PhosphorousPhosphorous

Organic PhosphorousOrganic Phosphorous

Components of soil organic matter and plant tissue

Phosphate sugarsNucleic Acids (DNA/RNA)ATPPhospholipids

ATP

ImportanceImportance

Essential Macronutrient Limiting ResourcePresent in Fertilizers, animal wastes, wastewaterAvailability can be very limited

FertilityFertility

10 -15% of applied fertilizer phosphorous used by plants85 – 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)

P-impacted

Unimpacted

Soil PhosphorousSoil Phosphorous

PO4-3

Inorganic

H2PO4- HPO4

-2H3PO4

(Orthophosphate)

The form of available phosphorus is pH-dependent

Plant AvailablityPlant Availablity

H2PO4- HPO4

-2

pH 3-6 pH 8-11pH 6-8

Optimum pH = 6.5 for mineral soils

Most Available

Acidic Soils

Acid Soils (Low pH)Acid Soils (Low pH)

Aluminum and Iron availability increased at low pH

Al(OH)3FeOOH

Solubility increased

Al3+ Fe3+

Al(OH)3 + 3H+ = Al3+ + 3H2Oexample

Aluminum Precipitation at Low pHAluminum Precipitation at Low pH

H2PO4- (pH 3-6)

Al3+ + H2PO4- + 2H20 = Al(OH)2H2PO4 + 2H+

(Insoluble)

Al(PO4) • H2OVariscite

Al3+ + PO4-3 = Al(PO4)

simplified

Form of available P at low pH:

H2PO4- combines with free Al3+ and Fe3+

Basic Soils (High pH)

Calcium Binding in Basic SoilsCalcium Binding in Basic Soils

CaCO3

CaCO3 + 2H2(PO4)- = Ca [H2(PO4)]2 + CO32-

CaHPO4

Ca5(PO4)3OH (Apatite mineral)

(higher calcium availability)

H2(PO4)- is the available form of P

Availability and pHAvailability and pH

Low pH High pH

Aluminum and Iron phosphates

Calcium Phosphates

Formation of insoluble solids

Reaction with Soil MineralsReaction with Soil Minerals

Fixation on Iron and AluminumFixation on Iron and Aluminum

A dominant interaction between Phosphorus andsoils is strong interaction with Iron and Aluminum Oxides

Al

Al

OH

OH

OH

Fe

Fe

OH

OH

OH

Fixation: Aluminum/Iron oxidesFixation: Aluminum/Iron oxides

Fe

Fe

OH

OH

OH

H2(PO4)-+

Fe

FE

OH

OH

H2(PO4)-

OH-

+

Fe

Fe

OH

OH

OH

P OH

O-

OH

O-+

Fe

Fe

OH

OH

P OH

O-

OH

O-

Coatings on Sands and Silicate ClaysCoatings on Sands and Silicate Clays

Fe coating

Fe

Fe

OH

OH

H2(PO4)-

Organic Matter

Organic matter does not typically bind strongly with phosphorus.

Organic matter covers fixation sitesOrganic matter reacts with free Fe and Al

Organic matter competes for anion exch. sites

Organic Matter tends to increase P availability

-Plant Available

-Fe, Al bound -Calcium bound - Fixed on oxides

H2PO4- HPO4

-2

Al(PO4) • H2O

Ca3(PO4)2

H2PO4-

Inorganic Soil PhosphorousInorganic Soil PhosphorousInorganic

(low)

Phosphorus is generally removed from solution by soil processesThese processes have a finite capacity to retain phosphorusWhen the capacity is exceeded, phosphorus can become mobile.

South Florida and Phosphorus

Historic flow patterns in the Kissimmee – Okeechobee – Evergladessystem has been significantly altered, beginning in the late 1800’s.

The design was to drain significantareas for agriculture and developmentand to prevent floodwaters from communities to the south and east.

Historic Flow PatternsOkeechobee and the Everglades

Development

"The first and most abiding impression is the utter worthlessness to civilized man, in itspresent condition, of theentire region." Buckingham Smith

1835First Survey

In 1850, the Swamplands Act Passed

Population: 87,445

Transferred 20 million aces to FL for drainage and reclamation

11 miles (17.7 km) of canal south of Lake Okeechobee towardsMiami.

1881

Hamilton Disston

50,000 acres drained

Okeechobee north to Kissimmee and west to the Gulf of Mexico.

1904

“pestilence-ridden swamp”

Empire of the Everglades

Broward Elected

1905Everglades Drainage

District

Authorized Canals, taxes

By 1920, 4 major canal systems linked Okeechobee to the Atlantic,

By 1920

Began in 1881

Melaleuca Tree 1906

Invasive ornamental

359,000 acres

displaces native vegetation

6-12 ft. growth per year

19281911

1914-1918

Florida East Coast Railway

Tamiami Trail

WWI

Flagler

1928 Belle Glade Hurricane

135 mph winds

20-foot deep floodwatersSouth of Okeechobee

3000 to 8000 dead

143 miles of levee45 feet high and 150 feet wide

After the storm

Hoover Dike

19 water control structures

Hoover Dike (1932)

Everglades Agricultural Area (EAA)

Perimeter Levee (1954)

Water Conservation Areas(management of flow)

Former extent of KissimmeeBasin and floodplain

To Gulf

To Atlantic

Drainage

Historic Current

EAA

Phosphorus loading to S. Florida Ecosystem

Inputs Northand South ofOkeechobee

Dairy/Beef

Crop ProductionKissimmee Basin

Sugar, Rice, Veg.

