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United States Department of Agriculture

Agricultural Research Service

Title: Management Practice Effects on Phosphorus Losses in Runoff in Corn Production Systems

Authors
item Bundy, L - UNIVERSITY OF WISCONSIN
item Andraski, T - UNIVERSITY OF WISCONSIN
item Powell, J Mark

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2001
Publication Date: N/A

Interpretive Summary: Phosphorus (P) losses in runoff from cropland can contribute to the pollution of surface waters. Management practices typically used to produce corn may influence how much P is lost in runoff. This study was conducted to determine the influence of typical farmer management on P in runoff. Field experiments were conducted at Arlington and Madison, Wisconsin on a prominent silt loam soil with previously-established treatments including various soil test P levels, tillage and manure application combinations and manure and biosolids application histories. Runoff from simulated rainfall was collected from small (0.83 m**2) plots for 1 hr after rainfall initiation and analyzed for dissolved reactive P (DRP), bioavailable P, total P (TP), and sediment. In a no-till corn system, both DRP concentration and load increased significantly as soil test level increased. A 5-yr history of manure or biosolids application greatly increased STP and DRP concentrations in runoff relative to the control. The 5-yr manure treatment had higher DRP concentration levels but lower DRP load than the 5-yr biosolids treatment at similar total P P additions, likely due to residue accumulation and lower runoff in the manure treatment. Studies of tillage and manure application effects on P losses in runoff showed that no tillage and unincorporated manure increased DRP concentrations, did not consistently affect DRP loads, and significantly decreased TP concentration and loads in runoff. Tillage to incorporate manure lowered runoff DRP concentration but increased TP concentration and loads due to increased sediment loss. Extension agents can use these messages to show farmers that management practices have a major influence on P losses in runoff in corn production systems.

Technical Abstract: Phosphorus losses in runoff from cropland can contribute to pollution of surface waters. Management practices typically used in corn production systems may influence P losses in runoff. This study was conducted to determine the influence of typical management on P concentrations and loads in runoff. Field experiments at Arlington and Madison, Wis. on silt loam soils (fine-silty, mixed, mesic Typic Argiudolls) with previously-established treatments. Runoff from simulated rainfall (76 mm/hr) was collected from 0.83 m2 areas for 1 hr after rainfall initiation and analyzed for dissolved reactive P (DRP), bioavailable P, total P (TP), and sediment. In a no-till corn system, both DRP concentration and load increased significantly as Bray P1 soil test (STP) level increased from 8 to 62 mg/kg. A 5-yr history of manure or biosolids application greatly increased STP and DRP concentrations in runoff relative to the control. The 5-yr manure treatment had higher DRP concentration but lower DRP load than the 5-yr biosolids treatment at similar total P additions, likely due to residue accumulation and lower runoff in the manure treatment. Studies of tillage and manure application effects on P losses in runoff showed that no tillage and unincorporated manure increased DRP concentrations, did not consistently affect DRP loads, and significantly decreased TP concentration and loads in runoff. Tillage to incorporate manure generally lowered runoff DRP concentration but increased TP concentration and loads due to increased sediment loss. Results from this work showing that some practices may have opposite effects on DRP vs. TP losses, emphasize the need to design management recommendations to minimize losses of those P forms with the greatest pollution potential.

Last Modified: 7/28/2014
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