Plasticity of high and low nutrient-adapted grasses to added sulfur and nitrogen

Crop and native plants can be characterized as high and low nutrient-adapte d based on their expected response to native and applied nutrients. Our obj ective was to compare the plasticity of biomass allocation and tissue nutri ent concentrations to added sulfur (S) and nitrogen (N) across a continuum of high and low nutrient-adapted grasses, represented by barley (Hordeum vu lgare), smooth brome (Bromus inermis), bluebunch wheatgrass (Pseudoroegneri a spicata), and Idaho fescue (Festuca idahoensis). In our greenhouse study, treatments included two S sources (pyrite and gypsum), at 150 and 300 kg S ha(-1), N at 50 kg ha(-1), and a check. Shoot biomass of barley, smooth br ome, and bluebunch wheatgrass was enhanced by S plus N. Shoot biomass of ba rley and smooth brome was greater with pyrite than with gypsum. Root biomas s of smooth brome and bluebunch wheatgrass was greater with pyrite than wit h gypsum. Plant S concentrations of barley and Idaho fescue were enhanced b y added S. Plant S concentrations in barley and smooth brome were greater w ith gypsum than with pyrite. Except for barley, plant S pools (shoot biomas s x shoot S concentration) were enhanced with S plus N compared with no add ed nutrients. Nitrogen pools of barley, smooth brome, and bluebunch wheatgr ass were higher with pyrite than with gypsum. Soil sulfate (SO4) was greate r when S or S plus N was added than without any added nutrients. For barley and smooth brome, soil sulfate tended to be lower with pyrite than with gy psum. For all soils, pH was lower with added S or added S plus N compared w ith unamended soils. While pyrite lowered soil pH, gypsum tended to increas e soil pH. Overall, barley and smooth brome were highly plastic in respondi ng to enhanced nutrient levels, bluebunch wheatgrass was relatively respons ive, and Idaho fescue was least responsive.