Toledo, OH Loadings from Landscapes Workshop March 18, 2008 Trends in Dissolved Reactive Phosphorus in Lake Erie Tributaries R. Peter Richards, David B. Baker, John P. Crumrine National Center for Water Quality Research Heidelberg College Tiffin, Ohio 44883
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Toledo, OH Loadings from Landscapes Workshop March 18, 2008
Trends in Dissolved Reactive Phosphorus in Lake Erie Tributaries
R. Peter Richards, David B. Baker, John P. CrumrineNational Center for Water Quality Research
Heidelberg CollegeTiffin, Ohio 44883
Maumee
Vermilion
Sandusky
Raisin
N
EW
S
0 40 80 Kilometers120
Lake Erie
Grand
Cuyahoga
Background: NCWQR Monitoring
Autosamplers at USGS stations, 3 samples per daySediment, nutrients, major ions1974 to present, ~15,000 samples per station
Michigan
PennsylvaniaOhio
New York
Ontario
Indiana
LakeErie
Trends are subtle things!
Dai
ly d
isch
arge
, Mau
mee
Riv
er
Trends in concentrations of:Suspended Solids Particulate Phosphorus
Lake Erie: re-emerging issues
Cladophora and noxious “blue- green algae” are back with a vengence!
Where are the nutrients that drive this coming from?
Tom Bridgeman, U. Toledo
Lingbya
Lake Erie issues
Cladophora
Trends in dissolved reactive PDaily average concentration DRP as % of total P
Summary of trendsPercent change per decadein average concentrations
* For DRP, percent decrease per decade prior to 1995 followed by percent increase since then.
Maumee Sandusky
Flow 4.6 4.9
SS -18 -11
PP -14 -10
DRP* -58, 151 -64, 273
Dissolved Reactive Phosphorus load
0
50
100
150
200
250
300
0 31 61 92 122 153 183 214 244 275 305 336 366
Day of Water Year
DRP loads in 2007 (Sandusky)
Highest in 33 years of monitoring>3x average, recurrence interval >1000 yrsA consequence of warm fall weather interacting with farming practices, reinforcing the general trend of increasing loads over the last decade
Sources and transportSuspended solids, particulate phosphorus, and dissolved reactive phosphorus are transported to the tributary system primarily by surface runoff following storms.The major source of increased DRP must be rural non-point. Point sources are responsible for only a small fraction (<10%) of the P loading in these watersheds.Land use is 80% row crop agriculture -corn/soy/wheat
But… an asideUpward trends in DRP also seen in Cuyahoga and Grand watershedsThese are more urban/forested watershedsConcentrations are highest under low flowPoint sources or “pseudo point sources”, e.g. septic systemsThese tribs have a smaller impact on Lake Erie than Maumee and Sandusky
Possible causes for increased DRP: urban
Aging wastewater treatment infrastructureMore and/or failing septic systemsAdditions of DRP to drinking waterIncreased use of dishwashers with P-containing detergentUrban lawn careWe believe these are minor contributors to the overall problems affecting Lake Erie
Possible causes for increased DRP: rural
http://www.ars.usda.gov/is/np/Phos&Eutro2/agphoseutro2ed.pdf
Increased soil P levels
Possible causes for increased DRP: rural
Increased soil P levelsLong term phosphorus soil test trends for NW Ohio
0
20
40
60
80
100
120
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
lbs/
ac B
ray
P1 OSU Lab
Logan
OSU LabCalhoun
A&LLab
Wheat,alfalfa
Corn, soy
Possible causes for increased DRP: rural
Concentration of soil P near surface where it can interact with rainfall and dissolvePhosphorus Stratification After 20 Years of No-till on a
Blount silt loam, Seneca County, OH
-7-6-5-4-3-2-10
0 20 40 60 80 100
lbs/ac Bray P1
Dept
h Be
low
Soi
l Su
rface
- In
ches
South Part FieldNorth Part Field
Standard 8 inch soil test:South Field 48 lbs/acNorth Field 54 lbs/acBill McKibben, CCALogan Labs
Mean Annual TP in Runoff as a Function of Tillage Management
0.001.002.003.004.005.006.007.00
1980
1982
1984
1986
1988
1990
1992
1994
Tota
l P (m
g/L)
Conv.No-till
Reducingtillage can decrease TPin runoff …
Mean Annual DP in Runoff as a Function of Tillage Management
0.00
0.20
0.40
0.60
0.80
1.00
1980
1982
1984
1986
1988
1990
1992
1994
Diss
olve
d P
(mg/
L)
Conv.No-till
…but it canincrease DPin runoff.
Sims and Kleinman.2006. Phosphorus
Paired treatment begins
Possible causes for increased DRP: rural
Interviews with fertilizer dealers: how do your customers apply P and K?
Fall applicationOn the surface without incorporationBefore corn for both corn and soybean needsThis is necessary or convenient because of increased conservation tillage
Fall and winter application of manure also a concern, especially on frozen ground
Where are we headed?Causes for concern:
Ethanol means more corn, the heaviest user of fertilizerHigh crop prices mean conversion of CRP to crops, especially cornMore CAFOs
Causes for hope:Fertilizer and fuel costs up, creating incentives to be efficientMany fields already have more than optimal P levels. A teachable situation?
Possible approaches to solutionsMore extensive soil testingStratified soil testingP Index as fertility guideSpring fertilizationIncorporation of manure and chemical fertilizerOccasional inversion of the soil
The Bottom Line….Value of nutrients that went down the Maumee River in WY2007, based on 2008 fertilizer prices:
Phosphorus: $9,100,000Nitrogen: $57,500,000Total: $66,600,000$16.43/acre
Overall ConclusionsSuspended solids and particulate phosphorus loads have declined over the last 30 years, mostly as a consequence of conservation tillageDissolved reactive phosphorus declined sharply initially, but has increased equally sharply in the last 10 yearsBecause DRP is highly bioavailable, these increases are a cause for concern for the ecological health of Lake ErieBMP toolbox may need modification to deal with dissolved P rather than total P
Key QuestionsWhat do we look for that indicates the connection between land-use and transported materials?
Temporal patterns of concentration in relation to storm runoffWhat are key variables of concern? (stressor variables; response variables)
SS, TP, DRP; algae, DO, hypoxiaWhich variables could be used as land-based state indicators?
% agricultural land use, TP content of soils, tillage practicesWhat would you say are acceptable ranges of these variables?
Soil P: <2x level for optimal crop production, <80 lb/acre Bray 1 PWhat databases are available? Measurement technology?
WQ: NCWQR. Land: NASS. Tech: precision nutrient managementWhat are the research needs/land-based measurements?
Soil fertility, stratification. Uncensored animal numbers. Linked models.What is the role of watershed loading models in synthesizing information and data and in predicting the watershed response to source control actions?
Important potential, not yet realized. Critical for exploring alternative scenarios. The only way to sort out zebra mussels vs. tributary loading? See EcoFore 2006 project.
The End
Rock Creek 6/25/06
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