Phosphorus is an essential nutrient for plants that is often limited in soils. In South Florida, phosphorus loading from agricultural production, urban development, and altered hydrology has negatively impacted the Everglades ecosystem. Draining of wetlands for agriculture exposed organic soils to oxygen, accelerating decomposition and loss of soil. Restoration efforts aim to reduce phosphorus inputs and restore more natural water flows to improve water quality and habitat in the Everglades.
4. Fertility
10 -15% of applied fertilizer phosphorous used by plants
85 – 90% is bound to soil particles or forms insoluble solids
=>excess application
=>saturation of soil capacity
=> mobility in the environment
-Total soil phosphorous is low
-Most of the total is unavailable to plants
-Much of soil P forms insoluble solids
(limiting to availability)
12. Calcium Binding in Basic Soils
CaCO3
CaCO3 + 2H2(PO4)- = Ca [H2(PO4)]2 + CO3
2-
CaHPO4
Ca5(PO4)3OH (Apatite mineral)
(higher calcium availability)
H2(PO4)- is the available form of P
13. Availability and pH
Low pH High pH
Aluminum and Iron
phosphates
Calcium Phosphates
Formation of insoluble solids
15. Fixation on Iron and Aluminum
A dominant interaction between Phosphorus and
soils is strong interaction with Iron and Aluminum Oxides
Al
Al
OH
OH
OH
Fe
Fe
OH
OH
OH
18. Coatings on Sands and Silicate Clays
Fe coating
Fe
Fe
OH
OH
H2(PO4)-
19. Organic Matter
Organic matter does not typically
bind strongly with phosphorus.
Organic matter covers fixation sites
Organic matter reacts with free Fe and Al
Organic matter competes for anion exch. sites
Organic Matter tends to increase P availability
20. -Plant Available
-Fe, Al bound
-Calcium bound
- Fixed on oxides
H2PO4
- HPO4
-2
Al(PO4) • H2O
Ca3(PO4)2
H2PO4
-
Inorganic Soil Phosphorous
Inorganic
(low)
Phosphorus is generally removed from solution by soil processes
These processes have a finite capacity to retain phosphorus
When the capacity is exceeded, phosphorus can become mobile.
22. Historic flow patterns in the
Kissimmee – Okeechobee – Everglades
system has been significantly altered,
beginning in the late 1800’s.
The design was to drain significant
areas for agriculture and development
and to prevent floodwaters from
communities to the south and east.
Historic Flow Patterns
Okeechobee and the Everglades
24. "The first and most abiding
impression is the utter
worthlessness
to civilized man, in its
present condition, of the
entire region."
Buckingham Smith
1835
First Survey
In 1850, the Swamplands Act Passed
Population: 87,445
Transferred 20 million aces to FL for drainage and reclamation
25. 11 miles (17.7 km) of
canal south of Lake
Okeechobee towards
Miami.
1881
Hamilton Disston
50,000 acres drained
Okeechobee north to Kissimmee
and west to the Gulf of Mexico.
32. 143 miles of levee
45 feet high and 150 feet wide
After the storm
Hoover Dike
19 water control structures
33. Hoover Dike (1932)
Everglades Agricultural Area (EAA)
Perimeter Levee (1954)
Water Conservation Areas
(management of flow)
Former extent of Kissimmee
Basin and floodplain
To Gulf
To Atlantic
Drainage
37. 1940’s thousands of acres converted to agricultural production
1959 Cuban exiles established sugar plantations
1960s Sugar production increased 4-fold
Today, sugarcane production contributes
two-thirds of the economic production of
Everglades agriculture, and uses nearly
80% of the crop land in the EAA
Sugar and vegetable production
contributes phosphorus
to the ecosystem primarily through
fertilizers and to a lesser extent through
decomposition of plants.
EAA
382,000 acres
46% U.S.
Palm Beach, Glades, Hendry
Sugar
39. Phosphorus loading to S. Florida Ecosystem
Inputs North
and South of
Okeechobee
Dairy/Beef
Agriculture
Kissimmee Basin
40. Dairy and Beef Kissimmee drainage basin 12,000 km2
In 1521 Ponce de Leon
brought horses and cattle
to Florida, making it the
oldest cattle raising state
in the country.
No other part of our country
had cattle until the Pilgrims
brought cattle in the early 1600's
Florida's ranchers now raise
the third largest number of
cattle of any state east of the
Mississippi
(1947)
41. Phosphorus
Solid Manure:
5.5 g / kg total Phosphorus
One cow can excrete between 40
and 60 g of phosphorus per day
Subject to movement via runoff, stream
flow, soil water movement, and
groundwater movement
42. Cattle and Dairy
Okeechobee, Highlands, and Glades
Counties: 328,000 head (19% of total)
Okeechobee County is ranked number one for all cattle in the state
43. The Kissimmee river alone
contributes about 20% of the
phosphorus flowing into
Lake Okeechobee
The Lower Kissimmee River Basin is among
largest sources of external phosphorus loading to
Lake Okeechobee
Kissimmee – Okeechobee - Everglades
Okeechobee, in turn, is a source
of phosphorus to the Everglades
44. Surface Water Improvement Management Act: SWIM
SWIM Plan priority basins
Mandates phosphorus load level of 397 tons/yr
Clean Water act: 154.3 tons per year
deadline of January 1, 2015
Lake
(1987)
Target level of 40 ppb
in Lake Okeechobee
45. The Dairy Rule (1987)
creating lagoons to capture and contain dairy waste
Dairy Buy-Out Program
to facilitate removal of animals from dairies not able to comply
Works of the District Rule
permits are required for all discharges into waterways
Implement Best Management Practices (BMPs)
buffer areas around places animals congregate, eliminating
phosphorus fertilization near tributaries, reducing phosphorus
imports in animal feeds, reducing animal density
Some Strategies
19 of 45 Dairies Remain
46. SWIM target: 397 tons
Phosphorus Loads to Okeechobee
Above
Target
2007: 146 ton reduction of P entering Okeechobee
Above
SWIM
target
(tons)
47. Phosphorus concentrations in the Lake remain at about 117 ppb
The target level is 40 ppb.
