Influence of reclaimed water irrigation in soil physical properties of urban parks : a case study in Madrid (Spain)

Abstract

Reclaimed water irrigation has been a long-standing practice, especially among water deficit areas such as Spain. This kind of water, more mineralized than drinking water, could imply changes on structural soil features. The main aim of this study was to assess the impact of reclaimed water on aggregate stability, soil penetration resistance, infiltration rate and porosity in soils of one of the urban parks of Madrid. This research was carried out on five successive years (2012?2016) in two urban park plots: one irrigated with reclaimed water (RW) and another one with drinking water (DW). Results showed that irrigation with reclaimed water increased microaggregate stability in the topsoil, probably because of higher values of soil organic matter (SOM). However, macroaggregate stability decreased after RW irrigation in the top and the deepest layer. Soil penetration resistance was significantly higher in the RW plot, probably due to a further development of the root system. Furthermore, a decrease on infiltration rate was observed for RW, apparently because of the influence of sodium. On the other hand, porosity results showed that there was no influence of the kind of irrigation water used. The prolonged use of reclaimed water to irrigate urban parks is potentially leading to a modification of some soil properties, which are key in urban parks soil system. Thus, to avoid future problems, the use of reclaimed water in urban parks irrigation should be continuously monitored.