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Description:
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Concentrated animal feeding operations (CAFOs ) have caused water quality
concerns in many rural watersheds , sometimes forcing the State of Texas to conduct
Total Maximum Daily Load (TMDL ) assessments of stream nutrients such as nitrogen
(N ) and phosphorus (P ) . One suggested Best Management Practice (BMP ) is the export
of phosphorus (P ) through turfgrass sod produced with composted dairy manure from an
impaired rural watershed to an urban watershed . The manure -grown sod releases P
slowly and would not require additional P fertilizer for up to 20 years in the receiving
watershed . This would eliminate P application to the sod and improve the water quality
of urban streams .
The Soil and Water Assessment Tool (SWAT ) was used to model a typical
suburban watershed that would receive the transplanted sod . The objective of the
modeling was to determine the water quality changes due to the import of sod
transplanted from turf fields and grown with composted dairy manure . The SWAT model
was calibrated to simulate historical flow and sediment and nutrient loading to Mary's
Creek . The total P stream loading to Mary's Creek was lower when manure -grown sod
was imported instead of commercial sod grown with inorganic fertilizers . Yet , flow ,
sediment yield , and total N yield increased equally for both cases at the watershed outlet .
The SWAT simulations indicate that a turfgrass BMP can be used effectively to import
manure P into an urban watershed and reduce in -stream P levels when compared to sod
grown with inorganic fertilizers . |