Tile Drainage Systems Management and Conservation

The amount of U.S. crop acreage drained by subsurface tile systems increased by approximately 18 million acres from 1980 to 2022. Tile drainage can increase crop productivity in fields with poorly drained soils and can be a valuable long-term investment. However, installing tile drainage alters the hydrology of farm fields and can promote the leaching of nitrate-N and dissolved reactive phosphorus to downstream waters. Using the data from the U.S. Department of Agriculture’s Census of Agriculture, Agricultural Resource Management Survey, and administrative records, this report details trends in tile drainage usage, as well as the joint adoption of tile drainage and other management practices. Tile drainage systems can involve a suite of conservation practices that are eligible for financial assistance through USDA programs. Tile drainage remains a prominent practice on corn and soybean acreage and is increasing in use on acreage dedicated to oats or cotton. There are significant differences in nutrient management practices on tiled drained and non-tiled fields. Without controlling for other factors, data for all corn acres reveal a higher rate of nutrient application, greater use of fall application, and higher usage of nitrification inhibitors on tiled-drained acres compared to non-tiled acres. Subsurface control structures, saturated buffers, and other conservation practices that manage subsurface outflows remain uncommon throughout our sample period.