Impact of biosolids on nitrogen use in drought-stressed tall fescue

This study investigates biosolids' impact on nitrogen(N) use in tall fescue(Festuca arundinacea) under same nitrogen level and drought stress conditions. A split-plot design was used with soil moisture regimes ( well-watered and drought stress) as main plots and biosolid treatments as subplots. The biosolids treatments included: 1) control (75 mg/kg N completely provided by NH4 NO3 solution); 2) half-biosolids (37.5 mg/kg N provided by biosolids, and 37.5 mg/kg N provided by NH4NO3 solution); 3) whole-biosolids (75 mg/kg N completely provided by biosolids). Whole-biosolids and half-biosolids improved turfgrass quality, increased clippings and root dry weight of tall fescue under well-watered and drought stress conditions (P 0.05). Biosolids treatments also increased leaf nitrate reductase activity under both soil moisture regimes , and root nitrate reductase under severe drought stress (20% container capacity) (P 0.05). Significant differences in leaf and root TKN as well as N output were observed among biosolids treatments (P 0.05). Our data suggest that biosolids application may improve drought tolerance and promote N use of tall fescue under drought stress.