KENAF BOOKLET

Prepared in the framework of the BIOKENAF project

QLK5 CT2001 01729

Prepared by:

CRES UNICT UTH CETA BTG INIA UniNOVA UNIBO NAGREF A&F INRA ADAS KENAF BOOKLET

BIOKENAF CONSORTIUM

Partners Country Contact details CRES Greece Dr. Efi Alexopoulou ( [email protected] ) Center for Renewable Tel: +30 210 66030382, Fax: +30 210 6603301 Energy Sources Biomass Department Web-site: www.cres.gr (Coordinator) UNICT Italy Prof. Salvatore Luciano Cosentino University of Catania ([email protected]) Department of Agronomy Tel.: +39 095 23411, Fax: +39 095 234449 and Animal Production (DACPA) Web-site: www.unict.it UTH Greece Prof. Nikos Danalatos ( [email protected] ) University of Thessaly Tel.: +30 421 74000, Fax: +30 421 74270 Department of Crop Production Web-site: www.uth.gr BTG The Netherlands Dr. Douwe van den Berg Biomass Technology ([email protected] ) Group B V Tel.: +31 53 4862288, Fax: +31 53 4893116 Web-page: www.btgworld.com CETA Italy Dr. Massimo Veccheit Centre for Theoretical ([email protected] ) and Applied Ecology Tel: +39 040 3755610, Fax: +39 0481 599268 Web-page: www.ceta.go.it , www.technoline.area.trieste.it INIA Spain Dr. Jose Luis Tenorio ( [email protected] ) Instituto Nacional de Tel: +34 91 8892943, Fax: +34 91 8828124 Investigacion y Technologia Agraria y Web-page: www.inia.es Alimentaria UniNOVA Portugal Dr. Ana Luisa Fernando ( [email protected] ) University of Lisbon Tel: +351 21 2948563, Tel and Fax: +351 21 2948543 Grupo de Disciplinas de Ecologia da Hidrosfera Web-site: http://campus.fct.unl.pt NAGREF Greece Dr. Evripidis Kipriotis ( [email protected] ) Komotini Agricultural Tel: +30 2531 0 81920, Fax: +30 531 0 33556 Research Station Web-site: www.nagref.gr A&F The Netherlands Dr. Steef Lips ( [email protected] ) Agrotechnology & Food Tel: +31 317 475 391, Fax: +31 317 475 347 Sciences Group Web-page: www.afsg.wur.nl UNIBO Italy Prof. Gianpetro Venturi ( [email protected] ) University of Bologna Tel.: +39 051 2096652 Department of Agro environmental Science Fax: +39 051 2096242, - 2096241 and Technologies (DiSTA) Web-page: www.unibo.it INRA France Dr. Ghislain Gosse ( [email protected] ) Institut Nacional de Tel.: +33 03 22 85 75 04 , Fax: +33 03 22 85 69 96 Researche Agronomique Web-page: www.inra.fr ADAS UK Ltd UK Dr. Sarah Cook ( [email protected] ) Tel: +44 1354 697 203, Fax: +44 1354 694 488 Web-page: www.adas.co.uk

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PREFACE

BIOKENAF project had as overall objective to introduce and evaluate kenaf as a non-food crop through an integrated approach for alternative land use in South EU that will provide diversified opportunities for farmers and biological materials for the “bio-based industries” of the future. The main research topics were the followings:
To determine the sustainable yielding potential of kenaf , as a non- food crop at different locations in Southern Europe, namely Greece, Italy, France, Spain and Portugal and to assess the limitations that cultivating techniques, such are: irrigation, nitrogen, sowing date and plant density place on crop growth and productivity.
To develop a dynamic crop growth simulation model for kenaf that will be a very useful tool for yield predictions.
To evaluate the effect of harvesting time and storage methods to the quantity and quality of the harvested material for industrial and energy applications.
To evaluate the suitability of kenaf for both selected industrial (high added value) and thermochemical energy applications (combustion, gasification and pyrolysis).
To carry out environmental assessment and LCA that will contribute to make scenarios for alternative land use in the agricultural regions of south EU.
To conduct an economic evaluation of the crop for alternative land use in selected agricultural systems of southern EU regions.

In the light of this project ( http://www.cres.gr/biokenaf ) this BOOKLET for KENAF was prepared. The information provided in this booklet has been organished in six chapters. The booklet starts ( chapter 1 ) with a short description of the crop (origin, botanical description, important of the crop and area of cultivation). In chapter 2 the eco physiological requirements of the crop described. The management of the crop (sowing dates, plant densities, nitrogen and irrigation requirements and finally the weed management) is presented in chapter 3 based on the international literature as well as on the data that was collected in the framework of this project. In chapter 4 the reported yields worldwide were recorded with special emphasis on the type of the cultivated variety (early or late) and on the new released varieties. Kenaf it is characterised as a multi purpose crop due to its high number of final end uses that presented in chapter 5 . The main findings of the BIOKENAF research topics outlined in chapter 6 covering the whole production chain (production-harvesting-storage-end use) through an economic and environmental approach.

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CONTENTS 1. Short description of Kenaf 1 1.1 Taxonomy and origin 1 1.2 Botanical description of the crop 1 1.2.1 Stems 1 1.2.2 Leaves 2 1.2.3 Flowers and capsules 2 1.2.4 Root 4 1.3 Importance of the crop and state of the art on kenaf 5 research in Europe and worldwide 1.4 Area of cultivation and world production 6 2. Eco physiological requirements 8 3. Management of the crop 10 3.1 Sowing dates and plant densities 10 3.2 Nitrogen requirements 12 3.3 Irrigation requirements 13 3.4 Weed management 14 4. Biomass yields and varieties 16 4.1 Early maturity varieties 16 4.2 Late maturity varieties 18 4.3 New released varieties 19 5. Uses of the crop 20 6. Main results on the research topics that dealt in the 24 BIOKENAF project 6.1 Yields of kenaf in South Europe 24 6.1.1 Effect of sowing date 24 6.1.2 Effect of plant density 25 6.1.3 Effect of irrigation rate 26 6.1.4 Effect of nitrogen rate 27 6.1.5 Effect of variety 28 6.2 Development of a growth simulation model 29 6.3 Harvest and storage trials 31 6.4 Suitability of kenaf for selected industrial applications 33 6.5 Thermochemical kenaf applications 35 6.6 Environmental analysis and LCA 35 6.7 Economics analysis of the crop 36 References 37

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1. Short description of the crop

1.1 Taxonomy and origin Kenaf ( Hibiscus cannabinus L.) is a short-day annual herbaceous plant mainly cultivated for the soft bast fiber in its stem (Dempsey, 1975). It belongs to the Malvaceae, a family notable for both its economic and horticulture importance. The genus of Hibiscus is widespread, including some 200 annual and perennial species. Kenaf is closely related to cotton, okra, and hollyhocks. Kenaf, along with roselle, is classified taxonomically in the Furcaria section of Hibiscus . This section includes from 40 to 50 species that were described throughout the tropics and they are closely related morphologically (Dempsey, 1975). Kenaf has been cultivated long, probably as early as 4000 BC in western Africa (Roseberg, 1996). This plant is known under a variety of names (Wilson and Menzel, 1964) such as mesta (India, Bengal), stockroot (south Africa), Java jute (Indonesia), and ambari (Taiwan). Next to cotton, is the most widely cultivated fiber plant in the open country and can be found from Senegal to Nigeria. The plant in Africa had several non-fiber uses. Leaves and flowers are used as a vegetable, its seed are used for oil production and various plant parts are used in medicines and in certain superstitious rites. According to Wilson (1978), kenaf occurs as a wild plant in Eastern Africa (Kenya and Tanzania) as a component of native vegetation. This crop was introduced into southern Asia around 1900. Principal production areas are China, India and the Tashkent area of the former USSR. Essentially, kenaf is a traditional third world crop that is poised to be introduced as a new annually renewable source of industrial fiber in the so-called developed economies.

