Lawns, Lakes, and Laws

1. Lawns, Lakes, and Laws

2. Lawns, Lakes, and Laws • Phosphorus the element • Phosphorus and plants and soil • Phosphorus and lakes • Sources of urban phosphorus runoff • Controlling phosphorus runoff

4. 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

5. PhosphatePO4 • Phosphorus is highly reactive • Does not exist as an element in nature • Combines with oxygen to form phosphate

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

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

8. ActiveSoilP SoilSolutionP Phosphorus in soil < 10 to > 300 lbs/acre < 1 lbs/acre “Pools” of phosphorus storage in soil

9. 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)

10. 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

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

12. Phosphorus fertilization • Recommended on turf when: • Solution P + Soil P < 25 ppm

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

14. Impacts of phosphorus High growth Low light Low oxygen

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

16. (ppb) Tropic State

17. 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

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

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

20. 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

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

22. 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

23. Impervious surfaces Residential Areas = 50% Impervious

24. Every city lot is waterfront property!

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

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

27. LIKELYHOOD Sources of phosphorusrunoff from lawns • Runoff from plant material (dissolved) • Misapplied fertilizer (dissolved) • Runoff from soil solution (dissolved) • Attached to eroded soil (particulate)

28. LIKELYHOOD Sources of phosphorusrunoff from lawns ? • Runoff from plant material (dissolved) • Misapplied fertilizer (dissolved) • Runoff from soil solution (dissolved) • Attached to eroded soil (particulate)

29. SOIL EROSION Phosphorus runoff by land use

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

31. Controlling “P” runoff is package deal

32. How much “P” comes from leaves? • 0.003 to 0.007lbs P / hardwood / year • If half the leaves from boulevard trees hit the street, a city block can produce 0.05 to 0.10 lbs P / year in runoff

33. Phosphorus fertilization • Apply according to soil test • Important when seeding or sodding • Rarely needed on est. lawns in Metro • Sweep up overspread & spilled material

34. 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

35. 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”

36. 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!!!

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

38. Minnesota phosphorus lawn fertilizer law • Passed in 2002 • Goes into full effect in 2004 • Concerns phosphorus fertilizer - mostly • Treats metro and non-metro differently • First in nation - has drawn attention

39. MN lawn fertilizer law • Metro area (seven county) - Starts 2004 • 0% P2O5 fertilizer required, unless: • - Newly seeded or sodded lawn • - Soil test shows need • - Applied by trained golf course staff

40. MN lawn fertilizer law • Non-metro area - Starts 2004 • No greater than 3% P2O5 fertilizer required, unless: • - Newly seeded or sodded lawn • - Soil test shows need • - Applied by certified golf course staff • Cities can opt to adopt 0% P2O5 limit

41. MN lawn fertilizer law • When liquid product is used in non-metro area, rate is limited to 0.3 lbs. P2O5 per 1,000 sq. ft. - unless need for higher rates is shown. • When there is need to apply phosphorus lawn fertilizer at higher rates, University of Minnesota recommendations are to be followed.

42. MN lawn fertilizer law Prohibited to apply fertilizer (any type) to impervious surfaces. Examples: Streets, sidewalks, driveways. Started 2002

43. MN lawn fertilizer law • Preempts local ordinances on fertilizer use • Allows pre-2002 local ordinances on fertilizer sales to stand • Enforcement by local units of government as a petty misdemeanor

44. 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

45. 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

46. Publication on the new law 800-877-6300to place orders

47. 0% P2O5 fertilizers becoming widely available . . .

48. 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

49. 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

50. What to advise . . . • All lawns • - Sweep up, rake up, pick up • - Soil test if interested in “baseline”