Drainage Water Management

In-Field, Edge-of-Field and Beyond-the-Field: Management of Water for Achieving Agricultural Production and Environmental Quality Goals

Diagram showing the geographic locations of edge-of-field bioreactors, in-stream ditches, edge-of-field constructed wetlands, and in-field cropping systems management.

Agricultural production is intensifying to meet the increased demands on food security, availability, and accessibility caused by global population growth. Climate and land use changes place stress on land and water resources. Opportunities for sustainable intensification of agricultural production, which include water management strategies, have never been greater.

Crops vary in their tolerance to excess- and deficit-water stress. In humid regions, excess and deficit water conditions can occur during the same growing season, making managing soil water conditions difficult. Periods of excess water make artificial drainage essential to allow timely field work and aeration of the root zone during the growing season. Water deficit, mainly during summer, is one of the primary reasons that crops fall short of their yield potential.

Our research includes multiple water management approaches to address these issues:

Drainage

In much of the Midwestern US, including Minnesota, land use is dominated by row crop agriculture with the extensive use of artificial subsurface drainage systems (a.k.a. “tile” drainage) and maintained ditches to manage soil water conditions. The severity and duration of excess water in the root zone of plants can affect soil physical, chemical, and biological properties as well as plant growth and development.

Excess water is a serious constraint, lowering the production and productivity of corn, soybean, and small grains. It creates a need for surface drainage due to water ponding on the soil surface. It creates a need for subsurface drainage caused by water-logging, a high water table, or soils with low permeability. Drainage provides a pathway for excess or drainable water to be removed from the soil. Surface and subsurface drainage systems have enabled agricultural production on much of the most productive lands in the world.

Drainage has been and will continue to be an essential component of agricultural production. As the demand for increased food production on limited land resources grows, coupled with achieving environmental quality goals, the need for sound drainage research will continue to be important. The greatest challenge for drainage system design and management is to reduce downstream impacts due to losses of nitrogen and phosphorus in drainage outflows.

Precise management of agricultural drainage water using in-field, edge-of-field, and beyond-the-field strategies represent a significant step forward for agriculture. The benefits reach from conserving subsoil moisture on individual subsurface drained fields to reducing nutrient loading in lakes, rivers, and sensitive coastal estuaries.

Cottonwood River Watershed

The University of Minnesota Southwest Research and Outreach Center is located near Lamberton, MN in the Cottonwood River Major Watershed. Farming is the principal segment of the economy in this watershed, consisting primarily of row crop production of corn and soybeans. Land cover in the watershed consists of approximately 85% cultivated cropland, 8% grassland (including CRP land), 1% woodland, and 6% other land. The watershed landscape is characterized as having a complex mixture of gently sloping (2-6% slope) well drained loamy soils and nearly level (0-2% slope) poorly drained loamy soils formed in glacial till. Artificial drainage to remove ponded-water from flat and depressional areas is extensive. Poorly drained soils are highly productive due to an extensive network of subsurface tile drainage and open-ditches.

Cottonwood watershed in southwest Minnesota