Reclaimed Wastewater to Irrigate Olive Groves and Vineyards: Effects on Soil Properties

Having drinking water is one of the sustainable development goals (SDG no. 6) that is not always easy to ensure, especially in countries like Spain or arid regions marked by water deficit. The reuse of treated water should be considered when planning water resources, but it is necessary to verify that this effectiveness is applicable to real situations. A field trial was carried out in several study areas distributed in agricultural parcels of south east Spain. Soils from two olive groves and two vineyards irrigated with treated wastewater (TW) were monitored for to compare with other plantations irrigated with conventional well water (WW) since July 2016–September 2018. Five different irrigation water sources were analyzed (two from well water and three from reclaimed wastewater). No microbiological, metal content, toxicity or organic compounds (PAHs and PCBs) in the studied water samples were detected and reclaimed municipal wastewater was comparable in quality to the conventional sources at all the demonstration sites, except for higher electrical conductivity. Soils irrigated with TW had higher values for electrical conductivity, N, K, Na, Mg, Mn and cation exchange capacity. The main precautions to be considered when irrigating with treated wastewater are its salt content and its tendency to high values of electrical conductivity. Otherwise, they are an interesting contribution of nutrients to soil. Hence adopting this water type to irrigate orchards, vineyards and olive groves could help to save primary water resources.