Agriculture is the largest fresh water consuming sector, and maize is the most produced and consumed crop worldwide. The water footprint (WF) methodology quantifies and evaluates the water volumes consumed and polluted by a given crop, as well as its impacts. In this work, we quantified for the first time the green WF (soil water from precipitation that is evapotranspired) and the green virtual water exports of maize from Buenos Aires province, Argentina, during 2016–2017, due to the relevance of this region in the world maize trade. Furthermore, at local level, we quantified the green, blue (evapotranspired irrigation), and grey (volume of water needed to assimilate a pollution load) WF of maize in a pilot basin. The green WF of maize in the province of Buenos Aires ranged between 170 and 730 m3/ton, with the highest values in the south following a pattern of yields. The contribution of this province in terms of green virtual water to the international maize trade reached 2213 hm3/year, allowing some water-scarce nations to ensure water and water-dependent food security and avoid further environmental impacts related to water. At the Napaleofú basin scale, the total WF of rainfed maize was 358 m3/ton (89% green and 11% grey) and 388 m3/ton (58% green, 25% blue, and 17% grey) for the irrigated crop, showing that there is not only a green WF behind the exported maize, but also a Nitrogen-related grey WF.

El indicador de la huella hídrica mide el volumen de agua consumida o contaminada en un proceso productivo y resulta útil para evaluar la sustentabilidad de dicha producción. Este trabajo tiene como objetivo calcular la huella hídrica verde y azul de la leche y el queso elaborados en un tambo-fábrica de Tandil, Argentina. El estudio se realizó en un establecimiento educativo agroindustrial que cuenta con diversos sectores de producción donde los estudiantes realizan sus prácticas formativas. Se analizaron los componentes de la huella hídrica considerando: el agua contenida en el alimento, la bebida animal y el agua de servicios. Los resultados indicaron que el volumen de agua consumido para la elaboración de 1 kg de queso es 10 veces mayor que para 1 kg de leche. La mayor proporción de la huella hídrica la representó el agua verde del alimento. Dentro de la huella azul de la leche, predominó la bebida animal sobre el agua de servicios, mientras que sucedió lo inverso en cuanto a la huella azul del queso. La reutilización del agua de refrescado de la leche para la limpieza del tambo impacta positivamente en la reducción de la huella azul. Se evidencia la necesidad de implementar medidas de reducción de consumos de agua azul, especialmente en la fabricación de quesos. Abstract The water footprint indicator measures the volume of water consumed or polluted during a productive process and it is useful to evaluate the sustainability of the production. This work aims to calculate the green and blue water footprint of milk and cheese made in a dairy farm combined with a cheese factory in Tandil, Argentina. The study was carried out in an educational and agro-industrial institution which has several productive sectors where students develop their training practices. The water footprint components of an animal product were analyzed: water related to feed, drinking water and services water consumption. The results showed that the volume of water consumed to make 1 kg of cheese was 10 times higher than the volume needed to produce 1 kg of milk. The main proportion of the water footprint was given by the green water related to feed. As regard to the blue water footprint of milk, animal drinking water was predominant over services water consumption, while the opposite happened with the blue water of cheese. The reuse of milk cooling water for cleaning the dairy farm positively impacts on blue water reduction. It is necessary to implement measures to reduce the blue water consumption mainly in cheese production.