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Nitrogen Influences Biomass and Nutrient Partitioning by Perennial, Warm‐Season Grasses
Author(s) -
Heggenstaller Andrew H.,
Moore Kenneth J.,
Liebman Matt,
Anex Robert P.
Publication year - 2009
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2008.0225x
Subject(s) - panicum virgatum , agronomy , perennial plant , nutrient , biomass (ecology) , panicum , biomass partitioning , growing season , andropogon , biology , bioenergy , environmental science , biofuel , ecology
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.