Nitrate Leaching From Turfgrasses Irrigated with Tailored Effluent Water Using Subsurface Drip System.

Membrane bioreactors (MBR) can be used as decentralized water 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 content (tailored water) on salt and nitrogen leaching from a turfgrass rootzone and on the quality of warm and cool-season turfgrasses. Buffalograss [Buchloe dactyloides (Natt.) Eng.] cv. ‘Legacy’ and Kentucky bluegrass [Poa pratensis (L.)] Colorado Blue^TM blend were established from sod at CSM. Test plots at NMSU include tall fescue [Festuca arundinacea (Schreb.)] cv. ‘Pennington ATF1258’, ‘Legacy’ buffalograss, and ‘Princess 77’ bermudagrass [Cynodon dactylon (L.)]. Both test areas are irrigated from a Toro DL2000 drip system with treated effluent water containing 15 mg l^-1 of NO₃-N. Control plots are irrigated with potable water and will receive equivalent amounts of granular nitrogen fertilizer to the total N applied to plots irrigated with treated effluent. Soils consist of Bluepoint loamy sand at the NMSU site and Avalon sandy loam at CSM. Irrigation is applied at 100% of reference evapotranspiration (ET₀). Soil solution access tubes are installed at depths of 0-10 cm, 10-20 cm, and 50-60 cm to collect the leachate. Bare plots with no turf cover are used as controls. Turf coverage and turf quality will be assessed bi-weekly. Leachate samples will be analyzed monthly for electrical conductivity, NO₃-N, NH₄-N and total P.