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

3. Issue: Over-enrichment of lakes and rivers

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** Bray P1 test

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

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

33. 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

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

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 • 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

39. 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

40. 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

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

42. 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

43. 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

44. 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

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

46. 0% P2O5 fertilizers becoming widely available . . .

47. 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

48. 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

49. 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

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