1.2 Botanical description 1.2.1 Stems Kenaf stems are generally round, and depend on variety, thorns on the stems ranging from quite tiny to large such as on a black berry bush. Stem color varies from pure green to deep burgundy. Kenaf plants tend to grow as a single unbranded stem when planted at high production densities of 170,000 to 220,000 plants/ha with a height of 2.5 to 6m. Kenaf stems have a thin bark over a woody core, surrounded by a leaft tuft (Kaldor, 1989). Kenaf stems contain two major fiber types, the one contains long fibers situated in the cortical layer, and the other one contains short fibers located in the ligneous zone (Figure 1). The central area of the stem, corresponding to pith, consists of sponge-like tissue. The outer bark contains the bast fibers with an average length of 2.5mm and the woody core fibers with an average of 0.6mm. Kenaf fibers have three principal chemical constituents, which are the a-cellulose (58-63%), hemicelloluse (21-24%) and lignin (12-14%). The minor constituents in kenaf stems are 0.4-0.8% fats and waxes, 0.6 to 1.2% inorganic matter, 0.8-1.5% nitrogenous matter and traces

1 KENAF BOOKLET of pigments. In total these minor constituents account to about 2% (Stout, 1989). The core contains more lignin and less cellulose than the bark (Clark et al. 1971). The bast fiber compromises 35 to 40 % of the dry weight of the plant mature stem; and the core compromises the balance (Muchow, 1983 I). The fiber content of the kenaf bark content is about 50-55%, increasing according to the plant population density, while the less valuable short fibers make up about 45-60% of the inner core (Clark and Wolff 1969; Wood et al. 1983). Lower quality paper can be made from the short wood fibres of the core, while high quality paper can be made from the long fibres of the bark. Consequently, the core is more difficult to pulp than the bark, requiring more alkali and giving lower pulp yields; the resultant pulps are relatively slow draining with poor strength characteristics (Touzinsky et al. 1972; Bagdy et al . 1975).

Bark Core

Figure 1. Kenaf stem fractions (bark and core) for the variety Everglades 41. The separation was done by hand before the starting of the flowering phase (Source: CRES)

1.2.2 Leaves Leaf shape varies and strongly depends on the variety. Further to that, kenaf varieties are divided into two categories; the varieties (Everglades 71) with deeply lobed leaves (usually called split or divided) and varieties (Everglades 41) with shallowly lobed leaves (usually called entire) (Figure 2). The divided leaf shape can create a problem because it resembles marijuana. The entire leaf type has leaves that resemble those of its relatives like okra and cotton (Baldwin, 1994b). It should be pointed out that the first few juvenile leaves of all kenaf seedlings have more or less an entire shape.

1.2.3 Flowers and capsules The flowers (Figure 3) of section Furcaria are characterized by having a calyx with prominent central rib and two prominent marginal ribs. These rigid structures apparently are used for supporting the fragile and delicate petals. Also, the flowers of all species have more or fewer narrow bracts, which are borne below the calyx. The tip of these bracts may be unforked as in kenaf or forked, according to the sectional name Furcaria. More

2 KENAF BOOKLET specifically, the flowers of kenaf are typical of hibiscus, showing the characteristic fused statement column.

Kenaf v ariety with deeply lobed leaves that resembles marijuana

Kenaf variety with shallowly lobed leaves that usually called entire

Figure 2. View of kenaf variety with deeply lobed leaves and with shallowly lobed leaves (Source: CRES)

Figure 3. Kenaf flowers on the upper part of the plant stem (Source: CRES) The seed develops in five-lobular capsule. The capsules of cultivated varieties are generally indehiscent and remain intact for several weeks after reaching maturity. According to Baldwin (1994a) kenaf seeds take roughly 45 days to ripen. The seed is small (1.5-3.3 gr/100 seeds), black in color and subreniform in shape (Figure 4). The seed retains viability for about 8 months under ordinary storage conditions.

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Upper part of the stems with the capsules Seeds

Figure 4. Kenaf capsules and seeds for the variety G4 (Source: CRES)

1.2.4 Root The plant has a long effective tap root system and relatively deep, wide- ranging lateral root system making the plant drought tolerant. Further to that, kenaf with its tap root system is considered to be an excellent user of residual nutrients from previous crops . It is reported that kenaf root is very susceptible to root knot nematodes (Wilson and Summers 1966; Adenyi 1970; Adamson et al. 1974; Pate et al. 1958, Ibrahim et al 1982) caused by Meloidogyne incognita , Meloidogyne javanica and Meloidogyne arenaria . Nematodes are multicellular, microscopic, worm-like animals that feed mainly on plant root systems (Lawrence 1994). Leaves on plants infested with nematodes are yellow and fall. The infested plants are stunted and in case of a heavy infestation the plant may eventually die (Figure 5). The problem is particularly severe in light, sandy soils (Vawdrey and Stirling 1992). Disease epidemics probably develop relatively slowly in compacted clay soils because their texture appears to limit the capacity of nematodes to move from plant to plant (Wood and Angus 1974).

Infested roots Healthy root

Figure 5. View of roots that have been infested by nematodes (Source: CRES).

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1.3 Importance of the crop and state of the art of kenaf research in Europe and worldwide. Kenaf like all the other important fibre crops (jute, roselle, hemp, flax, ramie, etc.) can be pulped to make a range of paper and pulps comparable in quality to those produced from wood. With forests dwindling and the virgin wood become more expensive and the increasing demand for paper products it is understood why the non-wood fibre crops such as kenaf could are so important (Wood and de Jong, 1997, Fried 1999). Kenaf in a period of six months reach a plant height of 3 to 4 m and its production is two to three times higher (per ha and per year) than the southern pine forests (Fried, 1999). Although the importance of the crop is mainly referring to paper pulp production, kenaf is being characterized as a multi-purpose crop because it has a number of additional industrial applications. Thus kenaf fibers (either derived from the bark or the core of the plant stem) can be an excellent source for several other uses such as for fabrics, building materials (particleboards, low-density panels, wall paper backing, furntiture underlays etc.), bedding material, poultry and/or cat litter, oil absorbent, etc. (Kugler, 1988; USDA, 1988; Perry et al. , 1993; Kulger, 1996; Borazjani and Diehl, 1994; Ramaswamy and Easter, 1997; Kaldor et al. 1990). Additionally, the whole plant has high protein and good digestibility and may be pelletized (Webber and Bledsoe, 1991). Research work on kenaf is being carried out worldwide (USA, Australia, South America, Thailand, India and Japan). Early research started in the United States of America in the 1940s in order to use kenaf as a substitute to jute due to the supply distribution from the Far East during the World War II (Roseburg, 1996). In 1960 kenaf was selected by the United States Department of Agriculture from among 500 crop species (which included hemp) as the most promising non-wood fibre alternative for pulp and paper production. Since then, in the framework of national programmes, a large amount of research work has been carried out resulted in a complementary mechanized approach, which has reduced labor requirements and environmental impact. Nowadays, in USA more resources are asked for putting into work focusing on market development instead of the standard production research. In Australia the research on kenaf was initiated in 1972. The research was specifically directed towards growing the crop for the production of paper and the field program was supported by studies on the paper making properties of the stem material. The undertaken research has clearly confirmed the potential of kenaf as a feedstock for paper production and established the cultural practices necessary to cultivate the crop. The crop has not yet commercialized in Australia due to the fact that the Australian pulp mills are mainly based on wood (Wood, 1998). Kenaf has been accepted by the European Community as a “non-food” crop with high production of biomass, which is composed primarily of cellulose- rich stalk (Venturi, 1990; Webber, 1993). It has designated for utilization in the production of industrial fiber (EC Reg. 1765/92 of the Committee of 30 th

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April 1992 amended by EC Reg. 334/93 of the Committee of 15 th February 1993). The research at European level on kenaf started in the early 1990’s and the developments on the crop have been concentrated on the Mediterranean region with sub-tropical climates and have been focused mainly on the primary production in the framework of a European demonstration project that was aimed at testing kenaf as raw material for paper pulp production. In the view of this project (EUROKENAF) demonstrative fields were carried out in all the Mediterranean countries to produce the raw material for the paper pulp tests. According to the results derived from the cultivation of kenaf in the demonstrative fields it has been reported that the dry matter yields had been strongly depended on the maturity type of the cultivated variety and was ranged from 8 to 18 t/ha in Greece, from 12 to 17 t/ha in Italy, from 13 to 24 t/ha in Spain and from 12 to 20 t/ha in Portugal (Rego, 1998; Paschalidis et al ., 1997). The BIOKENAF project ( http://www.cres.gr/biokenaf ) offered an integrated approach for kenaf covering the whole production chain (production, harvesting and storage) testing the suitability of the crop for industrial products (high added value) and energy. This integrated approach was carried out taking into consideration the environmental and the economic aspects of the crop and through a market feasibility study was led to the production of industrial bio-products and biofuels with respect to security of supply and the sustainable land management. In Chapter 6 of the KENAF BOOKLET presented the main findings of this project.

