Author
K. C. Kwon
Other affiliations: Auburn University
Bio: K. C. Kwon is an academic researcher from Tuskegee University. The author has contributed to research in topics: Coal & Viscometer. The author has an hindex of 8, co-authored 22 publications receiving 2441 citations. Previous affiliations of K. C. Kwon include Auburn University.
Topics: Coal, Viscometer, Hydrogen, Viscosity, Catalysis
Papers
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TL;DR: In this article, the essential elements of what is known about soil organic matter dynamics that may result in enhanced soil carbon sequestration with changes in land-use and soil management are discussed.
Abstract: SUMMARY When agricultural land is no longer used for cultivation and allowed to revert to natural vegetation or replanted to perennial vegetation, soil organic carbon can accumulate by processes that essentially reverse some of the effects responsible for soil organic carbon losses from when the land was converted from perennial vegetation. We discuss the essential elements of what is known about soil organic matter dynamics that may result in enhanced soil carbon sequestration with changes in land-use and soil management. We review literature that reports changes in soil organic carbon after changes in land-use that favor carbon accumulation. This data summary provides a guide to approximate rates of SOC sequestration that are possible with management, and indicates the relative importance of some factors that influence the rates of organic carbon sequestration in soil. There is a large amount of variation in rates and the length of time that carbon may accumulate in soil that are related to the productivity of the recovering vegetation, physical and biological conditions in the soil, and the past history of soil organic carbon inputs and physical disturbance. Maximum rates of C accumulation during the early aggrading stage of perennial vegetation growth, while substantial, are usually much less than 100 g C m y . Average rates of accumulation are similar for forest or grassland establishment: 33.8 g C m y and 33.2 g C m y respectively. These observed rates of soil organic C accumulation, when combined with the small amount of land area involved, are insufficient to account for a significant fraction of the missing C in the global carbon cycle as accumulating in the soils of formerly agricultural land.
2,419 citations
TL;DR: In this paper, a method of removing oxygen from liquid biomass to produce petroleum-comparative liquid hydrocarbons with hydrogen and a catalyst was developed, which was evaluated with a GC/MS analyzer for liquid reaction products and another GC for gaseous reaction products.
98 citations
TL;DR: In this article, a series of 23 model donor solvents was used to rank their efficacy for the dissolution of Western Kentucky No. 9 14 coal, as measured by coal conversion, at three levels of available hydrogen.
25 citations
TL;DR: Pyrite catalyzes the hydrogenation of the N-containing ring in quinoline (Q) to form the active H-donor, 1,2,3,4-tetrahydroquinoline (THQ), which is shown to dissolve coal readily at 325 °C, a temperature lower than that commonly used in most liquefaction processes as mentioned in this paper.
22 citations
TL;DR: In this paper, a novel open-tube evaporation method was developed to determine the experimental diffusion coefficients of the vapors of various liquids diffused into air, where no fresh air was passed over the top end of the diffusion path by forced convection.
22 citations
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TL;DR: In this article, the influence of land use changes on soil carbon stocks was reviewed and a meta-analysis of these data from 74 publications was conducted, which indicated that soil C stocks decline after land use change from pasture to plantation (−10%), native forest to plantations (−13), native forests to crop (−42), and pasture to crop (+59%), while the reverse process usually increased soil carbon and vice versa.
Abstract: The effects of land use change on soil carbon stocks are of concern in the context of international policy agendas on greenhouse gas emissions mitigation. This paper reviews the literature for the influence of land use changes on soil C stocks and reports the results of a meta analysis of these data from 74 publications. The meta analysis indicates that soil C stocks decline after land use changes from pasture to plantation (−10%), native forest to plantation (−13%), native forest to crop (−42%), and pasture to crop (−59%). Soil C stocks increase after land use changes from native forest to pasture (+ 8%), crop to pasture (+ 19%), crop to plantation (+ 18%), and crop to secondary forest (+ 53%). Wherever one of the land use changes decreased soil C, the reverse process usually increased soil carbon and vice versa. As the quantity of available data is not large and the methodologies used are diverse, the conclusions drawn must be regarded as working hypotheses from which to design future targeted investigations that broaden the database. Within some land use changes there were, however, sufficient examples to explore the role of other factors contributing to the above conclusions. One outcome of the meta analysis, especially worthy of further investigation in the context of carbon sink strategies for greenhouse gas mitigation, is that broadleaf tree plantations placed onto prior native forest or pastures did not affect soil C stocks whereas pine plantations reduced soil C stocks by 12–15%.
