title: Vinasse application to sugar cane fields. Effect on the unsaturated zone and groundwater at Valle del Cauca (Colombia).
abstract: Extensive application of vinasse, a subproduct from sugar cane plantations for bioethanol production, is currently taking place as a source of nutrients that forms part of agricultural management in different agroclimatic regions. Liquid vinasse composition is characterised by high variability of organic compounds and major ions, acid pH (4.7), high TDS concentration (117,416-599,400mgL(-1)) and elevated EC (14,350-64,099μScm(-1)). A large-scale sugar cane field application is taking place in Valle del Cauca (Colombia), where monitoring of soil, unsaturated zone and the aquifer underneath has been made since 2006 to evaluate possible impacts on three experimental plots. For this assessment, monitoring wells and piezometers were installed to determine groundwater flow and water samples were collected for chemical analysis. In the unsaturated zone, tensiometers were installed at different depths to determine flow patterns, while suction lysimeters were used for water sample chemical determinations. The findings show that in the sandy loam plot (Hacienda Real), the unsaturated zone is characterised by low water retention, showing a high transport capacity, while the other two plots of silty composition presented temporal saturation due to La Niña event (2010-2011). The strong La Niña effect on aquifer recharge which would dilute the infiltrated water during the monitoring period and, on the other hand dissolution of possible precipitated salts bringing them back into solution may occur. A slight increase in the concentration of major ions was observed in groundwater (~5% of TDS), which can be attributed to a combination of factors: vinasse dilution produced by water input and hydrochemical processes along with nutrient removal produced by sugar cane uptake. This fact may make the aquifer vulnerable to contamination.
authors.affiliation: Grupo de Recursos Hídricos Dirección Técnica Ambiental, Corporación Autónoma Regional del Valle del Cauca, CVC, Cali, Colombia. Electronic address: gloria-isabel.paez@cvc.gov.co.
authors.forename: Gloria Páez
authors.initials: GP
authors.lastname: Ortegón
authors.affiliation: Centro de Investigación de la Caña de Azúcar de Colombia, CENICAÑA, Colombia. Electronic address: fmunoz@cenicana.org.
authors.forename: Fernando Muñoz
authors.initials: FM
authors.lastname: Arboleda
authors.affiliation: Department of Geotechnical Engineering and Geoscience-UPC, 08034, Barcelona, Spain. Electronic address: lucila.candela@upc.edu.
authors.forename: Lucila
authors.initials: L
authors.lastname: Candela
authors.affiliation: Department of Geotechnical Engineering and Geoscience-UPC, 08034, Barcelona, Spain. Electronic address: Karim.Tamoh@upc.edu.
authors.forename: Karim
authors.initials: K
authors.lastname: Tamoh
authors.affiliation: Department of Civil Engineering, University of Alicante, Spain. Electronic address: javier.valdes@ua.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Valdes-Abellan
mesh_terms: D000383:Agriculture / Q000379:methods*; D003105:Colombia; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D060587:Groundwater / Q000737:chemistry*; D031786:Saccharum / Q000254:growth & development*; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical
keywords: Environmental impact; Monitoring; Stillage; Unsaturated zone; Vinasse