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Data on Nitrate in Groundwater and Factors that …...2020/02/27  · Practice Details % Nitrate-N...

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  • Kevin Masarik

    NR151 Technical Advisory Committee

    February 27, 2020

    Data on Nitrate in Groundwater and

    Factors that Determine Nitrate

    Groundwater Quality

  • Our nitrate challenge:The top foot• Current agricultural systems allow for significant

    nitrate losses to groundwater – much of it can occur outside the growing season

    • Soils and geologic considerations can exacerbate losses from agricultural systems

    • Future management priorities/challenges:• 1) Encourage but also need to better quantify nitrate

    reduction from different management strategies• Cover crops• Diversification of crop rotations• Etc.

    • 2) Climate change will impact nitrate losses to groundwater

    • More extreme rainfall events• Longer growing season• Increased soil temperature

    • 3) Be more intentional about residential development with private wells in rural areas/subdivisions

    • Proximity to agricultural areas• Density of septic systems

  • Groundwater 101

    Source:

    Merritts, Menking, & De Wet, Environmental Geology: An Earth Systems Science Approach. 2nd Edition. 2014

  • Modified from: https://nevegetable.org

    Groundwater

    Sources of Nitrogen to

    Agricultural Fields

    NO3-

    Fertilizers

    Nitrate in irrigation water

    NO3-

    Nitrogen Cycle

    N2O

    N2

    Runoff, Wind Erosion

    https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjr95zfs8jJAhWFhoMKHevgC2cQjRwIBw&url=https://nevegetable.org/cultural-practices/nitrogen&bvm=bv.108538919,d.amc&psig=AFQjCNE_sxqv8I8AWxw1MKcz-wWdjbPpkA&ust=1449531480589067https://nevegetable.org/

  • Nitrate and Human HealthInfants and pregnant women• Methemoglobinemia or “blue-baby syndrome”• Central nervous system malformations (birth defects & miscarriages)

    AdultsPossible correlations to:• Non-Hodgkin’s lymphoma• Various cancers (ex. gastric, bladder)• Thyroid function• Diabetes in children

    Nitrate often indicator of other possible contaminants (ex. other agricultural contaminants, septic effluent, etc.)

    Wisconsin Groundwater Coordinating Council, 2015; Weyer, 1999

    http://dnr.wi.gov/topic/groundwater/documents/GCC/GwQuality/Nitrate.PDFhttps://www.leopold.iastate.edu/news/leopold-letter/1999/fall/should-we-worry-about-nitrate-our-water

  • Nitrate Nitrogen• Greater than 10 mg/L

    Impacted at a level that exceeds state and federal limits for drinking water

    • Greater than 1 mg/L Evidence of land-use impacts

    • Less than 1 mg/L Natural or background levels in WI groundwater

    0

    10

    1

    • DO NOT give water to infants

    • DO NOT consume if you are a woman who is pregnant or trying to conceive

    • RECOMMEND everyone avoid long-term consumption

    Nitrate-Nitrogen Concentrations

    Considered suitable for drinking water

  • Nitrate exported to surface waters

    http://water.usgs.gov/nawqa/sparrow/gulf_findings/delivery.html

    • Excessive nutrients contribute to growth of large amounts of algae that decay and consume oxygen –hypoxia.

    • Some algal blooms can be harmful to health

    Algae bloom on Wisconsin’s Lake Tainter. (photo: Peg McAloon)

    http://water.usgs.gov/nawqa/sparrow/gulf_findings/delivery.html

  • Decades

    Mu

    nic

    ipal

    Wel

    l

    Pri

    vate

    Wel

    l

  • Private Well Nitrate Concentrations

  • WI Well Water Viewer, 2019

    Average Nitrate-Nitrogen Concentration by Township

  • Nitrate-N breakdown

    • 57% of private wells have concentrations less than 2 mg/L

    • >40 mg/L: 0.12%*; 960 wells1

    • >30 mg/L: 0.56%*; 4,480 wells1

    • >25 mg/L: 1.0%*; 8,000 wells1

    • >20 mg/L: 2.2%*; 17,600 wells1

    • >10 mg/L: 8.2%**; 10%*, 65,600-80,000 wells1

    *estimate from Center for Watershed Science and Education database, UW-Extension/UW-Stevens Point

