8
1.2.3 Chemical Composition
Chemical composition determines the nutritional quality of rice straw, which is
important for livestock feed, anaerobic digestion, and as a soil amendment. Rice
straw has low nutritional value and research has been done to improve it. Jenkins
(1998) indicated that the typical components of plant biomass are moisture cellulose, hemicelluloses, lignin, lipids, proteins, simple sugars, starches, water, hydrocarbon, ash, and other compounds. The concentrations of these compounds depend
on the plant species, type of tissue, growth stage, and growing conditions. Rice
straw is considered a lignocellulosic biomass that contains 38% cellulose, 25%
hemicellulose, and 12% lignin (Japan Institute of Energy 2002). Compared to the
biomass of other plants, such as softwood, rice straw is lower in cellulose and lignin
and higher in hemicellulose content (Barmina et al. 2013). Table 1.3 shows the
compositional analysis of rice straw via the work of various researchers.
1.3 Overview of Rice-Straw Management Options
1.3.1 Burning Issues and Alternative Management Options
Intensification of rice-cropping systems has been associated with the use of highyielding and short-duration varieties with shorter turnaround time between crops in
multi-cropping systems. Furthermore, the rapid introduction of combine harvesters
constitutes a game changer because of the larger amounts of straw that are left
spread out on the field. Manual collection of the straw in the field is unprofitable
because of the high labor cost. Incorporation in the soil poses challenges in intensive systems with two to three cropping rounds per year. This is due to the insufficient time for decomposition, leaving the straw with poor fertilization properties for
the soil and hindering crop establishment. As a result, open-field burning of straw
has increased dramatically over the last decade, despite being banned in most ricegrowing countries because of pollution and the associated health issues. Therefore,
it is important to look for sustainable solutions and technologies that can reduce the
environmental footprint and add value by increasing the revenues of rice production
systems. Options for rice-straw management are shown in Fig. 1.4. Rice straw can
inherently be used for soil conditioning thru composting and carbonization; as well
as for bio-energy production and for materials recovery such as silica and bio-fiber
(for industrial use). It is important to note that not all the possible options are
economically viable. This is due to the fact that the processing material and transportation costs in value-adding solutions are still higher as compared to using the
other more traditional options.
N. V. Hung et al.
1.2.3 Chemical Composition
Chemical composition determines the nutritional quality of rice straw, which is
important for livestock feed, anaerobic digestion, and as a soil amendment. Rice
straw has low nutritional value and research has been done to improve it. Jenkins
(1998) indicated that the typical components of plant biomass are moisture cellulose, hemicelluloses, lignin, lipids, proteins, simple sugars, starches, water, hydrocarbon, ash, and other compounds. The concentrations of these compounds depend
on the plant species, type of tissue, growth stage, and growing conditions. Rice
straw is considered a lignocellulosic biomass that contains 38% cellulose, 25%
hemicellulose, and 12% lignin (Japan Institute of Energy 2002). Compared to the
biomass of other plants, such as softwood, rice straw is lower in cellulose and lignin
and higher in hemicellulose content (Barmina et al. 2013). Table 1.3 shows the
compositional analysis of rice straw via the work of various researchers.
1.3 Overview of Rice-Straw Management Options
1.3.1 Burning Issues and Alternative Management Options
Intensification of rice-cropping systems has been associated with the use of highyielding and short-duration varieties with shorter turnaround time between crops in
multi-cropping systems. Furthermore, the rapid introduction of combine harvesters
constitutes a game changer because of the larger amounts of straw that are left
spread out on the field. Manual collection of the straw in the field is unprofitable
because of the high labor cost. Incorporation in the soil poses challenges in intensive systems with two to three cropping rounds per year. This is due to the insufficient time for decomposition, leaving the straw with poor fertilization properties for
the soil and hindering crop establishment. As a result, open-field burning of straw
has increased dramatically over the last decade, despite being banned in most ricegrowing countries because of pollution and the associated health issues. Therefore,
it is important to look for sustainable solutions and technologies that can reduce the
environmental footprint and add value by increasing the revenues of rice production
systems. Options for rice-straw management are shown in Fig. 1.4. Rice straw can
inherently be used for soil conditioning thru composting and carbonization; as well
as for bio-energy production and for materials recovery such as silica and bio-fiber
(for industrial use). It is important to note that not all the possible options are
economically viable. This is due to the fact that the processing material and transportation costs in value-adding solutions are still higher as compared to using the
other more traditional options.
N. V. Hung et al.