Editorial- Valorization of Agroforest Crops for Biomass Utilization
Authors: del Río José C. 
Published: April 2014

There is a growing need to consider alternative agricultural strategies that move an agricultural industry focused on food
production to one that also supplies the needs of other industrial sectors, such as paper, textiles, biofuels or added-value
chemicals, in the context of the so-called lignocellulose biorefinery. Biorefineries use renewable raw materials to produce
energy together with a wide range of everyday commodities in an economic manner. Decreasing our dependency on fossil fuel
reserves and boosting rural development are important goals of modern society. Biorefineries are therefore seen as a very
promising route to meeting our aims for sustained prosperity and preserving the environment. Renewable sources of energy and
products are required for sustainable development of our society in the near future. Plant biomass is the main source of
renewable materials in Earth and represents a potential source of renewable energy and biobased products. Biomass is available
in high amounts at very low cost (as forest, agricultural or industrial lignocellulosic wastes and cultures) and could be a widely
available and inexpensive source for biofuels and bioproducts in the near future.

This special issue of The Open Agriculture Journal is devoted to the “Valorization of agroforest crops for biomass utilization” and provides a comprehensive description of the current state-of-the-art in the whole fields of lignocellulose
biorefineries, including studies on different feedstocks (plant biomass, agro-industrial residues, energy crops or new industrial
crops), technologies for biomass deconstruction and fractionation (i.e. alkaline pulping, organosolv fractionation), and products
(i.e. biofuels, composite building materials, lignin, paper pulp and other industrial products).

Different papers by internationally recognized experts have been collected for this special issue and report various aspects
of biomass utilization and valorization. Among them, the paper by Díaz et al. evaluates different fast-growing species
(paulownia, tagasaste, giant reed, leucaena and sesbania) according to their biomass productivity, chemical composition and the
chemical characteristics of the liquids obtained after an autohydrolysis treatment. The study confirms the feasibility of the nonisothermal
autohydrolysis treatment process for the selected species to yield sugar oligomers and hemicellulosic sugar. The
paper by Marques et al., on the other hand, reported the detailed chemical composition of several non-woody plant fibers (bast
fibers from flax, hemp, kenaf, jute; leaf fibers from sisal, abaca and curaua; and giant reed), which are used as raw materials for
pulp and papermaking, with especial emphasis in the chemistry of lipids and lignin and their fate during alkaline pulping. This
study offers valuable information that will lead to a better industrial utilization of these non-woody plant species of high
socioeconomic interest. Likewise, the paper by Villaverde et al. provided a review of the chemistry of another interesting crop,
Miscanthus x giganteus, as a source of biobased products (i.e. paper pulp) through organosolv fractionation. Organosolv
processes have demonstrated their effectiveness as fractionation treatments, therefore special emphasis was placed by the
authors on these systems and, in particular, in those using carboxylic acids, such as the Acetosolv, Formosolv and Milox
processes. Similarly, the paper by Gullón et al. provided an excellent review of selected process alternatives for biomass
refining. Special attention was devoted to biorefinery schemes dealing with the fractionation of lignocellulosic raw materials by
chemical treatments. The potential of hydrothermal treatments as the first stage of future biorefineries is discussed. Special
attention was also paid to the low-volume, high-added value products that can be solubilized by this type of technology. In the
same way, the paper by da Silva and Curvelo reported the acetone-water delignification of Eucalyptus urograndis, a process
that also fits perfectly with the biomass biorefinery approach, and obtained high selectivity at the beginning of the pulping
process. On the other hand, agricultural residues, which are usually disposed, have major components (cellulose, hemicellulose
and lignin) that can also be exploited for production of bioenergy or bioproducts. In this sense, the paper by Jiménez and
Rodríguez studied the valorization of agricultural residues by fractionation of their components. The authors review the
different possibilities of biomass fractionation by hydrothermal treatments as well as by organosolv delignification.

Alternative and novel uses of biomass products are also reported in this special issue. Although an excellent bio-fuel,
however, new uses of lignin in more high-value-added products might be more attractive and profitable. Thus, the paper by
Gellerstedt et al. focused on the production of carbon fibers from lignin into the wood-based biorefinery concept. Lignin-based
carbon fiber is the most value-added product from a wood-based biorefinery. The replacement of construction steel in cars and
trucks with a much lighter carbon fiber-based composite will ultimately result in more fuel-efficient vehicles. Various attempts
to make carbon fiber from lignins are discussed in this interesting paper. Finally, the paper by Tiilikkala et al. also reports a
novel use of another biomass product, wood pyrolysis liquids (so-called wood vinegar), as biocide and plant protection product.
Wood vinegar and other slow pyrolysis liquids are produced as a by-product of charcoal production. The aim of this review was
to clarify the potential of slow pyrolysis liquids in agricultural use, in particular, in pesticide applications. The main challenges
in developing novel bio control technologies are discussed in this paper and the barriers in the commercialization of biological
control agents are revealed.

In conclusion, all the studies reported in the papers presented in this special issue are intended to get a wider and more
rational use of agro-forest resources as is the cultivated plant biomass used as raw material for the manufacturing of bio-fuels and bio-products in the context of the biorefinery approach. As the Guest Editor of this special issue, I wish to thank all the
contributing authors and reviewers for their efforts to put forth this collection of papers, that I am sure will be of high interest
for the readers of The Open Agriculture Journal.