    **estimate from Agricultural Chemicals in Wisconsin Groundwater, DATCP. 2017

    Based on estimate of 800,000 private wells, GCC Report to the Legislature, https://dnr.wi.gov/topic/groundwater/GCC/wells.html

    Pro

    po

    rtio

    n o

    f w

    ells

    Nitrate Concentration (mg/L)

    10

    Greater than 10 mg/L drinking water standard

    https://dnr.wi.gov/topic/groundwater/GCC/wells.html

  • Agricultural Lands of WisconsinAnnual Row Crops

    Forage Crops/Pasture/CRP

    Maps produced using WISCLAND Data Coverage. 2002. WiDNR/EDM

    ~20% of samples exceed the 10 mg/L nitrate-nitrogen standard when more than 75% of the area is cultivated (DATCP, 2017)

  • Coarse textured surficial deposits

    Map created using: Groundwater Contamination Susceptibility Model (GCSM); Surficial Deposits ("sdppw95c")

    The GCSM was developed by the DNR, the US Geological Survey (USGS), the Wisconsin Geological & Natural History Survey (WGNHS), and the University of Wisconsin – Madison in the mid-1980s.

  • Shallow carbonate rock aquifers

    Photo credits: Ken Bradbury, WGNHS

  • Wisconsin Karst Potential

  • Nitrate Variability in Wisconsin’s Groundwater

  • Less

    Nitrogen Fertilizer Added (lb/acre)

    More

    N-P-K

  • Yie

    ld o

    r B

    iom

    ass

    Acc

    um

    ula

    tio

    n (

    kg/h

    a)

    Fertilizer Added (kg/ha)

    Increasing

    Yield response to nitrogen

    Incr

    easi

    ng

    Maximum Yield

    0

    Slope = Added Yield

    Fertilizer UnitEconomic Optimum / MRTN• variable from year to year depending on energy costs, fertilizer costs, price of commodities, temperature, precipitation, etc.

  • Yie

    ld o

    r B

    iom

    ass A

    ccu

    mu

    lati

    on

    Fertilizer Added

    Increasing

    Incre

    asin

    g

    100%

    0

    Yield Optimum

    Economic Optimum / MRTN

    • variable from year to year

    depending on energy costs,

    fertilizer costs, price of commodities

    Nitrogen Recommendations

    Environmental Optimum

    • depends on climate, soils, geology, etc.

    • What is our goal…MCL, PAL, zero?

    • depends on who you are…infant, parent, farmer, etc.

  • Alternative Field Crops Manual, 1989. University of Minnesota and University of Wisconsin -MadisonNutrient application guidelines for field, vegetable and fruit crops in Wisconsin. A2809. 2012. University of Wisconsin-Madison

    Miscanthus and switchgrass recommendations: Anderson et al., 2013; McIsaac et al., 2010; Vogel et al., 2002; Arundale et al, 2014

    Nitrogen fertilizer recommendations for common crops

    * Legumes have symbiotic relationship with N fixing bacteria

    http://learningstore.uwex.edu/assets/pdfs/A2809.pdf

  • Estimating Nitrogen Leaching Potential

    From Meisinger, J.J and Randall G.W. 1991. Chapter 5: Estimating Nitrogen Budgets for Soil-Crop Systems. In Managing Nitrogen for Groundwater Quality and Farm Profitability, editors: Follett, Keeney, and Cruse. Soil Science Society of America.

