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18th World Congress of Soil Science
July 9-15, 2006 - Philadelphia, Pennsylvania, USA |
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The loss of phosphorus (P) from manure-amended agricultural fields can be exacerbated by drainage ditches. This study involved the monitoring of surface and sub-surface pathways of P transport on a coastal-plain farm with a 25 to 30 year history of intensive poultry litter application and elevated soil nutrient levels. Preliminary results indicate that the export of P from drainage ditches was high (up to 40 kg/ha/yr), primarily in storm flow, which accounted for 70-99 of annual flow and 75-97% of annual P export. Surface runoff accounted for only 5-22% of annual ditch flow, pointing to subsurface flow and ditch soils as primary sources of exported P. In addition to improved manure management, opportunities exist to substantially reduce P losses through the precision application of innovative soil and ditch management practices.