Presentation on theme: "Effects of Conservation Tillage Systems on Dissolved Phosphorus Dr. David Baker Heidelberg University Tiffin, Ohio 44883 November 15, 2012 Davenport, IA."— Presentation transcript:
Effects of Conservation Tillage Systems on Dissolved Phosphorus Dr. David Baker Heidelberg University Tiffin, Ohio 44883 November 15, 2012 Davenport, IA Building Science Assessments for State-Level Nutrient Reduction Stategies
This talk -- Lessons learned from agricultural phosphorus control programs in the Lake Erie Basin The teacher has been: 1.Detailed, long-term monitoring data for several major watersheds draining into Lake Erie. 2.Information on changing crop production practices in those watersheds. This research was supported by state and federal agencies, foundations, agribusinesses and the fertilizer industry. Special thanks to the EPA’s Great Lakes National Program Office and the Great Lakes Protection Fund for recent support for bioavailability studies and phosphorus stratification studies.
15 stations All at USGS Stream Gages Today’s data from three rivers: Maumee – 6,330 sq.mile Sandusky – 1,250 sq. mile Cuyahoga - 708 sq. mile
1.Suspended solids 2.Total phosphorus 3.Dissolved reactive phosphorus 4.Nitrate 5.Nitrite 6.Ammonia 7.Total Kjeldahl Nitrogen 8.Chloride 9.Sulfate 10.Silica 11.Fluoride 12.Conductivity Seasonally pesticides Selected metals Bioavailable Phosphorus Analytical Program at the NCWQR Program started in 1975 ~ 500 samples analyzed per station per year Annual loads calculated by integration with corrections for final USGS daily discharge Data available at Heidelberg’s web site: http://www.heidelberg.edu /academiclife/distinctive/nc wqr/data Program Characteristics:
Total Phosphorus Load Total Particulate Phosphorus Load Total Dissolved Phosphorus Load += Total Bioavailable Phosphorus Load += Bioavailable Particulate Phosphorus Load Bioavailable Dissolved Phosphorus Load Management Options for Phosphorus Load Reduction Focus of reduction programs
Nonpoint phosphorus control programs were planned in the 1980s and initiated in the 1990s. Particulate Phosphorus 82% Dissolved Phosphorus 18% Forms of phosphorus transported in northwestern Ohio rivers, 1975-1987. Phosphorus reduction programs focused on reducing erosion and particulate phosphorus loading through fostering adoption of no-till and reduced till crop protection methods. Particulate phosphorus during storm runoff is attached to soil particles.
1. What does the water quality monitoring data look like? 2. What changes in agricultural practices could explain the loading changes? 3.What changes in hydrology could help explain the loading changes?
Trends in annual loads and flow weighted mean concentrations of particulate phosphorus in the Maumee and Sandusky rivers
Note the close relationship between variations in annual discharge and variations in TP load. Discharge increased by 41% while TP load increased by 31%. Weather and hydrology drive nonpoint pollution from cropland.
Trends in annual loads and flow weighted mean concentrations of dissolved reactive phosphorus in the Maumee and Sandusky rivers
Dissolved Reactive Phosphorus 50% decrease from 1982-2011 Total Phosphorus 24% decrease from 1982-2011
From here To here With some very good years in between!
Phosphorus reduction programs in the Lake Erie Basin have been driven by the lake’s eutrophication problems. Point source control problems were initiated first and quickly resulted in substantial reductions in phosphorus loading.
Maumee and Sandusky 26% of land area 51% of total phos. load Export rate 3x higher than average for rest of drainage area How does nutrient export from the Northwestern Ohio rivers compare with the export from other areas?
Land use in study watersheds, as percent Watershed Agricul -ture Forest Grass_ Hay_ Pasture Open Water UrbanWetlandOther Maumee184.108.40.206.710.62.30.2 Sandusky220.127.116.11.58.10.3 Cuyahoga9.033.611.82.618.104.22.168 Average annual nutrient export rates, 1996-2011
Data for 2004-2008 Water Years Watershed Point source Phosphorus Non-Point Phosphorus Maumee5%95% Sandusky3%97%
Trends in tillage practices in northwestern Ohio: 1989-2004
Phosphorus fertilizer sales in Ohio, 1955-2007 Heidelberg Monitoring started
Start of Heidelberg monitoring Long-term trend in average phosphorus soil tests in Northwest Ohio
Fertilizer application method # of fields % of fields 1Broadcast and unincorporated21120% 2Broadcast and incorporated within one week 21221% 3Broadcast and incorporated after one week or more 11511% 4Banded with corn planter49646% 5Banded more than 2 inches deep with a coulter/knife injection tool 232% Total number of reported fields 1,030 100% How will the majority of phosphorus fertilizer be applied to this field? Sandusky Watershed Soil Stratification Studies
Timing of fertilizer application# of fields % of fields 1In spring (April to June), prior to planting 868.4 % 2In spring (April to June), at planting51350.0 % 3 In late summer or fall (August – November) after wheat or hay harvest. 929.0 % 4 In fall (September – November) after soybean harvest 28327.6 % 5 In fall, (September – November) after corn harvest 474.6 % 6 In winter (December – March) 40.4% 7 In winter (December – March) on snow covered or frozen soils. 10.1 % Total Responses1,026 When will the majority of phosphorus fertilizer be applied?
Total Phosphorus Loading Total Bioavailable Phosphorus Loading
A bottom line … 1.After 20+ years of efforts to reduce phosphorus loading to Lake Erie from cropland, we now have more bioavailable phosphorus entering Lake Erie from cropland than ever. 2. The increases in bioavailable phosphorus loading are due to increases in dissolved phosphorus runoff. 3. The increases in dissolved phosphorus loading appear to be contributing increased harmful algal blooms in Lake Erie.
Characteristics of average annual export of phosphorus from the Sandusky River, 2002-2011 Total Phosphorus (594 metric tons/year) 73% particulate phosphorus 27% dissolved phosphorus Bioavailable Phosphorus (275 metric tons/year) 46% particulate phosphorus 54% dissolved phosphorus Management choice impacts-- Trading TMDLs BMP selection 93% bioavailable 29% bioavailable
Why has the dissolved phosphorus loading from the Sandusky and Maumee rivers dropped and then increased so much? Potential causes of the increasing dissolved phosphorus export 1.increasing fall and winter broadcasting of phosphorus fertilizers, often without timely incorporation. 5. changes in rainfall patterns that have resulted in increases in winter rainstorms and resulting stream flows, especially in December and January. 2.phosphorus stratification in the soil associated with widespread adoption of no-till and reduced-till production and the accompanying lack of inversion tillage. 3.increased tile drainage coupled with macropore flow that carries surface water to tile drains and increases total discharge. 4.increasing trends in flashiness of northwestern Ohio streams.
Phosphorus stratification in cropland of the Sandusky Watershed
NCWQR Phosphorus Analyses Sample Pretreatment Portion Analyzed acid added oxidant added auto- clave Dissolved Phosphorus (DP) (filter sample through 0.45 micron filter) Total Phosphorus (TP)whole sample xxx NaOH Extractable PP (extract residue on filter with NaOH and analyze as DRP) Particulate Phosphorus (PP)calculated as TP - TDP Dissolved Organic P (DOP)calculated as TDP - DHP Total Dissolved P (TDP) x xx filtrate Dissolved Hydrolyzable P (DHP) xx filtrate --- Dissolved Reactive P (DRP)filtrate --- all samples extra analyses for bioavailability studies Bioavailable Forms