Investigating nitrate dynamics in a fine-textured soil affected by feedlot effluents.
Feedlots concentrate large volumes of manure and effluents that contain high concentrations of nitrate, among other constituents. If not managed properly, pen surfaces run-off and lagoons overflows may spread those effluents to surrounding land, infiltrating into the soil. Soil nitrate mobilization and distribution are of great concern due to its potential migration towards groundwater resources. This work aimed at evaluating the migration of nitrate originated on feedlots effluents in a fine-textured soil under field conditions. Soil water constituents were measured during a three-year period at three distinct locations adjacent to feedlot retention lagoons representing different degrees of exposure to water flow and manure accumulation. A simple statistical analysis was undertaken to identify patterns of observed nitrate and chloride concentrations and electrical conductivity and their differences with depth. HYDRUS-1D was used to simulate water flow and solute transport of Cl-, NO4+N, NO3-N and electrical conductivity to complement field data interpretation. Results indicated that patterns of NO3-N concentrations were not only notoriously different from electrical conductivity and Cl-but also ranges and distribution with depth differed among locations. A combination of dilution, transport, reactions such as nitrification/denitrification and vegetation water and solute uptake took place at each plots denoting the complexity of soil-solution behavior under extreme polluting conditions. Simulations using the concept of single porosity-mobile/immobile water (SP-MIM) managed structural controls and correctly simulated-all species concentrations under field data constrains. The opposite was true for the other two locations experiencing near-saturation conditions, absence of vegetation and frequent manure accumulation and runoff from feedlot lagoons. Although the results are site specific, findings are relevant to advance the understanding of NO3-N dynamics resulting from FL operations under heavy soils.
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, (C1033AAJ) Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Hidroambientales (CENEHA)-Facultad de Ingeniería y Ciencias Hídricas (FICH)-Universidad Nacional del Litoral (UNL), Ciudad Universitaria. Ruta Nacional N° 168 - Km 472,4, (3000), Santa Fe, Argentina. Electronic address: veizaga.e82@gmail.com.
E A
EA
Veizaga
Centro de Estudios Hidroambientales (CENEHA)-Facultad de Ingeniería y Ciencias Hídricas (FICH)-Universidad Nacional del Litoral (UNL), Ciudad Universitaria. Ruta Nacional N° 168 - Km 472,4, (3000), Santa Fe, Argentina.
L
L
Rodríguez
School of Civil, Environmental and Mining Engineering, University of Western Australia, 35 Stirling Highway, 6009 Crawley, Western Australia, Australia.
C J
CJ
Ocampo
D000821:Animal Feed; D000822:Animal Husbandry; D058440:Denitrification; D004784:Environmental Monitoring; D004787:Environmental Pollution / Q000032:analysis*; D060587:Groundwater / Q000737:chemistry; D008372:Manure; D008956:Models, Chemical; D009566:Nitrates / Q000032:analysis / Q000737:chemistry*; D058465:Nitrification; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D062065:Wastewater / Q000032:analysis / Q000737:chemistry*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
D008372:Manure; D009566:Nitrates; D012987:Soil; D012989:Soil Pollutants; D062065:Wastewater; D014874:Water Pollutants, Chemical
Feedlot; Nitrate; Numerical model