1.4 Area of cultivation and world production According to FAO (2003) the main cultivation areas for kenaf are China, India, Thailand, Indonesia and Vietnam (Far East). It has been recorded (FAO, 2003) that the kenaf production in 1998/2000 was 0.51 million tons, among which production from China accounted for 44%, India for 39%, Thailand for 12 %, and the remaining were from Indonesia, Vietnam and other countries (Figure 6).

Kenaf World Production

China India Thailand Other

Figure 6. Main areas of kenaf cultivation in 1998-2000 (FAO, 2003). At that time the total production of jute, kenaf and other allied fibres (JAF) was 2.644 tonnes (Table 1) and the projection for 2010 is 2.342 tonnes that corresponds to a decrease on the growth rate -1.6% per year (2000-2010).

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Table 1. Total production of jute, kenaf and allied fibres (JAF) (FAO, 2003).

ACTUAL PROJECTED GROWTH RATES

PRODUCTION 1988-1990 1998-2000 2010 1988-90 to 1998-2000

Average Average 1998-2000 to 2010

000 tonnes Percent per year

WORLD 3311 2644 2342 -1.9 -1.6

Developing 3309 2637 2342 -1.9 -1.6

Africa 10 13 11 3.7 -1.2

L. America 58 26 18 -5.6 -3.2

Near East 8 4 0 -6.2 -6.3

Far East 3233 2595 2255 -1.9 -1.6

Bangladesh 850 768 721 - 0.9 -1.3

China 642 179 9 -14.8 -28.3

India 1472 1548 1494 1.4 -0.8

Nepal 16 15 18 0.7 0.3

Thailand 172 36 20 -17.7 -5.1

Vietnam 32 12 12 -9.8 0.1 Nowadays, it is not easy to find any huge kenaf cultivation area of kenaf producing countries like China and Thailand. It has been noticed that now kenaf is only planted on marginal lands with poor or no management (http://www.chinaconsultinginc.com ). Japan consumes nearly all of the Asian kenaf production. The Japanese industry has set a short-term goal of 1%, which would require about 300,000 tones of raw kenaf. In the longer term, the Japanese industry has set a goal of 10% (Wood, 1998). It is reported an area of cultivation of 1,000 ha in USA (Kugler, 1996). In 1999, an area of 2500 ha was planted in Texas, Mississippi and Missouri for a number of fiber applications. In 2000, almost 10,000 ha of kenaf are being cultivated in various parts of the United States. The four main areas of commercial kenaf activity in the U.S.A. are Georgia, Texas, Mississippi and New Mexico. In Australia there is no commercial production of kenaf and all the present fiber production is for experimental purposes. In Europe a cultivation area of 700 ha is being reported in Bologna (Italy). The harvested material is being used from the company KEFI ITALIA that is located close to Bologna to produce insulation mats from the bark material (http://www.kenaf-fiber.com ). In Italy there is another company working on kenaf namely “Agrikenaf Volturno” ( http://www.agrikenaf.it ) located close to Napoli.

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2. Eco physiological requirements of the crop

Although kenaf is capable of adapting itself to a large variety of climatic conditions, it is grows up best in tropical and subtropical regions since it is sensitive to frost. It is grown at latitudes from 45 0N to 30 0S (Mc Gregor 1976) (Figure 7) and at altitudes from the sea level to 1000m above the sea level. Areas where the plant is to be cultivated should be free or protected from strong winds, since the growth is rapid and the plants get so tall that they cannot stand much wind.

Figure 7. Zone that kenaf can successfully been cultivated. Kenaf is recommended for tropical and subtropical climates and for this reason it thrives best with air temperatures ranging from 15 to 27 0C during its growing period. The plant is frost sensitive and damaged by heavy rains and strong winds. Since the plant can be damaged by frost during the period of growth, sowing is generally not carried out until soil temperature exceeds 12 0 C (Angelini et al. 1998). Germination and seedling development are critical phases for kenaf and their duration is a function of temperature. The base temperature for kenaf germination has been reported as 9.2 0C (Angus et al. 1981) or 9.7 0C (Carberry and Abrecht, 1990). The needed precipitation level is 500-600 mm for a growing period of 4 to 5 months. Extremely heavy rains are also detrimental because they beat down the plants and caused difficulties in harvesting. Kenaf grows well on light to middleweight quickly warming soils and sandy soils also showing very good growth. A well-drained sandy-loam soil, about neutral in reaction (pH 6-7), with considerable quality of humus, appears to meet the requirements of kenaf better. Very wet soils are not suitable while kenaf cannot tolerate waterlogging especially in the early stages of growth. Moreover, kenaf does not perform well on soils with severe drainage problems. Fields with high weed levels should be avoided (Rehm and Espig, 1991). Good fertility contributes to higher yields (White et al. 1970; Dempsey 1975; Bhangoo et al . 1986). Kenaf was found to be moderately tolerant towards saline irrigation water (Francois et al . 1990).

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Although kenaf has been cultivated in many areas, the highest yields have been generally observed under the following conditions: Warm soil and air (mean daily air temperatures between 22 0 to 20 0C), sufficient moisture (monthly precipitation of 90-275mm), fairly high relative humidity 65-85%, a long frost free season, and fairly well drained soil which may otherwise vary greatly in texture and chemistry (Dempsey, 1975). The flowering of kenaf is indeterminate. Flowering of most kenaf varieties is under photoperiodic control. The plant remains vegetative until the daylight falls below 12h and 45min. Kenaf cultivars can be classified into early- maturity types (flowering in July) and late-maturity ones (flowering in September/October). To avoid reduced growth due to flowering and fruit formation, it is recommended that the day-length be greater than 12.5 hours during the growing season (Rehn and Espig, 1991). According to Whitely (1981) two weeks of very cloudy days will initiate flowering as day- length approaches 12.5 hours. On the contrary, photoperiodic does not influence the flowering of the early-maturity kenaf varieties. While photoperiod is the major factor determinant of the time to flowering, temperature has a modifying effect (Angelini et al., 1998). Kenaf yields vary widely worldwide. The interactions between local climate, crop management, cultivar, stand density, and plant mortality make it difficult to predict stem and fiber yield without field tests (Clark and Wolff, 1969; Higgins and White 1970; White at al. 1970; Dempsey 1975; Campbell and White 1982; Bhangoo et al. , 1986, Scott et al ., 1989). Commercial yields in the range of 9 to 22 t/ha biomass dry weights have often been reported. The higher yields were generally recorded when growing conditions were improved, typically as one moves from dry, high latitude locations to humid, lower latitude sites. In well-adapted areas, such as the southeastern U.S., kenaf has typically yielded three to five times more fiber per year than southern pine, the typically pulping raw material source in that area (Wolff, 1964; USDA 1993). Testing at several higher latitude temperate sites it is suggested that the adaptation of kenaf could change quite rapidly with a fairly small climatic change (White et al. , 1970; Lauer 1990; Evans and Hang, 1993). In southern Europe it has been reported production of 20 t/ha dry stem (Mambelli and Grandi, 1995; Manzanares et al., 1993). In other research works it has been reported up to 26 t/ha dry matter yields (Alexopoulou et al. 1999; Alexopoulou et al. 2000a, 2000b, Petrini et al. 1994 and Quaranta et al. 1998). In the framework of the BIOKENAF project a large number of field trials were conduced in Greece, Italy, Spain, Portugal and France and it was found that the recorded yields showed very large variations (from 6-25 t/ha dry stem yields) depending on the specific soil climatic conditions of each site. It should be also recorded that the highest yields were recorded in all sites when the sowing took place from the end of April until the end of May and any further delay in the sowing time after the middle of June resulted in great yields reduction ( http://www.cres.gr/biokenaf ).

