2008 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 In brief, during the 2006-2007 we have implemented a Nutrient Management Plan (NMP) at two 5x5m plots 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. The NMP was based on measured information for water and nitrogen mass balance in the root zone during each irrigation event. The field site was heavily instrumented to monitor evapotranspiration (ET) and precipitation rates, irrigation amount and uniformity, and soil water status and composition with depth and time. The nutrient composition of the lagoon water , the uptake rate of nitrogen by the plants, nitrogen losses to the atmosphere and by leaching, nitrogen transformation rates, and the transport and fate of salts in the root zone were also measured. Execution of an efficient NMP required water application to meet ET demands, and pretreatment of the dairy lagoon water to lower the organic N and increase the fraction of inorganic N in the irrigation water. Under these conditions nitrate and ammonium were mainly removed by plant roots during the growing season and losses due to drainage were minimal. However, salt that accumulated in the root zone may influence subsequent crop yields and soil quality. A pre-irrigation was used to leach these salts below the root zone, but this resulted in the flushing of nitrate that was mineralized during the fallow period. This observation suggests that NMPs shoud be based primarily on inorganic N forms and that have low values of organic N in CAFO wastewater and soils, and that leaching of salts should occur at the end of the growing season. The subsurface transport and survival of indicator microorganisms (total E.coli, fecal coliforms, Enterococcus, and somatic coliphage) in the lagoon water were also studied under these NMP conditions. When crops were irrigated using sprinklers at a rate that was 25% of the saturated soil conductivity, little transport of the indicator microorganisms was observed. Survival in the root zone was highly dependent on the microorganism type, with high survival rates for Enterococcus and much lower survival rates for total E. coli, fecal coliforms, and somatic coliphage. Complimentary laboratory column transport experiments were also initiated using repacked and undisturbed field soil. These experimental studies and corresponding numerical modeling demonstrate the potential importance of irrigation regime, soil texture, and soil structure on microorganism transport and survival. On October 22, 2007 we had some severe winds that caused extensive damage to our San Jacinto field research site. Hence, we spent considerable amounts of time to clean and repair the field NMP site during November 2007 through April 2008. Drs. Bradford and Simunek coordinate the work schedules for personnel that are hired through this project and meet with them on a monthly basis to discuss research plans.