Impact of reclaimed water irrigation on soil health in urban green areas

• Reclaimed water irrigation improved soil nutrient conditions.
• Salinity increasing but no salinization occurred under reclaimed water irrigation.
• Difference of soil heavy metals contents under reclaimed and tap water irrigation is insignificant.
• Reclaimed water irrigation improved significantly soil microorganism activities.

Rapid increase of reclaimed water irrigation in urban green areas requires investigating its impact on soil health conditions. In this research, field study was conducted in 7 parks in Beijing with different histories of reclaimed water irrigation. Twenty soil attributes were analyzed to evaluate the effects of reclaimed water irrigation on the soil health conditions. Results showed that soil nutrient conditions were ameliorated by reclaimed water irrigation, as indicated by the increase of soil organic matter content (SOM), total nitrogen (TN), and available phosphorus (AP). No soil salinization but a slight soil alkalization was observed under reclaimed water irrigation. Accumulation of heavy metals in soil was insignificant. It was also observed that reclaimed water irrigation could significantly improve the soil microorganism activities. Overall, the soil health conditions were improved with reclaimed water irrigation, and the improvement increased when the reclaimed water irrigation period became longer.