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3. Management of the crop

3.1 Sowing dates and plant densities Kenaf seeds are relatively small and require good seed-soil contact for germination. Therefore, a fine, firm, well-prepared seedbed is necessary. The ground temperature should be 15 0C at least as warmer temperatures result in an increase in growth rate. Seed should be planted less than 1 inch deep, if the soil moisture and seedbed are suitable (Stricker et al ., 1998). Kenaf can emerge from a depth of 2.5 inches under the most favorable conditions. The importance of high quality seed (germination over 80%) of appropriate equipment that gives uniform seed placement and the good seed-soil contact should be overemphasized. It should be noted that warm, moist soils are the ideal planning conditions for kenaf. Kenaf plants that had been grown under no-till conditions resulted in lowest biomass accumulations. No-tillage systems may be a viable option in increasing acreage of kenaf, if weed problem is controlled and water is not a limited factor (Mosley and Baldwin, 1999). When kenaf is cultivated at a plant population ranges from 300,000 to 500,000 plants/ha, it is required a total quantity of 10-15 kg seed/ha. Kenaf is self-thinning and reduces its population during the growing season. A row spacing of 36 to 40 inches appears to be adequate. A 70% success rate results in a crop density of 30-35 plants per m 2. With good soil conditions, optimal temperature and moisture, plant emerges in 3 to 6 days.

Kenaf plots that were sown at the end of April 2004

Kenaf plots that were sown at the end of May 2004

Figure 8. View of kenaf plots (Greece) that were sown at the end of April 2004 and at the end of May 2004 (Source: CRES) The sowing date is strongly depends on the specific pedoclimatic conditions of the area of cultivation. Early planting dates often result in poor emergence and slow, non-competitive growth. On the other hand, the late planting dates will often results in reduced yield potential due to the reduced solar radiation availability. Due to the fact that the vegetative growth for the late-maturity kenaf varieties continues until the appearance of the first flowers (middle of September for the Mediterranean region), the

10 KENAF BOOKLET sowing should take place as soon as the soil temperature is higher than 15 0C in order the vegetative stage of the crop is as long as possible. According to the pedoclimatic conditions of southern EU, kenaf should be sown from late April to late May, depending on the field specific pedoclimatic conditions of the cultivation site (Figure 8). A large number of research works have been carried out worldwide in order to determine the appropriate plant population that results in maximization of the crop’s yields. In the view of this plant populations between 99,000 plants/ha to 932,000 plants/ha have been tested for several kenaf varieties throughout the world. In most of these research works it is reported that the increase of the plant density from 150,000 to 350,000 plants/ha resulted in maximization of the dry matter yields (Higgins and White, 1970; White, 1969; White et al. 1971; Bhangoo et al. 1986; Sarma and Boldoloi, 1995; Sarma et al. 1996). Sahih (1978, 1982, and 1983) reported that for maximum kenaf dry production in Sudan, the plant populations between 500,000 and 250,000 plants/ha were recommended for commercial production. At high densities it was observed that there were decreases in plant numbers (Scott, 1990) and moreover the number of branches per plant decreased (Fahmy et al., 1985). Higgins and White (1970) and White et al. (1971) found that the plant populations affected the plant height and the basal stem diameter that significantly decreased, while the percentage of dry matter at harvest increased (Naffes et al, 1983). Graham and Baldwin (1999) reported that the plant population and the row spacing were not found to effect the bast:core ratio of kenaf. Plants in stands that are too dense for the cultivar or seasonal growing conditions tend to be short, spindly and week-stemmed. Plants in stand that are too sparse produce branches that are too heavy. In both cases lodging is inevitable.

Figure 9. Unbranched kenaf stem in plots that the plant density was 400,000 plants/ha (Source: CRES). The choice of an optimum population (Muchow, 1979I; Muchow, 1979II; Muchow 1979III; Muchow 1980) must consider not only the response of the

11 KENAF BOOKLET components of yield, but also its influence on the growth form of the plant in terms of the ease of management. Since weeds can be efficiently controlled by pre-sowing or pre-emergence herbicides and insects may be controlled by aerial spraying, the only management factors requiring consideration are harvesting and handling. Also the lower the population was the greater the degree of branching was (Figure 9). This suggests that an intermediate population should achieve a satisfactory balance. A harvest population of 200,000 to 250,000 plants/ha is generally recommended.

3.2 Nitrogen requirements Kenaf, unlike traditional agricultural crops that are grown for their seed, is grown solely for its vegetation stalk. The removal of the nutrient–rich seed from the field results in significant removal of minerals (and fertilizers) from the source of production. The standing of the kenaf plants in the fields until the first killing frost resulted in defoliation of the stems. This drop returns significant quantities of nitrogen (as high as 4.0% by weight; Hollowell, 1997) calcium, magnesium, phosphate and potassium back to the soil where the stalks that remain prevent them from blooming away. Standing in the field allows returns of nutrients from the leaves that have already fallen and from the degradation of the non-fiber content of the bark. By the time the harvest arrives, the only thing removed from the kenaf field at harvest is the stalk, which derives from atmospheric components (cellulose, hemi cellulose, lignin=carbon, hydrogen and oxygen) (Dubard and Baldwin, 1999). Kenaf’s response to added fertilizers depends on the soil nutrient levels, cropping history and other environmental and management factors. A range of fertility responses has been reported. In general, added nitrogen has increased kenaf yields. Three important factors should be taken into consideration for kenaf fertilization. First of all, it should be pointed out that the fertility program should focus on vegetative needs of the crop than the grain or reproductive needs. Secondly, kenaf with its deep taproot and wide-spreading lateral root system is considered to be an excellent user or residual nutrients from previous crops. Last but not least, it should be taken into consideration the fact that the leaves that left in the field after the harvest can return 60-120 pounds of N/acre (Bhangoo et al. 1986) or 50-100 pounds of N/acre (LeMahiew 2000). According to Wood and Angus (1976), kenaf requirements for nitrogen are high, up to 30 kg N per tone of stem. Wood and Muchow (1980) also reported that the crop has a high requirement for nitrogen fertilizer; the amount depends on the yield of the crop at the harvest. As nitrogen fertilizer can constitute up to 20% of the cost of production of kenaf grown for paper pulp production, accurate prediction of optimal rates of application is needed. As with other crops proper fertility maintenance, especially for supplemental nitrogen application, is needed to optimize kenaf yields and minimize production cost. Reports so far are inconsistent relative to the effects of N on kenaf stalk yields (White and Higgins, 1965); researchers in Georgia have reported both positive (Adamson et al. 1979; Amankwatia and

12 KENAF BOOKLET

Takyi, 1975; Lakshminaray et al. 1980) and no benefits (Massey 1974, Webber, 1996). Studies in Florida demonstrated that the positive response to N applications on stalk yields were dependent on the soil type (Joyner et al. 1965), while kenaf grown on a sandy soil reported to N and did not respond to N on a peat soil. Bhangoo et al. (1986) in California and Sij and Turner (1988) in Texas increased stalk yields with the addition of N to soils with low available nitrogen. Stalk yields in Missouri (Ching and Webber 1993) on a silty clay soil and in Nebraska (Williams 1966) on a silty clay loam soil did not benefit from N applications. Stalk yields have also reported differently to N on the same location and soil throughout the years (Hovermale 1993). Chew et al. (1982) found that the nitrogen fertilization increased the plant height and the fibre yield of kenaf to the highest rate studied (112 and 120 kg/ha, respectively). K fertilisation increased kenaf height and fiber yield to 100 kg/ha at the 1-bloom stage, but to only 70 kg at the 5 to 10-bloom and seed set stages kenaf increased in height and fiber yield between the 1- bloom and seed set stages.

