2002 Annual Report
Research
Environmental and Agronomic Impacts of Subsurface Drainage Design
Gary Sands, Assistant Professor
Lowell Busman, Extension Educator, Southern Research and Outreach Center,
Lamberton, MN
Bradley Hansen, Assistant Scientist
Chang-Xing Jin, Research Associate
Aida Mendez, Research Associate
Funding Source
Minnesota Land Improvement Contractors of America; Minnesota Department
of Agriculture; Minnesota Agricultural Experiment Station; Minnesota Corn
Research and Promotion Council; Cargill; Prinsco, Inc.; Advanced Drainage
Systems, Inc.; Hancor; Hawkeye Tile
Objective
Determine the water quality, hydrologic, and agronomic impacts of alternative
depth and spacing criteria for subsurface drainage.
Project Description
Pattern tiling of agricultural fields continues to be a common practice
in Minnesota, especially within the 10 million-acre Minnesota River Basin.
The drainage industry estimates that over 100 million feet of drainage
tile were installed throughout Minnesota in 1997, with similar rates in
1998. Many farmers have seen such a positive response from tile drainage
that they are installing tile at one-half the recommended tile spacing,
and sometimes narrower. Modeling research suggests that more intense drainage
(deeper and narrower spacing) may exacerbate losses of nitrate-nitrogen
from drainage systems. This research seeks to understand the impacts of
design considerations (depth and spacing) on hydrology, water quality,
and crop response, for a variety of soils and landscape positions. Surface
and subsurface flow, nitrates, sediment, and phosphorus are being measured
and compared between the controlled and uncontrolled plots and compared
to undrained conditions. Other measurements include water table elevations,
soil temperature, and soil moisture. Modeling efforts are underway to
evaluate the performance of drainage design scenarios over longer time
frames.
Results
Data from 2001 and 2002 suggest that subsurface drains placed at shallower depths (e.g., 3 ft. instead of 4 ft.) can substantially reduce annual subsurface drainage volumes and nitrate losses. Computer simulation is being undertaken to extend these results to other soil types and longer climatic records.