Assessment on micronutrient concentration after reclaimed water irrigation: A CASE study in green areas of Madrid*

Abstract

AbstractThe use of reclaimed water to cope with water scarcity has become one of the main alternative resources in water‐deficit countries. Reclaimed water represents a significant component in integrated water resources management in the city of Madrid (Spain). Madrid City Council replaced the usual drinking water irrigation system by a reclaimed water one. This study assessed the effects of reclaimed water irrigation on micronutrient concentration (B, Cu, Fe, Mn and Zn) in the soil–plant system of two urban green areas in Madrid. Results showed that reclaimed water used in Madrid was adequate for irrigation regarding the studied micronutrients. Nevertheless, micronutrient concentration were slightly higher in reclaimed water than in drinking water. Soil organic matter (SOM) and pH had strong influence in some of the micronutrient concentrations in soils and in its bioavailability and transference to cedars (SOM ↔ B Soil, Cu Soil, Fe Soil; pH ↔ B Soil, Fe Soil, Mn Soil). There was no significant correlation between micronutrient concentration in irrigation water and in cedar leaves. Thus, foliar concentration of the studied micronutrients did not exceed toxic limits, even after 15 years of reclaimed water irrigation. Moreover, despite one park was irrigated with reclaimed water 10 years more than the other, reclaimed water irrigation plots did not show major differences in micronutrient concentration between the two parks.