2007: 146 ton reduction of P entering Okeechobee
48. Internal Loading
Decomposition of submerged aquatic vegetation
releasing phosphorus back into the water column
Dissolution of compounds in sediments which
bind and store phosphorus.
Two Sources
49. Phosphorus and Iron
Phosphorus has a strong affinity for iron
FePO4
Solid Precipitate
Readily incorporates into bottom sediments
Internal Loading
50. Internal Loading
Dissolved phosphorus combines with oxidized iron (Fe3+) to create
an insoluble compound that becomes buried in lake sediments.
If oxygen contents are reduced (anoxic bottom sediments) the
Fe3+ converts to Fe2+ which solubilizes the compound returning P to water.
P released by sediments is taken up by photosynthetic
algae faster than it can be returned to the sediments
Fe3+ + PO4
3- = Fe(PO4)
solid
(PO4)
Fe
to water
2+
Fe3+ high oxygen Fe2+ low oxygen
3-
Simplified:
51. RECOMMENDATION – Control Internal Phosphorus Loading.
Phosphorus-rich mud sediments need to be removed from the lake
to the maximum extent that is practical, in order to reduce internal
phosphorus loading. Unless this internal loading is substantially
reduced, it may take as long as 100 years for the lake to respond to
watershed phosphorus control programs.
Lake Okeechobee Action Plan
Developed by the Lake Okeechobee Issue Team
December 6, 1999
53. Hoover Dike (1932)
Everglades Agricultural Area (EAA)
Perimeter Levee (1954)
Water Conservation Areas
(management of flow)
Former extent of Kissimmee
Basin and floodplain
To Gulf
To Atlantic
56. Florida to Buy Out Sugar Land for Everglades
Restoration
WTVJ NBC 6
June 25, 2008: WEST PALM BEACH, Florida -- The largest U.S.
producer of cane sugar, U.S. Sugar Corp., would close up shop in a
$1.75 billion deal to sell its 292 square miles of land to Florida for
Everglades restoration, the company president and Florida Governor
Charlie Crist said Tuesday.
The deal, announced at a news conference at the Arthur R. Marshall
Loxahatchee National Wildlife Refuge, allows the state to buy U.S.
Sugar's holdings in the Everglades south of Lake Okeechobee, the
heart of the wetland ecosystem.
186,000 acres
58. Under flooded conditions, oxygen levels tend to be low
The diffusion of oxygen through water is about
1000 times slower than diffusion through air
Water restricts the movement of oxygen
Flooded Marsh
Organisms?
59. Aquatic Plants Die
Heterotrophic microorganisms decompose tissues
Aerobic heterotrophic organisms use oxygen
Oxygen becomes depleted in water; it cannot
diffuse fast enough to support aerobic heterotrophs
Anaerobic heterotrophs become dominant
60. Anaerobic Heterotrophic Organisms
Can use energy stored in complex carbon
compounds in the absence of free oxygen
The energy is obtained by exchanging
electrons with elements other than oxygen.
Nitrogen (nitrate)
Sulfur (sulfate)
Iron (Fe3+)
61. C6H12O6 + 3NO3
- + 3H2O = 6HCO3
- + 3NH4
+
1796 kJ
C6H12O6 + 3SO4
2- + 3H+ = 6HCO3
- + 3HS-
453 kJ
C6H12O6 + 6O2 → 6CO2 + 6H2O 2880 kJ
Anaerobic respiration is less efficient
and produces less energy.
Therefore, anaerobic decomposition is
much slower than aerobic decomposition.
62. Flooded Soils
additions
Losses (CO2)
Accumulation of organic
matter at the soil surface
Organic matter is added to the
soil faster than it can be
decomposed by microorganisms
Organic matter
limestone
anaerobic decomposition
of organic matter is
much slower than aerobic
decomposition.
63. Buildup of Organic soils
Organic matter decomposes slowly
when submerged in water.
(anaerobic decomposition)
Soils throughout the glades historically have
been submerged. (anaerobic conditions)
Led to vast amounts of organic matter
accumulation, sometimes >10 ft. thick.
Organic matter continues
to accumulate as long as
flooded conditions persist.
64. EAA
Drainage exposes soils
to oxygen and decomposition
by aerobic heterotrophic
organisms which can more
efficiently decompose
organic matter
Drainage
65. additions
Losses (CO2)
Aerobic decomposition
(much more efficient)
Conversion from anaerobic to
Drainage
Losses of organic matter
by decomposition exceed
new additions – soils disappear
C6H12O6 + 6O2 → 6CO2 + 6H2O
68. Public Funding Issues Revisited in State’s Buyout of U.S. Sugar
South Florida Business Journal - by Paul Brinkmann
a bill in the Florida Senate that would require voter approval
of any certificates of appreciation (bonds) issued by water districts.
69. Comprehensive Everglades Restoration Plan
restoration, preservation, and protection of the South Florida ecosystem
provide for water supply and flood protection
recover and sustain those essential hydrological and biological
characteristics that defined the original pre-drainage Everglades
Restoration of More Natural Flow Regimes
interconnected and interrelated wetlands
reestablishment of native plant communities
Low levels of nutrients