    Potential N Leaching = N Inputs - N Outputs (excluding leaching) - Change in N Stored

    Runoff, Wind Erosion

  • Measuring nitrate leaching below an irrigated field in the Central Sands Region

    2016 2017 2018 2019

    X 4Installed 2016

    40 ft

    ~2-3 weeks

  • Drainage Volume X Concentration = Nitrate Leaching

    X =

  • Flow Weighted

    Mean (FWM)

    Cumulative Nitrate Leaching Loss ÷ Annual Drainage = Flow-weighted Mean Nitrate Concentration

  • Nitrogen Leaching Losses

  • Nitrogen Leaching Losses

  • Estimating Leaching Losses Using a Nitrogen Budget

  • Nitrogen Leaching Losses

  • Accounting for spatial variability at the field scale using wells

  • Accounting for spatial variability at the field scale using wells

  • Nitrate Leaching at Arlington, WI

  • Nitrate Leaching at Arlington, WI

  • Nitrate Leaching at Arlington, WI

  • N

    Or

    Water (inches) x Nitrate-Nitrogen Concentration (mg/L) x 0.226 = Pounds of Nitrogen per Acre(8 in.) x (10 mg/L) x 0.226 = 18.1 lbs N/acre

    1 2 3 4 5 10 15 20 30 40

    Inches of

    Irrigation

    1 0.2 0.5 0.7 0.9 1.1 2.3 3.4 4.5 6.8 9.0

    2 0.5 0.9 1.4 1.8 2.3 4.5 6.8 9.0 13.6 18.1

    3 0.7 1.4 2.0 2.7 3.4 6.8 10.2 13.6 20.4 27.1

    4 0.9 1.8 2.7 3.6 4.5 9.0 13.6 18.1 27.1 36.2

    5 1.1 2.3 3.4 4.5 5.7 11.3 17.0 22.6 33.9 45.2

    6 1.4 2.7 4.1 5.4 6.8 13.6 20.4 27.1 40.7 54.3

    7 1.6 3.2 4.7 6.3 7.9 15.8 23.7 31.7 47.5 63.3

    8 1.8 3.6 5.4 7.2 9.0 18.1 27.1 36.2 54.3 72.4

    9 2.0 4.1 6.1 8.1 10.2 20.4 30.5 40.7 61.1 81.4

    10 2.3 4.5 6.8 9.0 11.3 22.6 33.9 45.2 67.8 90.5

    Nitrate-Nitrogen Concentration (mg/L)

    lbs of Nitrogen per acre

    Estimating nitrogen from irrigation or leaching losses using concentration

    Water in inches

  • 365

    Graph of root depth: http://www.bae.ncsu.edu/programs/extension/evans/ag452-1.html

    Picture of corn roots: http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch2.html

    http://www.bae.ncsu.edu/programs/extension/evans/ag452-1.htmlhttp://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch2.html

  • Comparing an Annual Row Crop to Perennial Ecosystems

    http://soils.usda.gov/sqi/management/files/RSQIS6.pdf

    Mixed Native Perennial

    http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch2.html

    Nitrogen fertilizer use efficiency for Midwestern corn systems

    37%(Cassman et. al. 2002)

    http://www.bae.ncsu.edu/programs/extension/evans/ag452-1.html

    http://soils.usda.gov/sqi/management/files/RSQIS6.pdfhttp://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch2.htmlhttp://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1356&context=agronomyfacpubhttp://www.bae.ncsu.edu/programs/extension/evans/ag452-1.html

  • Effect of cropping systems on nitrate leaching loss in the Midwest

    Cropping

    systemsN Inputs

    Nitrate-N

    Leaching

    Water

    DrainageData Source

    kg N ha-1 yr-1 kg N ha-1 yr-1 mm yr-1

    Annual

    Corn-Corn 138 55 193 Randall et al., 1997 (1)

    180 37 399 Masarik et al., 2014 (2)

    151-221 17-32 63-187 Thomas et al., 2014 (3)

    202 63 590 Weed and Kanwar, 1996 (4)

    202 43 280 Randall and Iragavarapu, 1995 (5)

    Corn-Soybean 136-0 51 226 Randall et al., 1997 (1)

    168-0 34-46 ND McIsaac et al., 2010 (6)

    168-0 34 470 Weed and Kanwar, 1996 (4)

    171-0 10-35 ND Cambardella et al., 2015 (7)

    Mixed C-S-O/A-A 171-0-57-0 8-18 ND Cambardella et al., 2015 (7)

