) LIKELYHOOD ?

Lbs./Acre/Year Source Source Soluble P Particulate P Bare cropland Bare cropland Plowed corn Plowed corn No-till corn No-till corn Hayland Hayland Lawns Lawns Sources: Sharpley and Menzel 1987; Rehm, 1997, Kussow, Sources: Sharpley and Menzel 1987; Rehm, 1997, Kussow, Phosphorus runoff by land use SOIL EROSION

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

Controlling “P” runoff is package deal

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

Reading the bag Given in % phosphate by weight Phosphate (P 2 O 5 ) not phosphorus (P)! Phosphate (P 2 O 5 ) not phosphorus (P)! P = P 2 O 5 ÷ 2.29 P = P 2 O 5 ÷ 2.29 Look for the middle number! N - P - K

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

The best way to determine P need The best way to determine P need Rare as meteor hits in the metro Rare as meteor hits in the metro Poor sample technique gives poor results Poor sample technique gives poor results Recommended when “troubleshooting” Recommended when “troubleshooting” Taking a soil test

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

Two phosphorus tests used in Minnesota based on soil pH: – Bray 1 – pH ≤ 7.4 – Olsen – pH > 7.4

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

State phosphorus lawn fertilizer law State phosphorus lawn fertilizer law Local fertilizer ordinances Local fertilizer ordinances “Use” vs. “Sale” regulation “Use” vs. “Sale” regulation The law and the lawn

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

MN lawn fertilizer law A restriction, not a ban: 0% P 2 O 5 fertilizer required, unless: 0% P 2 O 5 fertilizer required, unless: - Newly seeded or sodded lawn - Newly seeded or sodded lawn - Soil test shows need - Soil test shows need - Applied by trained golf course staff

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

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

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

City of Burnsville ordinance - before state law No application between Nov 15 - April 1 No application between Nov 15 - April 1 Clean fertilizer from impervious surfaces Clean fertilizer from impervious surfaces Keep outside 20 foot buffer around water Keep outside 20 foot buffer around water Apply no greater than 0% P 2 O 5 fertilizer unless new lawn or soil test shows need Apply no greater than 0% P 2 O 5 fertilizer unless new lawn or soil test shows need Notice of law needs to be posted in stores Notice of law needs to be posted in stores

City of Burnsville ordinance - after state law No application between Nov 15 - April 1 No application between Nov 15 - April 1 Clean fertilizer from impervious surfaces Clean fertilizer from impervious surfaces Keep outside 20 foot buffer around water Keep outside 20 foot buffer around water Apply no greater than 0% P 2 O 5 fertilizer unless new lawn or soil test shows need Apply no greater than 0% P 2 O 5 fertilizer unless new lawn or soil test shows need Notice of law needs to be posted in stores Notice of law needs to be posted in stores Locals can no longer regulate fertilizer use

Publication on the new law to place orders

0% P 2 O 5 fertilizers becoming widely available...

On existing lawns On existing lawns - Use 0% P 2 O 5 fertilizer unless a need for phosphorus is shown (soil test) - Use 0% P 2 O 5 fertilizer unless a need for phosphorus is shown (soil test) - Soil test if lawn if failing to thrive - Soil test if lawn if failing to thrive - Apply to UM recommendations when phosphorus is used - Apply to UM recommendations when phosphorus is used What to advise...

On new lawns On new lawns - Soil test to 6” depth - Soil test to 6” depth - No test? Apply 2 lbs. P 2 O 5 /1,000 sq. ft. - No test? Apply 2 lbs. P 2 O 5 /1,000 sq. ft. - Mix fertilizer well into top 6” of soil - Mix fertilizer well into top 6” of soil What to advise...

Leftover phosphorus lawn fertilizer Leftover phosphorus lawn fertilizer - In Greater MN, leftover phosphorus lawn fertilizer can be used up on lawns - 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) - 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 - If a lawn fertilizer contains a pesticide, it cannot be used for non-lawn use – dispose as household hazardous waste What to advise...

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

What to advise... Future? – practices to increase infiltration Rain garden in Burnsville, MN

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

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

Ron Struss Extension Educator University of Minnesota Extension Service