3.3 Irrigation requirements Crane (1947) stated that 500-625mm of rainfall over a period of 5-6 months is essential for a successful production of kenaf fibre. Haarer (1952) stated that a well-distributed rainfall of about 125 mm for each month during the growing season leads to optimum yield. A series of research works has been carried worldwide in order to determine both the maximization of the yields and the minimization of the applied irrigation water. Where irrigation water is scare or expensive (Muchow and Wood, 1981), the development of an effective water management strategy needs to consider both the crop response to irrigation frequency and the associated water application efficiency. When water is both plentiful and cheap the efficiency of application is of less significance but it is still of some economic importance. The efficiency of water application is inversely related to the frequency of application, and also usually inversely related to crop yield. It has been reported that the dry matter yields were higher when the plants irrigated well (Muchow, 1992; Robinson, 1990; Manzanares et al. 1993; Mambelli et al. 1995). Further to that it has been reported that the dry stem yields were linearly associated to the added irrigation water (Manzanares et al. 1993; Mambelli et al. 1995). Ogbonnaya et al. (1998) observed that the water deficit significantly reduced height and collar diameter growth of kenaf. Kenaf could be described as opportunistic in relation to water availability, with a high rate of stomatal conductance and transpiration when soil water is available but with markedly reduced leaf conductance and transpiration rate when water is limited. Kenaf was also observed to roll its leaves during drought. Muchow (1992) found that although the water deficit markedly reduced biomass production, the crop was able to recover following re-watering.

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Water stress is not always injurious. Although it reduces vegetative growth, it sometimes improves the quality of plant products. It can be generally hypothesized; therefore some level of stress may be required to improve the fibre qualities of crop plants. This level of stress, which does not affect growth, however, has to be worked out for each plant (Ogbonnaya et al. 1997). According to Muchow and Wood (1980), the water stress resulted in shorter kenaf plants, lower leaf area index, thinner stems and thicker leaves. In Figure 10 the effect of irrigation on plant development is presented in fields that were established in Greece. The plants that received 100% of PET had a plant height from 250 to 300 cm 10 days before the beginning of the flowering phase, while the plants that received only the 25% of had a plant height that did not exceed 170 cm. The percentage of bark in the stem material decreased only in the most stressed irrigation regime. This was associated with an increase in the dry matter content of the harvested material. It has been reported (Cook et al. 1998; Bhangoo and Cook, 1998a) that kenaf can be grown successfully on a saline soil when the irrigation water has good quality.

Irrigated plants Plants that received only (100% of PET) 25% of PET

Figure 10. Effect of irrigation on kenaf development (Source: CRES).

3.4 Weed management Like any other crop, weed control is vital to successful crop production. Kenaf is a vigorous growing plant and under optimum conditions it can form a canopy over the row middles is as little as 5 weeks (Neil and Kurtz, 1994).

14 KENAF BOOKLET

Once kenaf shades the row middles low, growing weeds and grasses are shaded out and there is no need for additional weed control. A pre or post emergence herbicide can be used, or a single hoeing after germination may prove sufficient for combating weeds. If a more persistent weed problem is present, hoeing twice may be necessary. This would be done after the kenaf is at least 15 cm high and the weed is in the germination leaf to 2-leaf stage. Because of kenaf’s fast growth, weeds are not much of a problem once the plant is established. In warm climates kenaf emerges and grows so rapidly that it competes with weeds effectively. In cooler climates and with earlier planting dates, cultivar and/or chemical weed control measures are more important. One weed species, which is especially competitive with kenaf, is velvetleaf, a relative of kenaf. At the seedling stage, velvetleaf and kenaf are very similar in appearance and rate of growth. Fields with high populations of this weed are not recommended for kenaf production. Cultural practices that are available to a producer (such as timely planting, narrow-row spacing, optimum fertilization, optimum plant populations, etc.) should be used to reduce weed problems. In the absence of herbicide registration for kenaf and particularly in cooler climates that the development of the crop is slow the mechanical weed control should be used. It should be noted that few herbicides are available for weed control in kenaf. In the USA, only Treflan EC, Treflan MTF, Treflan 5, Treflan TR-10, Trilin, Bueno 6 and Fusilade 2000 are currently labeled for use in kenaf. The last two herbicides are for post-emergence weed control, while the others are used for pre-plant weed control (Kurtz, 1994a and 1994b). A number of research works have been carried out in order to find out the best pre or post emergence herbicides for kenaf. According to Hickman (1990) the herbicides alachlor and metalachor may be the best solution for season long weed control of kenaf. It is also reported (Webber III, 1994) that triflualim and metalachlor provided excellent (>90%) weed control for moderate weed problems in stem yields. The herbicides cyanazine, diuron, fluometuron, lactofen, or prometryn can be used in kenaf production safety (Kurtz, 1996; Kurtz and Neill, 1992; Kurtz and Neill, 1990). If registration is obtained for these herbicides, they would very effectively control of a broad spectrum of grass and broadleaf weeds.

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4. Biomass yields and varieties

The selection of the best-adapted variety for each site is very important in order to provide the highest economic returns (Bhangoo and Cook, 1998). Breeders have produced many varieties, which vary in the form and color of the leaves, stems, flowers and seeds and in their response to soil conditions, climatic conditions and day length, as well as in the quality and yield of the fiber which they produce (Catling, 1982). Significant improvements in kenaf germplasm have been made since the first projects were initiated in the 1940’s in the USA. Major gains have been made in improving yield, bast fiber percentage, anthracnose resistance, lodging resistance, and tolerance to the root-knot nematode and soil fungi complex (Cook et al ., 1998). Although the present varieties are capable of achieving high biomass yields, there is interest in pursuing further improvement of both productivity and fibre quality through breeding activities because genetic gains can be exploited without a concomitant increase in the cost of the crop management (Pace et al . 1958). Heterosis in kenaf has already been observed (Pate and Joyner 1956; Nelson and Wilson 1965; Srivastava et al . 1978; Patil and Thombre 1980, 1981). The development of superior hybrids could therefore contribute to the improvement of kenaf productivity. Plant height, basal stem diameter, dry bark weight and the ratio between dry bark weight and the core weight are the major components of fiber yield and quality. In the USA there are over 240 varieties of kenaf, but only about 10 are commercially grown. In the U.S.A., the varieties used most extensively are those developed by ARS researchers in Florida, “Everglades 41” and “Everglades 71”. Both varieties are resistant to anthracnose. Since their development in the 1960s, there has been little variety development activity, although the ARS is initiating new breeding efforts. Genetic improvements for adaptation in northern environments may be feasible. Currently (USA), the principal commercial varieties are Everglades 41, Everglades 71, Tainung 1, Tainung 2 and Cuba 2032. In small quantities the photo-insensitive variety Guatemala 4 can be obtained. The recently released USDA line SF459 has not yet increased for commercial sales (Taylor, 1995). Kenaf varieties, according to their reaction to flowering, are divided in two groups the early and the late-maturity kenaf varieties.

4.1 Early maturity kenaf varieties The flowering for the early maturity kenaf varieties is irrelevant to the day- length. In the pedoclimatic conditions of the Mediterranean region, the early maturity varieties are characterized by flowering dates that began from mid-July to mid-August (Figure 11). The duration of the vegetative cycle may be 75-105 days (early varieties) or 105-120 days (semi-early varieties). Early maturity varieties have been produced for the Asiatic regions of the former USSR.

16 KENAF BOOKLET

In most research works, it is reported that the early maturity kenaf varieties are less productive than the late maturity kenaf varieties due to the fact that they have a shorter vegetative phase. Adamson et al. (1972) found that the early maturity kenaf varieties (PI 329195, PI 323129, PI 343139, PI 343142 and PI 343150) that have been tested among other kenaf varieties gave dry matter yields and that were always significantly lower than the recorded yields for the late maturity kenaf varieties (C-2032, Everglades 41 and G-4). More specifically, the dry stem yields for the early maturity kenaf varieties were 7.64 t/ha, while for the late ones were 17.9 t/ha. G4 is the only variety that combines a short growing cycle and a high productivity similar to those recorded for the late maturity kenaf varieties (Figure 11). In central north Italy (Petrini et al., 1994) has been reported dry yields of 24 t/ha for G-4. Grandall (1994) suggested that G4 is a photoperiod-insensitive cultivar. According to Belocchni et al. (1998), the early maturity G4 variety (in the Mediterranean region) needs from emergence to anthesis a period of about 130 days. Although in the United States and Southern Europe G4 is characterized as photo-insensitive with short growing cycle, in Australia it appears to be the opposite. It is suggested that the different conclusion of the control of flowering of G4 between Australian and United States researchers is due to the amphiphotoperiodic response that appears to alter the photoperiodic response in the two photoperiod regimes (Williams, 1994). However, in the areas of the United States that the research for kenaf has been carried out G4 flowers relatively rapid, due to the long days, with little radiation in thermal time to flower among sowings.

