Above- and Belowground Prairie Cordgrass Response to Applied Nitrogen on Marginal Land

Prairie cordgrass (Spartina pectinata, Link.) has been evaluated for its biomass potential because of its high yield, relatively low nutrient demand, and diverse geographical adaptation. Our objectives were to determine (1) biomass production potential of prairie cordgrass in South Dakota and Kansas under varying nitrogen levels, (2) the effect of N on prairie cordgrass yield components (tillers m⁻² and tiller mass), and (3) the effect of N on yield and N concentration of belowground biomass. Older stands of Red River prairie cordgrass (RR-PCG) in South Dakota and Atkins prairie cordgrass (AT-PCG) in Kansas were fertilized with 0, 56, 112 and 168 kg N ha⁻¹ from 2008 to 2011 in South Dakota and in 2009 and 2010 in Kansas. Experimental design at all locations was a 4 × 4 Latin square. Prairie cordgrass was harvested around a killing frost in October and early November. Biomass production ranged from 5.50 to 13.69 Mg ha⁻¹ in South Dakota and 5.33 to 12.51 Mg ha⁻¹ in Kansas. Prairie cordgrass yield did not increase significantly with N application at any location or year. Across years, tiller density ranged from 536 to 934 tillers m⁻² for RR-PCG in South Dakota and from 234 to 315 tillers m⁻² for AT-PCG in Kansas. Neither tiller density or tiller mass was affected by N rate at any location in any year. Belowground biomass production to a depth of 25 cm was equal to or greater than aboveground biomass. However, it was not affected by N rate in all locations by any year. Understanding prairie cordgrass nitrogen-use dynamics to improve biomass and nutrient management will be essential for future investigations. Findings of this study are important to support the notion that prairie cordgrass biomass production in two different environments can be achieved with minimal N inputs.