Effects of Immobilizing Agents on Surface Runoff Water Quality from Bermudagrass Sod Fertilized with Broiler Litter

Author(s): Sheng, J.; Adeli, A.; Brooks, J.; McLaughlin, M.

Surface broadcasting is the common method for applying poultry litter on perennial forages, but this application method concentrates nutrients and pathogenic microorganisms at the soil surface where they are vulnerable to runoff water. The potential impairment of surface water from soluble nutrients, particularly N and P, metals such as copper (Cu) and Zinc (Zn), and pathogenic microorganism contained in broiler litter are of concern. Management practices that minimize contaminants in surface runoff water are environmentally desirable. A greenhouse study was conducted using rainfall simulation to determine the effects of immobilizing agents, such as FGD (flue gas desulfurization) gypsum (a residue from coal combustion) and biochar, on manure nutrients and fecal bacteria in runoff from bermudagrass sod. The experimental design was a randomized complete block with seven treatments and three replications. Treatments included a control (no litter), and broiler litter (either wood shavings or rice hulls) at the rate of 9 Mg ha-1, in all combinations with and without FGD or biochar. Rainfall was delivered at an average intensity of 75 mm h-1 with a total of four rain events. Runoff was collected in 250-ml sterile plastic bottles. Runoff samples were immediately transferred to the lab for microbial and nutrient analyses. Nitrate and ammonium were determined on a Lachat. Dissolved reactive P and metals were determined in filtered (0.45 µm filter) runoff samples. Unfiltered runoff samples were digested and analyzed for total nutrient concentrations using ICP). The results indicated that application of broiler litter in combination with FGD gypsum to bermudagrass significantly reduced runoff total dissolved organic C (DOC), total N, dissolved reactive P (DRP), Cu and Zn by 16, 30, 61, 73 and 13%, respectively, compared to broiler litter alone, regardless of litter type. Biochar had no effect on reducing soluble nutrients in surface runoff. Treatments did not affect culturable bacterial levels in runoff. Detailed information will be discussed.

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Technical Sessions

1 Best Management Practices #1
2 Delta Water Assessment
3 Flood Assessment & Mgmt.
4 Wetlands
5 Watershed Mgmt. #1
6 Non-Point Source Assessment
7 Modeling
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10 Delta Water Conservation
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13 Watershed Mgt. #2
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