Plot with the new realized variety Gregg, Flowering in the flowering plot with the hasn’t started variety G4

Figure 11. Experimental field of kenaf in Greece in the beginning of September 2004; the plots of G4 variety were at the flowering phase from the middle of August, while in the plot of the late variety Gregg the stems were at the vegetable phase (Source: CRES)

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4.2 Late maturity kenaf varieties The flowering in the late maturity kenaf varieties strongly depends on the daylight length and the first flowers appear when day-length is under 12 hours and 30 min. The duration of the vegetative cycle for the late maturity kenaf varieties is 120-140 days. In the pedoclimatic conditions of the Mediterranean region the flowering for the late maturity kenaf varieties did not begin until the end of September (Figure 12). Consequently, the seed set on the top part of the stem did not ripen because of the beginning of the cold period (Siepe et al. 1997). The late-maturity kenaf varieties due to the fact that the vegetative growth lasts two months more produced significantly higher fresh and dry matter yields. It is reported (Pertrini et al., 1991) that there is a relation between kenaf productive and absence of the flower indication. This correlation can be understood when taking into consideration that kenaf has an indeterminate type of growth, which is rather rapid, until the first flowers appear. Afterwards, vegetative growth does not stop, but its growth rates decreases. Among the late-maturity kenaf varieties, the most known are Everglades 41, Everglades 71, Tainung 1 and Tainung 2. A large number of research works has been carried out with the aforementioned kenaf varieties. Between the kenaf varieties Everglades 41 and Everglades 71, it is reported that in most of the cases Everglades 71 was more productive. In Arizona (McMillin et al. 1998) Everglades 41 gave 23.4 t/ha dry matter yields and Everglades 71 24.0 t/ha. The superiority of Everglades 71 over Everglades 41 was also reported in another research work (Webber III, 1993). In this work, Everglades 71 gave dry matter yields of 15.9 t/ha and 14.5 t/ha Everglades 41. In central Greece, Everglades 71 gave 20.58 t/ha dry matter yields and Everglades 41 18.14 t/ha.

Late maturity Early maturity varieties at the end varieties at the end of October are at the of October are at end of the flowering the maturity phase phase

Figure 12. View of kenaf field at the end of October 2002; the late varieties are at the end of the flowering phase, while the early G4 is at the maturity phase (Source: CRES).

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Between the kenaf varieties Tainung 1 and Tainung 2, it should be pointed out that in most of the cases Tainung 2 was the more productive of the two. Further to that, in north-central Italy Tainung 2 gave almost 24 t/ha dry matter yields, while the corresponding yields for Tainung 1 was 21 t/ha (Petrini et al. 1994). In Mississippi (Ching, et al. 1993) both varieties (Tainung 1 and Tainung 2) have yielded the same.

4.3 New released varieties Recently, in the USA two newly kenaf varieties “Gregg” (Figure 13) and “Dowling” that were released appeared to be clearly superior to the other kenaf varieties in the later harvest (Scott et al. 1999). Further to that, it is reported that the two new kenaf varieties (Gregg and Dowling) released because of its improved total stalk yield and yield stability, high bast fiber percentage, moderate tolerance to the root-knot nematode and improved resistance to Cristulariella moricola. More specifically, the new variety “Dowling”, a cordate leaf genotype released because not only because of the improved total stalk fiber yield, the greater bast fiber percentage but also for it’s less susceptibility to lodging (Cook et al. 1999).

Figure 13. Leaves and flowers of the three realized kenaf varieties (Gregg, SF 459 and Dowling) (Source: Onalee’s Home Grown Seeds and Plants, http://www.onalee.com). Apart from the two mentioned varieties a third kenaf variety named SF 459 was released (Figure 13). SF 459 was selected for its high biomass yields and for its high resistant to nematodes.

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5. USES OF THE CROP

The main products of the crops are presented in Figure 14. Although the importance of the crop is mainly referring to paper pulp production, kenaf is being characterized as a multi-purpose crop because it has a number of additional industrial applications for both stem fractions. Thus kenaf fibers can be an excellent source for several other uses such as for fabrics, particleboards, bedding material, poultry and/or cat litter, oil absorbent, etc (Kugler, 1988; USDA, 1988; Perry, et al., 1993). Furthermore, kenaf as a fibrous crop appears to have enormous potential for becoming a valuable biomass crop of the future. Last but not least young kenaf plants can be used for animal feeding.

Figure 14. Kenaf products (Source: Photo courtesy USDA, http://www.kenaf.com/products.html) Kenaf pulps have been used for making several grades of paper including newsprint (Kugler 1989; Fuwape 1993), bond, coating raw stock and surfaced size (Figure 15). The results were positive, particularly in terms of paper quality, durability, print quality and ink absorption.

Figure 15. Newspaper (Bakersfield Californian) produced by kenaf (Source: http://www.naa.org/technews/tn950910/p18kenaf.html)

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The whole stem can be pulped or the bark (35% of the stem) and woody core (65% of the stem) can be separated and pulped separately. The quality of paper from the core and the bast fiber is quite different. It is reported that kenaf stems produce a pulp generally superior to hardwood pulps (apart from the resistance to tear) and comparable in many respects with softwood pulps (Badgy, 1999). The paper produced from core fibers is thin and dense, whereas the paper produced from bast fiber is thicker, lighter, and generally stronger (Han and Rymsza, 1999). When the two fractions of the stems are separated after the harvest, the core fraction can be used for energy production. The two stem fractions after separation are presented in Figure 16.

Figure 16. Kenaf stem fractions, bark on the left and core on the right after the separation (Source: Ankal Inc, http://www.kenaf.com/history.html). According to the literature, in order to make use of the excellent strength characteristics of kenaf bark in a range of high-value papers, chemical pulp is desirable (Shorton, 1981). The soda AQ trials (Kaldor, 1989; Saikia et al., 1995) with an environmentally friendly progress gave good results in terms of strength and yield (63%) especially for the bark. The core material was less suitable with poorer yield (46%), high chemical consumption and poor drainage, but good bonding properties. Blends of 65% and 35% core had generally intermediate properties and were acceptable for a range of applications (Kaldor, 1989). The soda–AQ pulping of Sudanese whole stalk kenaf produced pulps with good yield and strength properties with 14% active alkali charge as Na 20 (Kristova et al. 1998). Bark is the most valuable fibre component of the stem material and has a relatively low lignin of 9 to 10% and requires only a relatively mild pulping process. The wood fraction of the stem has a lignin content of 20-25% comparable to hardwoods. Rasaswamy et al. (1994, 1995) have shown that kenaf fibers can be mechanically processed, corded and made into yards and fabrics. The bast fibers can also be used for growing lawns and possibly for a fiberglass substitute. The core fibers can be used in the manufacture of particle boards, animal bedding, oil absorbent materials for oil speal clean up (Goforth, 1994), chicken liter, particle board and polting soil, a substitute for non-renewable peat moss.

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Kenaf fibers can be used in the manufacture as a substitute for fiberglass and other synthetic fibers. Losure and Hudson (1999) investigated the possibility of using kenaf bast fibers as fillers that can be combined with PVC to lower the cost of the resulting product without unacceptable loss of mechanical and physical properties (Figure 17). Adding fillers to plastics is a way to economize on the amount of plastic resin despite some loss of physic properties (Losure and Bartfield, 1998). Qualifying the loss of properties as a function of kenaf content will allow blends to design for economical use of resin, and ease of processing. According to Chow et al. (1998, 1999), kenaf can be used as filler in plastics for producing thermoplastic composite panels.

