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The Management of Soil Phosphorus Availability and its Impact on Surface Water Quality
Published in R. Lal, B. A. Stewart, Soil Processes and Water Quality, 2020
The loss of P in subsurface runoff is appreciably lower than that in surface runoff, because of sorption of P from infiltrating water as it moves through the soil profile (Table 5). Subsurface runoff includes tile drainage and natural subsurface runoff, where tile drainage is percolating water intercepted by artificial drainage systems, such as tile or mole drains, thus accelerating its movement into streams. In general, P concentrations and losses in natural subsurface runoff are lower than in tile drainage (Table 5), due to the longer contact time between subsoil and natural subsurface flow than tile drainage, enhancing SP removal. Increased sorption of P from percolating water also accounted for lower TP loads from 1.0 to 0.6 m deep tiles draining a Brookston clay soil under alfalfa (Figure 17, from Culley et al., 1983). For the shallower drains, TP loads were about 1% of fertilizer P applied, whereas 1 m deep tiles exported about 0.6% of that applied (Figure 17).
Event-Driven Systems
Published in Robert H. Kadlec, Treatment Marshes for Runoff and Polishing, 2019
Agricultural stormwater occurs as runoff from crops and pastures. Non Point Source (NPS) pollution from agriculture may occur when nutrients are applied at rates greater than crops can utilize or when timing of nutrient applications occurs in close proximity to heavy rains (Stone et al., 2003). A fraction of the fertilizers applied to fields is unavoidably lost to runoff and shallow groundwater. Tile drainage systems collect subsurface waters, and vent them to receiving streams, where their nitrogen content, together with phosphorus, may cause problems. Wetlands are being used at various points in the agricultural landscape, corresponding to drainage areas ranging from individual fields (U.S. Department of Agriculture, 1991; Tanner et al., 2003), to small order streams (Stone et al., 2003), to large regional landscape units of thousands of hectares (Reilly et al., 2000). Some of these receive pumped water at relatively constant rates, and these have been included under the discussion of continuous (but possibly variable) flow wetlands. Those that receive water as a result of meteorological events are considered here.
The past, present, and future of blind inlets as a surface water best management practice
Published in Critical Reviews in Environmental Science and Technology, 2020
Chad Penn, Javier Gonzalez, Mark Williams, Doug Smith, Stan Livingston
Drainage of closed depressions is often accomplished using a combination of surface and subsurface (tile) drainage. A surface inlet is typically placed at the lowest elevation within the depression and routes ponded water directly to the subsurface drainage network, whereas subsurface drainage lines aid in lowering seasonally perched water tables. Ponded and subsurface water is subsequently transported via the subsurface drainage network tens to thousands of meters to the nearest drainage ditch. It is estimated that the number of closed depressions with surface inlets in the Western Lake Erie Basin may exceed 75,000 (Feyereisen et al., 2015). In the Minnesota River Basin, more than 250,000 (1–11 per km2) closed depressions are farmed and likely drained (Mueller & Wehrenberg, 1994). Surface runoff draining through the surface inlet to the tile drainage network has the potential to transport sediment, nutrients, and pesticides directly from fields to receiving waters. Research in the St. Joseph River watershed in Indiana demonstrated that the relative area of closed depressions within the watershed was correlated with the amount of phosphorus (P) conveyed to agricultural drainage ditches (Smith et al., 2008). Tomer et al. (2010) also reported that surface inlets contributed 50% of the total P in the Tipton Creek watershed in Iowa.