Soil Analysis Before and 5 Years After Effluent Water Irrigation.

The issues surrounding effluent water irrigation are complex.  Soil samples were collected and analyzed at and 5 years after the initiation of effluent water irrigation at 12 parks and golf courses.   Soil salinity (as gauged by soil electrical conductivity) and soil organic matter content did not increase at most of the sample sites over the five-year period.  On average there was a slight increase in soil pH.  The average soil exchangeable sodium percentage increased from 2.65% to 5.35% during the 5 years.  Likewise sodium adsorption ratio (SAR) increased from 2.89 to 5.32.   Results suggested sodicity is of greater concern than salinity at most of the testing sites, since soil ESP and SAR are two parameters that exhibited the most significant changes.  Nitrate–N content deceased significantly with soil depth.   Nitrate-N level beyond the turfgrass rootzone samples was < 3 mg kg^-1.  This indicates that nitrate contamination of groundwater should not be a great concern when using recycled water for the irrigation of turf systems. Dense, well-managed, and active-growing turfgrasses serve as bio-filtration systems for removal of excess nitrate.