Bermudagrass Growth in Soil Contaminated with Hydraulic Fracturing Drilling Fluid

Hydraulic fracturing is the process of injecting aqueous solutions at high pressure to break apart rock formations and increase the efficiency of natural gas extraction. The solutions are recovered and have been land-applied as one disposal technique. Excessive fluid application can result in increased soil salinity that can inhibit or prevent plant growth. The objective of this greenhouse study was to evaluate the effects of inorganic fertilizer, broiler litter, and Milorganite® and soil depth interval (0-15 cm or 0-30 cm) on the growth of bermudagrass [Cynodon dactylon (L.) Pers] in soil that was collected from a site that had been contaminated with fracturing fluid and initially devoid of vegetation. Amendment rates were added to provide 60 mg of plant available N/kg. In soil from the 0-15 cm depth, electrical conductivity (ECe), Na, and Cl levels were 14.5 dS/m, 2994 mg/kg, and 5603 mg/kg, respectively. For the 0-30 cm depth, ECe, Na, and Cl levels were 14.1 dS/m, 2550 mg/kg, and 5020 mg/kg, respectively. Bermudagrass was sprigged and harvested after nine weeks and shoot, root, and total biomass determined. Addition of inorganic fertilizer, broiler litter, or Milorganite® resulted in greater shoot biomass compared to unamended soil. Soil depth interval did not affect shoot biomass production, but the plants grown in 0-30-cm-depth soil had greater root biomass, length, volume, and surface area compared to those grown in soil from the 0-15 cm depth. At harvest, total inorganic soil N concentrations in the amended bermudagrass treatments were approximately 50 mg/kg less than the amended non-vegetative treatments. The addition of recommended plant nutrients enhanced bermudagrass growth. Mixing of the surface-applied hydraulic fracturing fluid with the subsurface soil resulted in a dilution effect that decreased detrimental soil salinity levels.