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Description:
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A total maximum daily load (TMDL ) assessment in the Upper North Bosque River (UNBR ) has mandated reductions of soluble reactive phosphorus (SRP ) . The large concentrations of dairies in the UNBR watershed have been identified as a source of the SRP . Agricultural best management practices (BMPs ) can be used to reduce in -stream loads of manure nutrients from confined dairy feeding operations (CAFOs ) . A new BMP utilizes turfgrass sod to export composted dairy manure nutrients out of the impaired watershed in a sustainable manner . Previous plot -scale experiments have showed that 46 to 77 % of applied phosphorus (P ) and 36 to 47 % of applied nitrogen (N ) were removed in a single sod harvest . Two , 1 .4 ha turfgrass fields were instrumented to measure runoff flow and sediment and nutrient transport . One turfgrass field was topdressed with composted dairy manure and fertilizer N and the other with fertilizer N only . A total of 3 .5 % of the applied manure P and 3 .1 % of applied manure N were lost in the surface runoff over a 1 .5 year period . The runoff data from the experimental fields were used to calibrate and validate Soil and Water Assessment Tool (SWAT ) model simulations of flow , sediment , organic , and mineral nutrients . The Nash -Sutcliffe model fit statistic was greater than 0 .6 for flow , sediment , and nutrients during the calibration period and greater than 0 .3 during the validation period . Research results indicated that turfgrass sod can be used to export composted dairy manure out of impaired watersheds to improve water and soil quality . |