Irrigation With Tailored Water: Nitrogen Leachate.

Membrane bioreactors (MBR) can be used as decentralized wastewater treatment systems and may offer the opportunity to adjust for constituents in the effluent based on the end user's requirements. Research at Colorado School of Mines (CSM) revealed that MBR effluent can be adjusted to deliver nitrate (NO₃-N) and ammonium (NH₄-N) concentrations ranging from 0 to 25 mg l^-1 and from 0.5 to 5 mg l^-1, respectively. Studies at CSM and New Mexico State University (NMSU) were initiated to examine the long-term effects of reclaimed water seasonally adjusted for NO₃-N concentrations (tailored effluent qualities) on salt and nitrogen leaching from a turfgrass rootzone and on the quality of warm and cool-season turfgrasses. Both NMSU and CSM test areas include Buffalograss [Buchloe dactyloides (Natt.) Eng.] cv. ‘Legacy' established from sod. Test plots at NMSU also include tall fescue [Festuca arundinacea (Schreb.)] cv. ‘ATF 1258' and ‘Princess 77' bermudagrass [Cynodon dactylon (L.). Test plots at CSM include Kentucky bluegrass [Poa pratensis (L.)]. Both CSM and NMSU, and irrigated utilizing a Toro DL2000 drip system with MBR effluent tailored to retain 15 mg l^-1 NO₃-N. Soils consisted of Bluepoint loamy sand at the NMSU site and Avalon sandy loam at CSM. Irrigation was applied at 120% of reference evapotranspiration (ET₀) for cool-season grasses and at 100% of ET₀ for warm-season grasses. Soil solution access tubes were installed at depths of 0-10 cm, 10-20 cm, and 50-60 cm to collect the leachate. Bare plots with no turf cover were used as controls. Leachate samples were analyzed for electrical conductivity, NO₃-N, NH₄-N, and total P. Analysis of the first year data revealed considerable spatial and temporal variability in salinity and nutrient levels at both locations. Nitrate-N in soil samples and analyte concentrations did not differ between treated and control groups at either NMSU or CSM.