Agricultural Drainage 101: Part 4 · 2012-10-04 · Agricultural Drainage 101: Part 4 Author: Dr. Craig Schrader Subject: Drainage presentation for Lake Pepin SAC: July 20, 2006 Keywords:

Impacts of Drainage

Hydrology

Water Quality

Aging Infrastructure

“Stages” of DrainageNative prairie grasses, wet landscape, high evaporation and transpiration rates

(late 1800’s – 1920’s) Conversion to agriculture w/ early drainage, targeted ditching,

Continued ditching, targeted tiling, surface inlets in depressions, more intensive row cropping

(late 60’s – early 70’s) Advent of plastics, drain plows, large pattern drainage projects, fewer crops in rotation

(current) replacement of old tile, intensification on previously drained fields

Impacts from What Type of Drainage?

Subsurface Drainage

Surface Drainage

The Impacts of Tile Drainage . . .With Artificial Drainage

Increased nitrate-nitrogen lossesLower peak flows, higher sustained low flowsFewer temporary wetlands

N has about 9.5 million acres remaining (~50%)

Aging and repair of undersized infrastructureProductive ag lands benefit local and state levels

Without Artificial DrainageIncreased sediment & phosphorus lossesHigher peak flows, more localized floodingMore temp wetlands

Increased habitat

Depend on natural drainage-ways only“Income” derived from other ecological services

Water Quality Concern (Nitrogen)

Drinking Water

Quality

Hypoxia in the Gulf of Mexico

Cost of N Losses

Hypoxia/Anoxia of Coastal SystemsHypoxia (low oxygen) in coastal ecosystems is impetus behind research

Systems very complex

Coastal systemsnitrogen limiting

Upper Midwestresponsible formuch nitrate

Recent concernover role of P

Nitrogen by Drainage Basin

2002 estimated nitrate/nitrite loading:

960,000 metric tons(12th highest in 22 yrs)

Loss of WetlandsSociety placing higher value

Drainage increasingly associated with loss of wetlands States with notable wetland loss (1860-1900)

Swamp land act acres granted

WhatWhat’’s Being Done?s Being Done?

New Drainage “Mantra”

Drain only that which is necessary to ensure

trafficability and crop production …

—and not a drop more!

Drainage Research….on Location

Crookston & BrooksCrookston & Brooks

Tilney & Red Top FarmsTilney & Red Top Farms WasecaWaseca

St. PaulSt. Paul

LambertonLamberton

MorrisMorris