Conservation Drainage: Drainage for the 21st Century

1890s The Nitrate Saga Scientists sound alarm about need for new source of nitrates

Carl Bosch Fritz Haber

Nutrient contributions to the Gulf, by State

Distribution of Subsurface Tile Drainage in Illinois 3-4 million ha (6-10 million acres) drained with subsurface tile in Illinois This comprises some of the most productive agricultural land in the US.

HYDROLOGIC CYCLE (with tiles) While the water drains into the drain pipes, its is simultaneously discharged to the stream through a network of pipes. This section here, shows some important hydrologic processes where the drain meets the stream or the ditch. There is also a significant amount of water drained through the ditch sides through interflow process, all along the ditch. And of course the water that remains undrained, flows as surface runoff towards the streams as well.

7.2 km/km2

The solutions that you seek will not be found in the streak of a pen, or even one thousand words of mine. Mutabaruka

Nitrate Reduction Techniques Altering Nitrogen Application Amounts Altering Nitrogen Application Timing Edge-of-Field Treatment Optimizing Drainage System

Conservation Drainage Minnesota Department of Agriculture The incorporation of environmentally friendly practices and structures into existing drainage infrastructure Conservation Drainage has been defined as “The incorporation of environmentally friendly practices and structures into existing drainage infrastructure.” In essence this means the optimization of drainage practices for both production and water quality objectives. Minnesota Department of Agriculture

Conservation Drainage The optimization of drainage systems for crop production, water quality and water harvesting benefits

No Decrease in Drainage Efficiency No Adverse Effects on Neighbors Water Management No Decrease in Drainage Efficiency No Adverse Effects on Neighbors Conservation Drainage Subsurface Bioreactors With drainage being such an important part of agriculture in Illinois, we have been at the forefront of conservation drainage research. The focus has been on three practices with increasing potential in terms of applicable acreage: Drainage Water Management, Passive Subsurface Bioreactors, and Depth/Spacing Modifications It is important to note that we have been conducting our research under self- imposed constraints. Conservation practices should not lead to a decrease in drainage efficiency, There should be no adverse effects of surrounding farmers and other neighbors, and The practices should be convenient and cost effective. We believe that these constraints will lead to more widespread adoption of these practices. I would like to share with you the results of some of the work that we are doing in these three areas. Depth/Spacing Modifications Convenient and Cost-Effective

Golden Rule of Drainage Only release the amount water necessary to insure trafficable conditions for field operations and to provide an aerated crop root zone any drainage in excess of this rule likely carries away nitrate and water that is no longer available for crop uptake

Drainage Water Management

Manual Gate Structure Automated Gate Structure Float Structure

Drainage Water Management Guidelines – in an unusually dry season, control can be 3 to 6 inches higher; – in an unusually wet season, control should be 3 to 6 inches lower; – in coarse-textured soils, trafficability can be provided with the water table approximately 6 inches higher.

Managed Drainage - Winter Conservation Mode for Fallow Season

Managed Drainage - Spring Full Drainage Mode for Planting Season

Managed Drainage -Summer Shallow Drainage Mode for Growing Season

Managed Drainage - Fall Full Drainage Mode for Harvest Season

Potential Water Available from Drainage Management ~ 1.5 inches Source: Based on DRAINMOD Simulations

Water Deficit Stress

DWM Benefits Reduces Nitrate Concentrations in Effluent 30-95% reductions annually Increased Yield 76% higher yield in a dry year Lower Concentrations of Other Pollutants

Required Information for Economic Analysis of DWM System Drainage Costs Added Revenue Capital Costs Timeliness Benefits Schematic of proposed field-scale bio-filters. The bio-filter is teed off of an existing tile. It consists of one or more cells placed below the level of the tile. The water flows up through the bio-filter and out the outlet pipes. The outlet tile is below the level of the existing tile, thus water preferentially flows through the outlet. However, if the capacity of the bio-filter is exceeded, water will flow through the existing tile. Thus the drainage effectiveness is not reduced by the addition of a bio-filter. In the systems that we have installed, the bottom of the bio-filter trench is 12 to 24 inches below the tile invert. The important thing is that the volume of the bio-filter should be enough to achieve an 8-hour retention time.

Drainage Water Management 29

Hume 2004 30

Flow Depths (cm) From a Paired Drainage Site Free Drainage Managed Drainage 31

Hume 2006 32

Long Term Nitrate Trends: 2005 High levels of variation throughout year. Managed Drainage and free drainage systems show similar response and variability.

Long Term Nitrate Trends: 2008 Nitrate concentrations continue to be lower on average for the managed drainage case. They can still be above the MCL.

Free Drainage 11.3 acres 50-70 ft Spacing Managed Drainage 13.1 acres 50-70 ft Spacing

Kinderhook Site Nitrate-N (mg/L)

System Layout for Drainage Water Management

Cost Differential: $50/acre Layout Costs Cost Differential: $50/acre