Livestock producers in Montana utilize irrigated annual barley hay for winter feed. Increased production of coalbed methane (CBM) wells could potentially provide an additional water source which could be used for irrigation. The objectives of this research are to evaluate the effects of CBM water on forage yield and quality in relation to livestock requirements. Fourteen barley cultivars were irrigated with CBM water and well water (WW). Sample clippings were taken at three dates (early, mid, harvest) and analyzed for forage quality (dry matter, crude protein, fiber, and nitrate concentrations). Harvest yields were lower in CBM forages than WW (3.26 tons DM/A vs. 3.82 tons DM/A, respectively). Forage accumulation of toxic levels of nitrate has been a significant problem in recent years. Interestingly, nitrate-N levels were much lower in CBM-irrigated (0.04) vs. WW-irrigated forages (0.41 percent). Fiber concentrations (acid detergent and neutral detergent fiber) were significantly poorer (higher levels) at the harvest stage in WW vs. CBM-irrigated forages. Forage crude protein levels declined significantly 7.8 (CBM) vs. 14.3 percent (WW). In this preliminary study, nitrate and fiber levels were lower in CBM forages, however use of CBM water limited forage productivity and protein content. Continued testing will evaluate the long term effects of CBM irrigation on barley forage.

*altodd@montana.edu