Comparison of Free Drainage, Controlled Drainage, and Subirrigation Water Management Practices in an Ohio Lakebed Soil
2004, Ottawa, Canada August 1 - 4, 2004
Agricultural drainage is an essential management practice for farmers and ranchers in order for them to achieve economically viable production levels in humid regions with slowly permeable soils and in arid irrigated regions. Historically, drainage systems have been installed and allowed to function by relying on gravity or pumping to convey all the water that reached the pipes and ditches away from the area needing the drainage improvement. Over time it has become apparent that there are
... hat there are offsite effects caused by drainage waters and their constituents. Drainage effluent is now known to increase the quantity of offsite flows and to contain soluble nutrients, agrichemicals, or salts that can negatively impact the receiving stream or water body. Environmental and ecological impacts may result from these pollutants such as increased flooding, lake eutrophication, development of hypoxic zones, loss of habitat, reproductive failures in wildlife species, and contamination of drinking water supplies. Control of subsurface drainage system outlets is a recommended water quality BMP in North Carolina to protect the Neuse River estuary system, and is perceived to provide at least a partial solution for hypoxia in the Gulf of Mexico if applied widely throughout the Mississippi River basin. A replicated field plot experiment was conducted to examine the hydrology, water quality, and crop yield impacts of controlled drainage, uncontrolled drainage, and subirrigation drainage on Hoytville silty clay soil in Ohio. Drainage volume, nitrate content of drainage water, nitrate content of vadose zone water, and crop yields were measured to compare and contrast the water management treatment impacts. Controlled drainage resulted in less water and nitrate released offsite and a lower concentration of nitrate in the vadose zone water than with uncontrolled drainage. Control of drainage outlets to manage drainage discharges and water quality will necessitate changes in the design and installation of drainage systems. Some research and educational programs will be required to encourage this new approach to drainage management and to assist growers to understand and apply the additional management skills that will be required.