Figure 17. Kenaf bark fibers in plasticized PVC (Source: Mississippi State University, http://www.msstate.edu/Dept/EMC/kenafresin.html). Young plants can be used in forage applications (nutritious animal feeding) as a high protein crop (Hurse and Bledsoe, 1990; Philips et al. 1990). Dry matter digestibility is high and indicates that the fibre content is low even in the 70-day material. In kenaf trials, it was recorded excellent re-growth on plots cut between 40 to 70 days after sowing and it should be possible to obtain at least two and possible more cuts from the one sowing (Wood, 1975). In the digestion trials with sheep in Thailand, kenaf leaf material was compared with lucerne leaf material as a protein supplement for rice straw. The energy and protein in the kenaf-supplemented diet had highest digestibility although nitrogen retention was lower than with lucerne/rice straw diet (Wood, 1975). Grazing kenaf trials have been conducted in Mississippi. According to the results, it was found out that the advantage of kenaf is that it is able to get quality grazing until the end of November. This means less supplementation with hay and grain after grazing (Hovermale and Louis, 1999). The potential for mass production of oil as a byproduct of kenaf appears to be excellent. The relatively high oil content of the seeds (20%), the unique fatty acid composition that is similar to that of cottonseed oil, and the reasonable amounts of phytosterols and phospholipids suggest that kenaf oil can be used as a source of edible oil (Mohamed et al., 1995). The polyunsaturated fatty acid content (linoleic acid) is too low for it to be used

22 KENAF BOOKLET for polyunsaturated margarines but it would appear suitable for the vegetable fraction of margarine blends (Wood, 1975). Oil is also used in the manufacture of soap, linoleum, paints and varnishes, and for illumination. A wide range of new uses of kenaf has been tested worldwide recently. The latest developments on kenaf uses are presented below.
Kenaf can be used as a bedding material (Moore and Burcham, 1999). Having organic bedding is advantageous in most portable structures. Kenaf also tends to stay dryer than most organic bedding sources. Waldo et al. (1999) found that kenaf core can be an attractive source for equine bedding.
The kenaf core appears to be a potential raw material for low-density panels suitable for sound absorption type products (Sellers et al. 1995).
Kenaf core was compared to silica gel to determine suitability as a packaging desiccant (Williams et al., 1998). While silica gel absorbed more moisture than kenaf core, it appears that kenaf may be a suitable organic alternative to silica gel.
Recently has been designed and demonstrated a kenaf Medium Bioreactor Treatment System uses chopped whole-stalk as a medium in an attached-growth bioreactor. According to this work (Burcham et al., 1999), kenaf may provide a cost-effective means of odor reduction.
Borazjani and Diehl (1994) released that addition of kenaf to sandy soil contaminated with crude oil with or without added microorganisms could enhance biodegradation of total petroleum hydrocarbons in laboratory studies.
Kenaf core as a substrate for mushroom production showed good results (Sameshima et al., 1999). The mushroom yield increased by 86% over straight hardwood production when core was mixed with hardwood (80:20, respectively).
Inagaki et al. (1999) reported that a beautiful yellow dyed cloth (silk and cotton) was achieved from a 0.5 to 2% pigment solution extracted from the dry petals of the kenaf flower.

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6 Main results on the BIOKENAF research topics 6.1. Yielding potential of kenaf in South Europe In the BIOKENAF project a large number of kenaf trials for a period of four subsequent years were carried out in several sites in South Europe (Aliartos- Greece, Palamas-Greece, Catania-Italy, Bologna-Italy, Trieste-Italy, Estee Mons-France, Toulouse-France, Madrid-Spain, Extremadura-Spain and Lisbon-Portugal ) and the main findings presented below: 6.1.1 Effect of the sowing time The sowing time plays an important role on biomass yields and for yields maximization in South Europe the sowing time should take place from the end of April until the end of May. When the sowing time was postponed until the middle of July (like in Lisbon in years 2003 and 2004) the produced dry stem yields were quite low and did not exceed in any case the 6-8 t/ha (Figure 18).

22

20

18

16

14

12

10

8

6 Final dry stem yields (t/ha) yields stem dry Final

4

2

0 Early sowing Early Late sowing sowing Late Catania (IT)-S1 Catania (IT)-S2 Catania -S1 (ES) Madrid -S2 (ES) Madrid -S1 (PT) Lisbon -S2 (PT) Lisbon Bologna (IT) -S1 (IT) Bologna -S2 (IT) Bologna Palamas (GR) -S1 (GR) Palamas -S2 (GR) Palamas Aliartos (GR) - S1 - (GR) Aliartos S2 - (GR) Aliartos Figure 18. Effect of the two sowing dates (early and late) on kenaf dry stem yields (mean 2003-5, the vertical lines shows the variation among the years) (source: BIOKENAF network).

Plots that were sown at the end of May 2005

Plots that were sown at the end of June 2005

Figure 19.View of the field trial in early July 2005 in Catania (Source: University of CATANIA).

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It should be pointed out that when the two sowing times were late April and late May the recorded yields were higher in the case of the early sowing (Figure 18, this is quite clear in the case of Palamas-Greece and Bologna- Italy). The smallest effect of the early sowing on the yields was recorded in the case of Aliartos-Greece and Madrid-Spain. In Figure 19 a photo of the kenaf trial that carried out in Catania (early July 2005) is shown; half of the plots were shown at the end of May 2005, while the other half were sown at the end of June 2005.

6.1.2 Effect of plant density A plant density from 200,000 to 250,000 plants/ha can ensure high stem yields, unbranched stems as well as stems that are resistant to lodging. Two plant densities were tested (200,000 and 400,000 plants/ha) and the mean dry stem yields (averaged the years and the sites) were slighter higher in the fields with the low density. Only in two cases (Bologna-Italy and Lisbon- Portugal) the high density resulted in significant higher yields (Figure 20). 28 26 24 22 20 18 16 14 12 10

Dry Dry matter yields (t/ha) 8 6 4 2 0

Paris (FR) -P1 (FR) Paris -P1 (FR) Paris 200,000pl/ha 400,000pl/ha Lisbon (PT) -P1 (PT) Lisbon -P2 (PT) Lisbon Madrid (ES) -P1 (ES) Madrid -P2 (ES) Madrid Catania(IT)-P1 Catania(IT)-P2 Bologna (IT) -P1 (IT) Bologna -P2 (IT) Bologna Aliartos (GR) -P2 (GR) Aliartos Palamas (GR) -P1 (GR) Palamas -P2 (GR) Palamas Aliartos (GR) - P1 - (GR) Aliartos Figure 20. Effect of plant density (200,000 and 400,000 plants/ha) on dry stem yields (mean of 2003-5, the vertical lines show the variation among the years) (Source: BIOKENAF project).

6.1.3 Effect of Irrigation Irrigation is a critical factor for high stem yields achievement, especially in areas that in the summer months the rainfalls are very rare and the air temperature is higher that 30 0C and in these cases a total quantity of 250mm of water is needed for moderate yields. The irrigation effect on the stem yields was quite profound in the trials that took place in Madrid and Catania (Figure 21). It should be mentioned that in most of the trials that the irrigation rates was one of the tested factors statistical significant differences among the rates were recorded.

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25

20

15

10

5

0

2 0 3 0 3 1 1 3 1 3 I0 I1 I3 1 I2 s I s I2 s I ia a a id I1 n I n o a a ni ni dr o rtos I0 rt rtos I mas I m ta ta a b sbon I2 sbon I ean I a ia ia a a a a is i Mean I0M Mea Mean I3 Ali Al AliartosAl I2 al al Catan C CataniaC I Madrid MI Madrid MadridI2 I Lisbon LI Li L P PalamP

Figure 21. Effect of irrigation rate (0, 25, 50 and 75% of PET) on dry stem yields in five sites of South Europe (mean 2003-5, the vertical lines shows the variation among the years) (Source: BIOKENAF project).

6.1.4 Nitrogen effect Several nitrogen fertilization rates were tested. In four sites (Aliartos- Greece, Catania-Italy, Madrid-Spain and Lisbon-Portugal) three nitrogen rates were compared (0, 75 and 150 kg N/ha), while in two sites (Palamas- Greece and Palamas-Greece) four nitrogen rates (0, 50, 100 and 150 kg N/ha) were compared (Figures 22 and 23).

