TITLE:
Cultivation of Erianthus and Napier Grass at an Abandoned Mine in Lampung, Indonesia
AUTHORS:
Nobuhito Sekiya, Jun Abe, Fumitaka Shiotsu, Shigenori Morita
KEYWORDS:
Biomass, Cellulosic Energy Crops, Unused Land, Subsurface Soils
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.11,
May
23,
2014
ABSTRACT: The production of
cellulosic bioethanol from non-edible plants is drawing increasing attention,
as it potentially avoids food-fuel competition. Because growing such plants on
farmland indirectly reduces food availability, the plants should be grown on
marginal, non-arable lands. In this study, we evaluated the growth of cellulosic
energy crops at a former mining site in Indonesia. This mine was abandoned
because it contained few mineral deposits, and exposed subsoils rather than toxic
soils prevented revegetation. In the first trial, growths of two energy plant
species Erianthus spp. and Napier
grass (Pennisetum purpureum) were
compared with that of maize (Zea mays)
at the mine site and a nearby degraded farm. Erianthus and Napier grass produced 11.7 and 22.5 t·ha-1 of shoot dry matter at 8 months after planting (MAP) in the farm respectively while
maize plants failed to establish, but none of the three species grew at the
mine. In the second trial, two-week-old seedlings of Erianthus and Napier grass rather than stem cuttings as used in the
first trial were planted at the mine site. Erianthus and Napier grass produced 16.3 and 24.0 t·ha-1 of shoot dry matter
over the course of 18 months, respectively. Application of organic fertilizer
significantly increased shoot dry matter to 18.9 and 39.6 t·ha-1 in Erianthus and Napier grass, respectively.
During the 18-month growth period, both of the energy plants significantly
increased soil carbon at the 0 - 0.3 m depth from 0.33% to 1.15% - 1.23% when
chemical fertilizer was applied and to 0.67% - 0.69% when both chemical and
organic fertilizers were applied. From 0 - 5 MAP, soil surface level dropped by
28.0 - 34.7 mm in plots without plants due to soil erosion. In contrast, both
of the energy plants significantly reduced the drop of soil surface level to
16.0 - 19.3 mm in plots with chemical fertilizer alone and to 18.0 - 20.7 mm in
plots with chemical and organic fertilizers. Proportions of small soil
particles, that would be easily detached and transported by water flow compared
with large particles, were larger in the planted plots than the no-plant plots
at 16 MAP. The results suggest that successful cultivation of energy plants on
abandoned mine sites is possible, particularly if seedlings are transplanted
and the crops are fertilized with organic fertilizer. In addition, the
cultivation of Erianthus and Napier
grass has positive impacts on soil quality that may contribute to their
sustainability as crops and to the conservation of the local ecosystem.