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This article in AJ

  1. Vol. 101 No. 6, p. 1363-1371
     
    Received: Dec 12, 2008


    * Corresponding author(s): aheggenstaller@mriresearch.org
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doi:10.2134/agronj2008.0225x

Nitrogen Influences Biomass and Nutrient Partitioning by Perennial, Warm-Season Grasses

  1. Andrew H. Heggenstaller *a,
  2. Kenneth J. Mooreb,
  3. Matt Liebmanb and
  4. Robert P. Anexc
  1. a Midwest Research Institute, 425 Volker Blvd., Kansas City, MO 64110
    b Dep. of Agronomy, Iowa State Univ., Ames, IA 50011
    c Dep. of Agriculture and Biosystems Engineering, NSRIC Buiding, Iowa State Univ., Ames, IA 50011

Abstract

Recent attention has focused on the use of perennial, warm-season grasses as renewable energy crops. The objective of this study was to assess the effects of N fertilization on partitioning of biomass and nutrients between above- and belowground plant components by four warm-season grass species in Iowa. In 2006–2007, established stands of big bluestem (Andropogon geradii Vitman), switchgrass (Panicum virgatum L.), indiangrass [Sorghastrum nutans (L.) Nash], and eastern gamagrass [Tripsacum dactyloides (L.) L.] were fertilized with 0, 65, 140, or 220 kg N ha−1 in the spring and harvested following frost in the fall. Dependent on grass species and year, yield response to N was linear or quadratic. Optimum yield after 2 yr was 13.5 Mg ha−1 at 140 kg N ha−1 for all grasses except eastern gamagrass, which demonstrated lower yield and a consistent linear N response. Nitrogen inputs had pronounced but grass-specific effects on root biomass and nutrient partitioning. For big bluestem and switchgrass, 140 kg N ha−1 maximized root biomass and favored allocation of nutrients to roots over shoots. In contrast, for indiangrass and eastern gamagrass, root biomass and root nutrient allocation were adversely affected by N inputs. For all grasses, 220 kg N ha−1 shifted allocation of nutrients to shoots over roots. Selection of crops and management practices that optimize yield, and maintain a high level of resource partitioning to roots at low to intermediate N input rates will promote the development of productive and efficient bioenergy systems.

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Copyright © 2009. American Society of AgronomyCopyright © 2009 by the American Society of Agronomy