skip to main content


Title: Belowground impacts of perennial grass cultivation for sustainable biofuel feedstock production in the tropics

Perennial grasses can sequester soil organic carbon (SOC) in sustainably managed biofuel systems, directly mitigating atmospheric CO 2 concentrations while simultaneously generating biomass for renewable energy. Our objective was to quantify SOC accumulation and identify the primary drivers of belowground C dynamics in a zero-tillage production system of tropical perennial C4 grasses grown for biofuel feedstock in Hawaii. Specifically, the quantity, quality, and fate of soil C inputs were determined for eight grass accessions – four varieties each of napier grass and guinea grass. Carbon fluxes (soil CO 2 efflux, aboveground net primary productivity, litterfall, total belowground carbon flux, root decay constant), C pools (SOC pool and root biomass), and C quality (root chemistry, C and nitrogen concentrations, and ratios) were measured through three harvest cycles following conversion of a fallow field to cultivated perennial grasses. A wide range of SOC accumulation occurred, with both significant species and accession effects. Aboveground biomass yield was greater, and root lignin concentration was lower for napier grass than guinea grass. Structural equation modeling revealed that root lignin concentration was the most important driver of SOC pool: varieties with low root lignin concentration, which was significantly related to rapid root decomposition, accumulated the greatestmore » amount of SOC. Roots with low lignin concentration decomposed rapidly, but the residue and associated microbial biomass/by-products accumulated as SOC. In general, napier grass was better suited for promoting soil C sequestration in this system. Further, high-yielding varieties with low root lignin concentration provided the greatest climate change mitigation potential in a ratoon system. By understanding the factors affecting SOC accumulation and the net greenhouse gas trade-offs within a biofuel production system will aid in crop selection to meet multiple goals toward environmental and economic sustainability.« less
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [2] ;  [2]
  1. Univ. of Hawaii, Honolulu, HI (United States). Dept. of Natural Resources and Environmental Management
  2. Univ. of Hawaii, Honolulu, HI (United States). Dept. of Tropical Plant and Soil Sciences
  3. Univ. of Hawaii, Honolulu, HI (United States). Dept. of Biology
Publication Date:
Grant/Contract Number:
Published Article
Journal Name:
Global Change Biology. Bioenergy
Additional Journal Information:
Journal Volume: 9; Journal Issue: 4; Journal ID: ISSN 1757-1693
Research Org:
Univ. of Hawaii, Honolulu, HI (United States)
Sponsoring Org:
Country of Publication:
United States
09 BIOMASS FUELS; carbon sequestration; guinea grass; napier grass; root decomposition; soil carbon; structural equation modeling; total belowground carbon flux
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1346276; OSTI ID: 1393470