Prayogo, Cahyo (2013) Carbon storage and sequestration under different land uses with a focus on biomass crops. PhD thesis, University of Warwick.

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Abstract

Climate change is caused by rising quantities of greenhouse gases,
particularly CO2, in the atmosphere, largely through consumption of fossil fuels.
There is interest in sustainable energy generation from renewable resources,
particularly biomass crops to reduce reliance on fossil fuels. A key advantage of
such energy systems is that they assimilate atmospheric CO2 and thus help
mitigate climate change. Soil represents one of the largest pools of C in the
biosphere and there is potential to use soil as a sink to sequester C to mitigate
climate change. The aim of this project was to investigate soil C storage and
sequestration in short rotation coppice (SRC), which is one of the major biomass
cropping systems in temperate climates. 14 year old plantations of willow and
poplar established at Rothamsted Research in Harpenden were used to investigate
how the quantity and quality of organic matter under the SRC compare to that
under adjacent land uses, including arable cropping, set-aside grassland and
natural woodland. It was shown that change in land use to SRC led to increased C
storage in soil relative to alternative agricultural systems, while conversion to setaside
had no effect on soil C stocks. There was no difference in C storage under
different poplar or willow cultivars. Differences in C storage between arable, SRC
and set-aside plots reflected changes in C stocks at 0-30 cm depth with no change
occurring to C at 30-60 cm. The quality of C was investigated by analysis of the
light fraction organic matter pool which acts as an early indicator of long term
changes in total soil organic matter. The work showed that the free LFOM pool
responded to land use change while the physically protected intra-aggregate
LFOM pool did not. While changes to amounts of LFOM following land use
change occurred in soil at 0-30 cm depth, there were no changes at 30-60 cm
depth. Fourier Transform Infra Red spectroscopy showed that the chemical
composition of free and intra aggregate LFOM was different, and that
composition of both pools was affected by land use. Fourier Transform Ion
Cyclotron Resonance Mass spectroscopy was shown to provide fine level
resolution of the composition of soluble organic matter, and demonstrated that the
aromaticity and chain length of C was higher in woodland than arable soil. The
potential to sequester C in soil as biochar is a promising option to promote longterm
sequestration of C in soil. The potential to use a fluidised bed reactor to
produce biochar was investigated. Life Cycle Analysis showed that 4700C was the
optimal temperature to promote retention of C in biochar during pyrolysis, while
minimising losses of C as bio-oil and gases. Addition of steam during pyrolysis
was shown to increase the surface area of the resulting biochar. Addition of
biochar to soil reduced net C mineralisation of soil organic matter and litter at a
rate of 2 % w/w, but not at 0.5 % w/w. However both concentrations of biochar
affected net mineralisation of N. Phospholipid fatty acid analysis showed that both
concentrations of biochar altered microbial community structure, with fungal
biomass in particular promoted by the addition of biochar. Overall the work
demonstrates that SRC promotes significant storage of C within soil organic
matter, which has implications for the overall energy budget of SRC biomass.
Furthermore, conversion of biomass to biochar for land application provides
opportunities for sequestration of C within soil. Application of biochar to soil
would provide further benefits to the overall energy balance of SRC by reducing
mineralisation rates of native soil organic matter and litter.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QH Natural history > QH301 Biology S Agriculture > SD Forestry
Library of Congress Subject Headings (LCSH):	Carbon sequestration, Carbon dioxide -- Environmental aspects, Energy crops, Soils -- Carbon content, Carbon cycle (Biogeochemistry)
Official Date:	May 2013
Dates:	Date Event May 2013 Submitted
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bending, G. D. (Gary D.)
Sponsors:	University of Warwick
Extent:	xix, 334 leaves : illustrations.
Language:	eng

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