Switchgrass (Panicum virgatum L.) and Intermediate Wheatgrass (Thinopyrum intermedium) Aboveground and Belowground Growth Response to Nitrogen and Calcium Fertilizer.

The effect of calcium and nitrogen on switchgrass and intermediate wheatgrass growth response was investigated in a greenhouse study.  Switchgrass (cv. ‘Sunburst’ and ‘Dacotah’), and intermediate wheatgrass (cv. ‘Reliant’) were grown in hydroponic sand pots for six months.  A factorial arrangement consisting of three calcium nutrient solution levels (2 mg L^-1, 8 mg L^-1, and 32 mg L^-1) and three nitrogen nutrient solution levels (2 mg L^-1, 8 mg L^-1, and 32 mg L^-1) were applied daily.  Macro nutrients (P, K, Mg, S) and micro nutrients (B, Cu, Fe, Mn, Mo, Zn, Al, Br, I, Co, Li) were maintained at a constant level for the study duration.  Greenhouse temperature was maintained at 29°C/18°C.  Aboveground biomass was harvested eight times for the duration of the study at a clipped height of 15 cm.  Belowground biomass (crown and roots) was harvested at the end the study.   Aboveground and belowground samples were dried at 60°C until a constant temperature was reached and ground to pass a 1 mm screen.  Cation and anion elements were analyzed using an ion chromatograph. Intermediate wheatgrass aboveground and belowground biomass followed a positive, polynomial response to increasing N and Ca treatments.  High calcium rates (32 mg L^-1) decreased switchgrass aboveground biomass under medium (8 mg L^-1) to high nitrogen (32 mg L^-1) treatments.  Calcium concentrations in aboveground samples were higher for switchgrass than intermediate wheatgrass.  Sulfur and magnesium concentrations in aboveground samples were higher for intermediate wheatgrass than switchgrass regardless of N or Ca treatments.  Phosphorous and potassium concentrations increased for switchgrass and intermediate wheatgrass with higher N concentrations with intermediate wheatgrass having higher P and K concentrations than switchgrass.  Overall, aboveground biomass response to Ca was positive for intermediate wheatgrass but resulted in lower yields for switchgrass.