700,000 ac

EAA

Crops: Everglades Agricultural Area

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 ofEverglades agriculture, and uses nearly 80% of the crop land in the EAA

Sugar and vegetable production contributes phosphorusto the ecosystem primarily through fertilizers and to a lesser extent throughdecomposition of plants.

EAA

382,000 acres 46% U.S.Palm Beach, Glades, Hendry

Sugar

Celery 260 200 140 80 20 0 0 0 0

Endive 200 175 150 125 100 75 50 25 0

Escarole 200 175 150 125 100 75 50 25 0

Lettuce (Head) 200 175 150 125 100 75 50 25 0

Radish 100 40 0 0 0 0 0 0 0

Romaine 200 175 150 125 100 75 50 25 0

Sugar Cane 120 100 80 40 20 0 0 0 0

Phosphorus Fertilization (lbs/ac)

Low Soil P V. High Soil P

Phosphorus loading to S. Florida Ecosystem

Inputs Northand South ofOkeechobee

Dairy/Beef

AgricultureKissimmee Basin

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)

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

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

The Kissimmee river alone contributes about 20% of the phosphorus flowing intoLake 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 sourceof phosphorus to the Everglades

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 ppbin Lake Okeechobee

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

SWIM target: 397 tons

Phosphorus Loads to Okeechobee

Above Target

2007: 146 ton reduction of P entering Okeechobee

Ab

ove

SW

IM ta

rge

t (to

ns)

Phosphorus concentrations in the Lake remain at about 117 ppb

The target level is 40 ppb.

2007: 146 ton reduction of P entering Okeechobee

Internal Loading

Decomposition of submerged aquatic vegetationreleasing phosphorus back into the water column

Dissolution of compounds in sediments whichbind and store phosphorus.

Two Sources

Phosphorus and Iron

Phosphorus has a strong affinity for iron

FePO4

Solid Precipitate

Readily incorporates into bottom sediments

Internal Loading

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) theFe3+ 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+ + PO43- = Fe(PO4)

solid

(PO4)Fe to water2+

Fe3+ high oxygen Fe2+ low oxygen

3-

Simplified:

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 PlanDeveloped by the Lake Okeechobee Issue Team

December 6, 1999

Lost Lands

Hoover Dike (1932)

Everglades Agricultural Area (EAA)

Perimeter Levee (1954)

Water Conservation Areas(management of flow)

Former extent of KissimmeeBasin and floodplain

To Gulf

To Atlantic

Historic Current

EAA

Sugar, Rice, Veg.

700,000 ac

EAA

Crops: Everglades Agricultural Area

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

Organic soils possessinghigh natural fertility

Historically flooded

Under flooded conditions, oxygen levels tend to be low

The diffusion of oxygen through water is about1000 times slower than diffusion through air

Water restricts the movement of oxygen

Flooded Marsh

Organisms?

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

Anaerobic Heterotrophic Organisms

Can use energy stored in complex carbon compounds in the absence of free oxygen

The energy is obtained by exchangingelectrons with elements other than oxygen.

Nitrogen (nitrate)Sulfur (sulfate)

Iron (Fe3+)

C6H12O6 + 3NO3- + 3H2O = 6HCO3

- + 3NH4+ 1796 kJ

C6H12O6 + 3SO42- + 3H+ = 6HCO3

- + 3HS- 453 kJ

C6H12O6 + 6O2 → 6CO2 + 6H2O 2880 kJ

Anaerobic respiration is less efficientand produces less energy.

Therefore, anaerobic decomposition is much slower than aerobic decomposition.

Flooded Soilsadditions

Losses (CO2)

Accumulation of organic matter at the soil surface

Organic matter is added to thesoil faster than it can be decomposed by microorganisms

Organic matter

limestone

anaerobic decomposition of organic matter is much slower than aerobic decomposition.

Buildup of Organic soils

Organic matter decomposes slowly when submerged in water. (anaerobic decomposition)

Soils throughout the glades historically havebeen submerged. (anaerobic conditions)

Led to vast amounts of organic matteraccumulation, sometimes >10 ft. thick.

Organic matter continuesto accumulate as long asflooded conditions persist.

EAADrainage exposes soilsto oxygen and decompositionby aerobic heterotrophicorganisms which can moreefficiently decomposeorganic matter

Drainage

additions

Losses (CO2)

Aerobic decomposition (much more efficient)

Conversion from anaerobic to

Drainage

Losses of organic matterby decomposition exceed new additions – soils disappear

C6H12O6 + 6O2 → 6CO2 + 6H2O

Subsidence of Organic soils

up to 10 feet

1912 to 2000

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.

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

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