    Perennial

    Alfalfa 0 2 104 Randall et al., 1997 (1)

    CRP 0 1 160 Randall et al., 1997 (1)

    Switchgrass 0

  • Nit

    rate

    Le

    ach

    ing

    Po

    ten

    tial

    Forest/Prairie/CRP

    0

    Alfalfa Soybean Corn Potato

    Corn-Soybean

    Economic Optimal Nitrogen Rates

    Water Quality/ Nitrate Concentration

    Less Greater

    Masarik, UW-Extension

    Nitrate Leaching Potential

  • Long-term nitrogen reduction strategies for agricultural areas

    Practice Details % Nitrate-NReduction (StDev)

    Reduction potential

    Uncertainty

    Timing

    Fall to Spring Pre-plant 6 (25) Low High

    Spring pre-plant/sidedress 40-60 split compared to fall applied

    5 (28) Low High

    Sidedress – Soil test based compared to pre-plant 7 (37) Low High

    Nitrification InhibitorNitrapyrin – Fall – Compared to applied w/out nitrapyrin

    9 (19) Low Medium

    Cover CropsRye 31 (29) Medium Medium

    Oat 28 (2) Medium Medium

    PerennialBiofuel Crops (ex. switchgrass, miscanthus) 72 (23) High Medium

    Conservation Reserve Program 85 (9) High Low

    Extended RotationsAt least 2 years of alfalfa or other perennial crops in a 4 or 5 year rotation

    42 (12) Med-High Low

    Iowa Nutrient Reduction Strategy, 2014

    Be

    st

    B

    ette

    r

    Go

    od

    http://www.nutrientstrategy.iastate.edu/sites/default/files/documents/NRSfull-141001.pdf

  • Septic systems and nitrate

    Robertson and Harman 1999

    • Designed to dispose of human waste in a manner that prevents bacteriological contamination of groundwater supplies.• Do not effectively remove all contaminants from wastewater: Nitrate, chloride, viruses?, pharmaceuticals?, hormones? • One person excretes 11 pounds of nitrogen per year (Tchobanoglous, 2010)

  • Comparing Land-use Impacts

    Corn1

    (per acre)Prairie1

    (per acre)Septic 2

    System

    Total Nitrogen Inputs (lb) 169 9 20-25

    Nitrogen Leaching Loss (lb) 32 0.04 16-20

    Amount N lost to leaching (%) 19 0.4 80-90

    1 Data from Masarik, 20142 Data from Tri-State Water Quality Council, 2005 and EPA 625/R-00/008

  • 32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    20 lbs

    Comparing Land-use Impacts

    32 lbs/ac x 20 acres = 640 lbs14 mg/L

    20 lbs/septic system x 1 septic systems = 20 lbs1/32nd the impact on water quality

    0.44 mg/L

    20

    acr

    es

    20

    acr

    es

    Assuming 10 inches of recharge

  • 20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    20 lbs 20 lbs 20 lbs 20 lbs

    Using these numbers: 32 septic systems on 20 acres (0.6 acre lots) needed to achieve same impact to water quality as 20 acres of corn

    Comparing Land-use Impacts

    32 lbs/ac x 20 acres = 640 lbs 20 lbs/septic system x 32 septic systems = 640 lbs

    20

    acr

    es

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    32 lbs 32 lbs 32 lbs 32 lbs

    20

    acr

    es

  • Our nitrate challenge:The top foot• Current agricultural systems allow for significant

    nitrate losses to groundwater – much of it can occur outside the growing season

    • Soils and geologic considerations can exacerbate losses from agricultural systems

    • Future management priorities/challenges:• 1) Encourage but also need to better quantify nitrate

    reduction from different management strategies• Cover crops• Diversification of crop rotations• Etc.

    • 2) Climate change will impact nitrate losses to groundwater

    • More extreme rainfall events• Longer growing season• Increased soil temperature

    • 3) Be more intentional about residential development with private wells in rural areas/subdivisions

    • Proximity to agricultural areas• Density of septic systems

  • Kevin [email protected]

    mailto:[email protected]

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