Topics. What was wrong with Lake Erie?

Transcription

1 Nutrient management, conservation tillage, adaptive management, and increased dissolved phosphorus export from Northwest Ohio agricultural landscapes R. Peter Richards, David B. Baker, Jack W. Kramer, and John P. Crumrine National Center for Water Quality Research Heidelberg College Tiffin, Ohio Topics Managing eutrophication Phosphorus forms Phosphorus trends Possible causes Research/management needs/next steps Austin, TX 15th EPA National NPS Monitoring Program Workshop August 3, 27 June 22, 1969 What was wrong with What was wrong with Lampreys Alewives Cladophora Overfishing Blue Pike Walleye The Dead Lake Anoxia Contaminated Harbors Oil and grease Phenols Iron and other metals PAHs PCBs Contaminated Open Lake and Fish Mercury PCBs No more mayflies... DDT, DDE Manage phosphorus as limiting nutrient Reduce both point and non-point sources STPs > 1 mgd limited to 1 mg/l effluent, later urged to.5 mg/l Phosphorus banned from laundry detergent Erosion control - conservation tillage, buffer strips, etc Improved fertilizer and manure management Target load: 11, metric ton/year from all sources First met in, frequently after Lake showing good improvement; zebra mussels ~ Renewed problems starting late 199s Worsened hypoxia Blooms of Cladophora and cyanobacteria Causes: Restructured ecosystems Increased tributary loads 1

2 Phosphorus concentrations have increased. Zebra mussels, tributary loads, or both Western Basin Central Basin Cladophora and noxious bluegreen algae are back with a vengence! Where are the nutrients that drive this coming from David Rockwell, U.S. EPA GLNPO Tom Bridgeman, U. Toledo Background: NCWQR Monitoring Raisin II. Phosphorus Forms Ontario Grand Indiana Michigan Ohio Lake Erie Pennsylvania New York Maumee Sandusky Cuyahoga Reactive Kilometers W N E Particulate Reactive Particulate =TP-DRP Autosamplers at USGS stations, 3 samples per day Sediment, nutrients, major ions 1974 to present S (Particulate) ( Non-reactive) III. Phosphorus trends Many ways to study trends ANCOVA on log-transformed concentrations adjusted for flow using LOWESS, with back-transformation and bias correction Tis a gift to be simple Annual loads and annual flow-weighted mean concentrations; FWMC = load/discharge III. Phosphorus trends - TP Loads TP Load, metric tons 4, 3, 3, 2, 2, 1, 1, Maumee River Loads, tonnes/yr -86 tonnes/por -34% for POR p=.65 n.s

3 III. Phosphorus trends - DRP Loads III. Phosphorus trends - TP FWMCs DRP Load, metric tons Maumee River Reactive Phosphorus Loads, tonnes/yr -37 tonnes/por -1% for POR p=.724 n.s., mg/l FWMCs, mg/l/yr mg/l/por -42% for POR p= III. Phosphorus trends - PP FWMCs III. (Sediment trends - SS FWMCs) Particulate Phosphorus FWMCs, -26 Suspended Soilds FWMCs, -26 Particulate Phosphorus, mg/l mg/l/yr mg/l/por -45% for POR p=.4 Suspended Soilds, mg/l mg/l/yr -131 mg/l/por -48% for POR p= III. Phosphorus trends - DRP FWMCs III. Phosphorus trends - DRP/TP Reactive Phosphorus, mg/l Reactive Phosphorus FWMCs, (1992).2 Parabolic trend -57% decrease 94% increase net -16% for POR p(yr 2 )<.1 DRP/TP, % 3.% 25.% 2.% 15.% 1.% 5.% Reactive Phosphorus as percent of, % 12.1% () 27.2% Parabolic trend -57% decrease 125% increase net +27% for POR p(yr 2 )= %

4 III. Phosphorus trends - summary SS, TP and PP : substantial and sustained decreases over the period of record DRP and %DRP: major decreases to about 199 followed by major increases Change point about the same as that in lake itself IV. Causes: Point Source Increases Reported 45 point source loads Phosphorus Load Municipal and Industrial Point Source Loads (metric tons/year Muni Load 4 Indus Load Not much change since 199 Only ~11% of total Maumee load, 15-25% of total load to IV. Causes: Point Source Increases Numbers of septic systems Rural Septic System Permits Since, Sandusky River Coun Farm animals Number of Cattle 35, Cumulative Number of Permits , 25, 2, 15, 1, 5, 12,, 1,, 8,, 6,, 4,, 7, 6, 5, 4, Number of Chickens Number of Milk Cows 11 of 22 Counties censored 1 of 22 Counties censored Note: Data for Sandusky watershed, since only 3, ,, , , Soil fertility Phosphorus Soil Test trend, NW Ohio Nutrient stratification with conservation tillage P profiles for three farms with 2 years no-till: Glenford silt loam Hoytville silty clay loam Blount silt loam, two fields 12 1" 1" 2" 2" -1.5" Bray P1 lb/acre OSU A&L CN-SB Crop Need Level 3" 4" 5" 6" 7" 8" 9" 1" 3" 4" 5" 6" 7" 8" 9" 1" " " " Crop Needs Average over top 8 inches " 12" " 12" " Soil Test P, lb/acre Soil Test P, lbs/acre Soil Test P, lbs/acre 4

5 IV. Other possible causes/ contributing factors Increased fall fertilization with cover crops Increased spreading of manure on cover crops in fall and winter Decreasing soil organic carbon => decreased ability to hold P in the soil 22% decrease -26 V. Needs/next steps More and better data non-traditional point sources Soil fertility and its vertical distribution Continued/expanded windshield surveys of crops/tillage Better Ag Census-type data; higher resolution E.g. Zip code rather than county level Easing of censoring of data Integrative models that tie landscape sources together and link them to the Lake and its ecosystems BMPs to address soil eutrophication and stratification Adaptive Management!!!! V. Signs of progress Protection Fund grant to start soil fertility testing Great Lakes Protection Fund grant (we hope) to build soil fertility data; develop, implement and evaluate BMPs Partnerships with farmers, ag extension, Certified Crop Advisors Joyce Foundation investments in watershed work Sandusky River a Targeted Watershed Western Basin Partnership Ohio Phosphorus Taskforce Conclusions is in eutrophication trouble again. Total and particulate phosphorus concentrations and loads in the tribs are decreasing. But dissolved phosphorus concentrations and loads are increasing over the last decade. Unnecessary soil fertility and increased stratification may be playing a major role. Adaptive management responses are needed. Now! Detailed tributary monitoring data saved valuable time in assessing causes and designing responses. What s the cost of ignorance! The End Rock Creek 6/25/6 5