2007 Annual Report 1a.Objectives (from AD-416) An assessment of the transport and fate of nitrate and indicator microorganisms at dairy lagoon water application sites that are following a well designed and rigorous implemented comprehensive nutrient management plan (CNMP). 1b.Approach (from AD-416) Analyze and numerically model the collected transport data, as well as measure or estimate associated transport and fate parameters. Provide field, laboratory,and modeling studies to investigate the performance of CNMPs at lagoon water application sites. Documents Reimbursable with EPA. Log 28132. Formerly 5310-32000-001-04R (6/05). 3.Progress Report This section serves to document progress on the interagency agreement between the US EPA and the USDA-ARS Salinity laboratory entitled “Transport and fate of Nitrate and pathogens at a dairy lagoon water application site: An assessment of CNMP performance”. Detailed progress reports are required quarterly for this project by the EPA and the interested reader is referred to these documents for a full description of this work. In brief, we have heavily instrumented two 5x5 m field plots for fate and transport studies. During the past year we have implemented a Comprehensive Nutrient Management Plan at these sites using dairy lagoon water as the nutrient source in combination with well water. Three crops have been considered: Sudan grass (October-November of 2006), a Rye-Barley hybrid (Winter of 2007), and Sorghum (Summer of 2007). Two irrigation strategies have been studied, namely: Cyclic and Blending application strategies. We have found that nitrogen leaching from the root zone and soil nitrogen utilization was more efficient using the Blending than the Cyclic strategy. This is likely due to advanced overdose of the nutrients supply to the soil as part of the Cyclic strategy practice, whereas Blending supplies the nutrients as needed by the crop. The transport of E. coli., Fecal coliform and coliphage X174 was very limited in the soil at the CNMP sites. No trace of these microorganisms was found in the soil solution below 30 cm deep. Therefore, frequent sampling of soil cores from the upper 15 cm was collected and analyzed for their concentration over depth and time. An exception was Enterococcus, which was found initially in high concentrations along the soil profile and did not changed significantly over time. We attribute this observation to the enhanced survival ability of this bacterium over the other considered microorganisms. Comparison between the Blending and Cyclic treatments reveals that E. coli., Fecal coliform and X174 were found in both soils profiles near the surface (30 cm depth), however the concentration and penetration depth was significant higher in the Cyclic treatment. This observation can likely be attributed to the enhanced survival ability of these microorganisms due to the higher organic load that was initially applied with the Cyclic treatment. Additional research is planned to further explore these issues. Other mathematical modeling studies and colloid/tracer experimental studies that are related to this work have also been conducted over the past year.