3,039 citations
TL;DR: In this article, the authors proposed a sustainable management of soil organic carbon (SOC) pool through conservation tillage with cover crops and crop residue mulch, nutrient cycling including the use of compost and manure, and other management practices.
2,931 citations
TL;DR: The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is pro- posed as a novel approach to establish a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems.
Abstract: The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is pro- posed as a novel approach to establish a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. Apart from positive effects in both reducing emissions and increasing the sequestration of greenhouse gases, the production of bio-char and its application to soil will deliver im- mediate benefits through improved soil fertility and increased crop production. Conversion of biomass C to bio-char C leads to sequestration of about 50% of the initial C compared to the low amounts retained after burning (3%) and biological decomposition (<10-20% after 5-10 years), therefore yielding more stable soil C than burning or direct land application of biomass. This efficiency of C conversion of biomass to bio-char is highly dependent on the type of feedstock, but is not significantly affected by the pyrolysis temperature (within 350-500 ◦ C common for pyrolysis). Existing slash-and- burn systems cause significant degradation of soil and release of greenhouse gases and opportunies may exist to enhance this system by conversion to slash-and-char systems. Our global analysis revealed that up to 12% of the total anthropogenic C emissions by land use change (0.21 Pg C) can be off-set annually in soil, if slash-and-burn is replaced by slash-and-char. Agricultural and forestry wastes such as forest residues, mill residues, field crop residues, or urban wastes add a conservatively estimated 0.16 Pg C yr −1 . Biofuel production using modern biomass can produce a bio-char by-product through pyrolysis which results in 30.6 kg C sequestration for each GJ of energy produced. Using published projections of the use of renewable fuels in the year 2100, bio-char sequestration could amount to 5.5-9.5 Pg C yr −1 if this demand for energy was met through pyrolysis, which would exceed current emissions from fossil fuels (5.4 Pg C yr −1 ). Bio-char soil management systems can deliver tradable C emissions reduction, and C sequestered is easily accountable, and verifiable.
2,553 citations
TL;DR: In this article, the authors quantify potential soil organic carbon sequestration rates for different crops in response to decreasing tillage intensity or enhancing rotation complexity, and to estimate the duration of time over which sequestration may occur.
Abstract: Changes in agricultural management can potentially increase the accumulation rate of soil organic C (SOC), thereby sequestering CO 2 from the atmosphere. This study was conducted to quantify potential soil C sequestration rates for different crops in response to decreasing tillage intensity or enhancing rotation complexity, and to estimate the duration of time over which sequestration may occur. Analyses of C sequestration rates were completed using a global database of 67 long-term agricultural experiments, consisting of 276 paired treatments. Results indicate, on average, that a change from conventional tillage (CT) to no-till (NT) can sequester 57 ± 14 g C m -2 yr -1 , excluding wheat (Triticum aestivum L.)-fallow systems which may not result in SOC accumulation with a change from CT to NT. Enhancing rotation complexity can sequester an average 20 ± 12 g C m -2 yr -1 , excluding a change from continuous corn (Zea mays L.) to corn-soybean (Glycine max L.) which may not result in a significant accumulation of SOC. Carbon sequestration rates, with a change from CT to NT, can be expected to peak in 5 to 10 yr with SOC reaching a new equilibrium in 15 to 20 yr. Following initiation of an enhancement in rotation complexity, SOC may reach a new equilibrium in approximately 40 to 60 yr. Carbon sequestration rates, estimated for a number of individual crops and crop rotations in this study, can be used in spatial modeling analyses to more accurately predict regional, national, and global C sequestration potentials.
2,097 citations