USDA is an Equal Opportunity Employer & Provider.

USDA is an Equal Opportunity Employer & Provider

Training OutlineBackground/Orientation – Pat Willey – Portland , OR WQQT

Drainage Systems – Hamid Farahani – Greensboro, NC ENTSC

DWM for Subsurface Systems – Ruth Book, SCE, Champaign, IL

DWM for Surface Systems – Jerry Walker, Ft. Worth, TX CNTSC

Wrap Up – Hamid Farahani

Ag Drainage Water Management Webinar August 2011

Drainage Water Management -Background/Orientation

1.MRBI Team and Ag Water Management Team

2.Basics of DWM

3.Downstream environmental impacts of Nitrogen and Phosphorus

– environmental issues– health issues

4.DWM requirement in N-Strategy 590 (where do we have to have it?)Ag Drainage Water Management Webinar

August 2011

Mississippi River Basin Initiative Team

Focus Area: Mississippi River Basin (AR, KY, IL, IN, IA, LA, MN,

MS, MO, OH, TN, and WI)

MRBI Goal:Improve Water Quality and wildlife habitat

through:Cooperative Conservation Partnership InitiativeWetlands Reserve Enhancement Program(WREP), Conservation Innovation Grants(CIG), and other programs

Ag Drainage Water Management Webinar

Senior Project Leader: Paul Sweeney

Team Membership are from the following:

NHQ Disciplines NHQ Program SpecialistsNTSC Representatives NRCS States

Team Advisors: (ARS, Purdue and NCSU)

Ag Water Management Team



Ag Water Management Team

• Scope is National

• Initial focus: Upper Mississippi River Basin

• Goal : reduce nitrate (NO3-1) loading to streams

reduce and ag. impact on Gulf of Mexico hypoxia

•How: Implement DWM to reduce NO3-1 leaving

drained farmlands

What is Drainage Water Management (DWM)?DWM- Practice Standard code 554 -

Employment of a Structure for Water Control (code 587) in the drainage line to provide capability to manage the flow from an agricultural drainage system.

DWM typically:• Involves raising the outlet elevation of a drain• Results in reduced flow from the outlet


Do structures eliminate flow from the drain outlet?Maybe…• When the outlet is initially raised, outflows

may stop.

• As flow continues to enter the drain upstream from the structure, the water table rises.

• Once the water level rises to the elevation of the raised outlet, any additional rise in the water table results in discharge to the outlet.


How can DWM help?DWM has been shown to reduce stream loading of

nitrates by agricultural drain systems

How much reduction in N-loading?

Reductions of 40% to 50% in nitrate have been achieved

Reductions are in proportion to reduction in drainage water out-flow (a 50% reduction in outflow may achieve a 40 to 50% reduction in N-load)


Why are we focusing on DWM?•NRCS recognizes nutrient loading to streams as a national concern

•Drainage water has been identified as a significant source of nutrient loads

•Impacts to Gulf of Mexico and other receiving waters are significantAg Drainage Water Management Webinar

August 2011

Does DWM affect crop growth?

• DWM on annual crops during the non-growing season does not adversely affect crop production

• Some production benefits may be observed by managing an elevated water table in the field during the growing season. Results are not statistically conclusive.


NRCS Expectations for DWM

• It is about management… not about draining new acres

• Focus is to manage drainage water for improved environmental outcomes and sustaining crop production

• Use a conservation systems approach—ADWM with nutrient management, conservation tillage, crop rotations, cover crops, etc.

• Consideration must be given to neighboring or downstream hydrologic effects —offsite lateral seepage, stream flows, flooding, groundwater


Environmental Impacts of Excessive Nutrients

• Hypoxia

• Drinking Water Quality


Hypoxia – the condition in which dissolved oxygen is below the level necessary to sustain most aquatic animal life.

Where is it a problem?

Notable hypoxic zones in the United States:

•Gulf of Mexico

•Chesapeake Bay

What is Hypoxia?


What causes Hypoxia?


Major process for hypoxia development of hypoxia in the Gulf

of Mexico1.Nutrient loading (nitrogen and phosphorus) to the Gulf by the Mississippi River (Mississippi provides 90% of fresh inflow to GoM)

2.Nutrient-enhanced primary production (enhanced growth of aquatic plants and protists (e.g. algae, diatoms) in the Gulf of Mexico

3.Plants and protists die and sink to the ocean floor.

4.Decomposition of biomass by bacteria on the ocean floor consumes oxygen dissolved in the water

5.Lack of mixing in water column maintains low oxygen levels near the ocean bottom


Hypoxic Conditions in the Northern Gulf of Mexico –

• defined as a concentration of dissolved oxygen less than 2 mg/L

• In other oceans of the world, the upper limit for hypoxia may be as high as 3-5 mg/L (species and temperature affect range)

• hypoxia develops near the ocean floor (affects bottom dwellers – shrimp, oysters, bottom fish)


Northern Gulf of Mexico (cont’d.):

• oxygen concentrations are stratified

• surface oxygen levels are typically >8 mg/L

• zone forms in spring; lasts until late Aug. or Sept.

•wind action by hurricanes (late summer) de-stratify the water column and return oxygen concentrations to normal


Human Health Concerns:Excessive levels of nitrate in drinking water can cause human health problems.

Short-term health effects: During digestion, nitrates transform to nitrites, which diminish the transfer of oxygen in the blood.


Methemoglobinemia (blue baby syndrome)

- a condition that results from high nitrites in the blood. This can be an acute condition in which health deteriorates rapidly over a period of days.

•Symptoms include shortness of breath and blueness of the skin.

• Results can be fatal

• Infants are particularly susceptible.Ag Drainage Water Management Webinar

August 2011

Environmental and Ecological Concerns:

Hypoxia and Low Dissolved Oxygen Effects –

• High aquatic species mortality

• Habitat loss

• Food chain alterations

• Loss of biodiversity

• Reproductive problems for fish

• Increased susceptibility to predationAg Drainage Water Management Webinar August 2011


Table 1. Estimates of annual nitrogen inputs in metric tons to the Mississippi River basin and its major tributaries

Source of Nitrogen

Mississippi Basin above Missouri River

All of Mississippi Basin

Metric Tons Percent of Total

Metric Tons

Percent of Total

Commercial fertilizer - all forms as N 1,898,800 54.3 5,873,800 50.6Livestock manure 914,100 26.1 3,451,300 29.7Legumes (soybeans and alfalfa) 375,500 10.7 1,031,900 8.9Atmospheric wet deposition of nitrate as N 107,700 3.1 512,300 4.4

Human domestic waste 188,600 5.4 627,800 5.4Industrial point sources 12,600 0.4 105,800 0.9Oxidized soil N ? ? Total 3,497,200 100.0 11,602,900 100.0Source: Goolsby and Battaglin, and Hooper,USGS. "Sources and Transport of Nitrogen in the Mississippi River Basin.

http://co.water.usgs.gov/midconherb/html/st.louis.hypoxia.html

Nitrogen

inputs in 1991

Source: Buxton, USGS.

Average stream yields

1980-1996


Ag Drainage Water Management Webinar

To qualify for financial assistance on NM 590...

•DWM required if land is drained, and DWM is feasible (feasibility based on slope, soil type, existence of pattern drainage, acres/economics)

• IWM is required if land is irrigated

•If both drained and irrigated, both of above required

Nutrient Management Strategy and DWM (National Bulletin: 450-11-4)

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