16

14

12

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8

6

4

2

0

Mean N0 Mean N1 Mean N2 Lisbon N0 Lisbon N1 Lisbon N2 Madrid N0 Madrid N1 Madrid N2 Aliartos N0 Aliartos N1 Aliartos N2 Catania N0 Catania N1 Catania N2 Figure 22. Effect of nitrogen rate (0, 75 and 150 kg N/ha) on dry stem yields in four sites of South Europe (mean 2003-5, the vertical lines shows the variation among the years) (Source: BIOKENAF project).

26 KENAF BOOKLET

25

20

15

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5

0

Mean N0 Mean N1 Mean N2 Mean N3 Mean Bologna N0 Bologna N1 Bologna N2 Bologna N3 Bologna

Palamas N0 Palamas N1 Palamas N2 Palamas N3 Figure 23. Effect of nitrogen rate (0, 50, 100 and 150 kg N/ha) on dry stem yields in two sites of South Europe (mean 2003-5, the vertical lines shows the variation among the years) (Source: BIOKENAF project). In most sites the nitrogen fertilization did not play any role on the achieved yields. The clearest effect of the nitrogen fertilization on yields was recorded in Aliartos, Madrid and Lisbon (Figure 22) and in these cases some statistical significant differences were recorded. In these cases the fields characterized by low fertility and had organic matter less than 1%.

6.1.5 Effect of variety The late maturity kenaf varieties were more productive compare to the early one (G4) (Figure 24). The new realized varieties (Gregg, Dowling and SF 459) had more or less the same productivity compared to the traditional late varieties (Tainung 2 and Everglades 41) and at the same time the variety SF 459 is a variety that is resistant to nematodes. In the 2004 and 2005 field trials that located in Aliartos-Greece the plants suffered from root nematodes apart from the plants of the variety SF 459.

20

16

12

8

(t/ha) yields Dry stem 4

0 Tainung 2 Everglades Gregg Dowling SF 459 G4 Mean 41

Figure 24. Effect of variety (Tainung 2, Evergldes 41, Gregg, Dowling, SF 459 and G4) on final stem yields (mean 2003-5, the vertical lines shows the variation among the years) (Source: BIOKENAF project).

27 KENAF BOOKLET

6.2. Development of a growth simulation model A new dynamic crop growth simulation model named “BIOKENAF” was developed and it is able to predict kenaf phenology, growth characteristics (leaf area index, soil water balance, etc.) and biomass yields (stems, leaves, petioles) under a wide range of soil climatic environments in Europe. This model was based on the Wageningen photosynthesis modeling approach and it can simulate biomass production under two productions situations: potential and water-limited. After the development of the BIOKENAF model the validation was carried out using data that were provided by all BIOKENAF partners from kenaf fields that were established in several sites in Southern Europe for the period 2003-5. In these trials, the growth and development of two important kenaf varieties (Tainung 2 and Everglades 41) were studied under two plant populations, two sowing dates, three irrigation and four nitrogen fertilization rates. The results on BIOKENAF model validation were quite encouraging, showing a good agreement between the measured and simulated data on dry biomass production per plant organ of kenaf (evolution throughout the growing period and final yields). Figure 26 demonstrates the good fit between measured and predicted values of dry biomass per plant organ of kenaf throughout the growing periods of the years 2003-2005 in central Greece. It is noticeable that the model assesses well the negative growth rates of leaves and total dry weight due to leaf senescence and to the low assimilation-respiration rate recorded at advanced development stages. The measured data of years 2003-2004 were used for model calibration whereas the data of 2005 can be used for model validation. It should be noticed, that model calibration is a difficult exercise since it is not sure that the field experimental data are always correct due to the experimental error involved, and therefore the slight variation between measured and calibrated values should not be attributed to model weakness. Surely, during model calibration, an effort was made towards better prediction of the dry matter yields during advanced development stages and of course of the final yields. Based to these considerations, the result of model validation for Greece 2005 (Figure 25) shows a very good fit (coefficient of determination equals to 95.5%) between measured and simulated total dry biomass yields of kenaf. The same holds for the examples of Italy (2003) and France (2005) for which model validation gives encouraging results (Figure 25). Note that the model may successfully predict dry matter variation from over 22 t/ha to lower than 8 t/ha in the different European environments, performing a substantial sensitivity required in such broad predictions. Particularly the model may predict quite successfully final biomass yields production as this is reflected by the high values of the relevant indexes: viz. r 2=95%, RMSE<15 and ME ~ 0.8).

28 KENAF BOOKLET

Figure 25. Measured versus Figure 26. Measured ( ○,□,×,+) and estimated total dry biomass simulated ( ______) dry mater production (kg/ha) throughout the growing in Palamas, central Greece period of kenaf in selected (2003−2005). Predictions refer to European sites and years potential production situation. ( ○): total, (□): stem, (×): leaf and (+): petiole dry weight. Note: data 2003, 2004 used for model calibration and data 2005 used for model validation.

29 KENAF BOOKLET

6.3. Harvest and storage trials Two different kenaf harvest systems were investigated in Trieste-Italy by CETA: a) mowing-chopping harvested with sheltered storage of the product and b) mowing-windrowing-baling . Both harvesting chains were performed in late winter (January-February) when the stems were defoliated, the moisture content of the stems were as low as possible and the fiber quality was not the best. In the previous European kenaf projects the fields used to be harvested in October when the fiber quality of the stem is the best. After the harvesting the stems left in the fields for few days in order to lose the leaves and the moisture content of the stems to be reduced (if the climatic conditions at that time were appropriate). The moving-windrowing-baling harvesting trial was carried out by using a Caspardo FBR 175 (the stems had a stem height 160 cm, basal stem diameter 12mm and moisture content 15%) and the harvested stems had to be baled (the bale chamber was 35 cm x 47 cm). It was characterised by a pick up width of 1.40m, a bale length adjustable (40-130 cm) and around 90 strokes per min by the plungerhead. It was failed to produce bales because the baler was broken due to the high kenaf mass that was picked up that caused a little plungerhead deviation and the following strokes caused the breaking of the baler.

Figure 27. View of the harvesting (mowing-chopping ) and storage trial in Trieste (Italy) and transportation to KEFI ITALIA premises (Source: CETA).

30 KENAF BOOKLET

The mowing-chopping chain was carried out by using a Janguar Claas 870 chopper that is usually used for maize in the area of the trial. This machine works 350 to 400 hours per year on maize with 70% moisture content and with a production flow 50-70 ton/ha chopped material. The chopped material had a size of 34 mm and it was transported to KEFI ITALIA premises to produce insulation mats from the bark with a variable density from 30 to 80 kg/m 3 (Figure 27). In KEFI premises it was possible to obtain the core fibre through a separation line. The whole harvesting chain was performed with a work capacity of 1.2 ha per hour. The bulk density was about 32 kg/m 3, while the chopped material had a moisture content of 12.2%. Two storage trials were carried out: a) storage the chopped material with size 34 mm in a pile covered by a plastic sheet and b) sheltered the chopped material (10 and 34 mm) in a storehouse. In Figure 27 the chopped material before transporting to KEFI premises was piled up near the field border. The chopped material is a really soft material and in order to reduce the pile volume the pile was compacted by power shovel. Afterwards, the pile was covered with a plastic sheet, normally used to cover the ensiled maize to prevent the chopped material from becoming damp from rainfalls or snow. The low moisture content of the chopped material during harvesting did not allow any fermentation process to start inside the pile. During the sheltered of the chopped material (10mm and 34 mm) in a storehouse biodegradation of biomass was occurred due to the microbial activity. During the storage period no fermentation process started inside the piles, probably due to low moisture content at the harvest (17%). The moisture content (%) of the stored material after two months storage was reduced to 16% (Figure 28).

Figure 28. Storage trial of the chopped material (10 and 34 mm) in a storehouse (Source: CETA)

31 KENAF BOOKLET

6.4. Suitability of kenaf for selected industrial applications Taking into account that fibres might be weakened during the winter period in the field, the application of fibres in insulation mats is technically and economically one of the best options. The use kenaf core particles as absorber material are the most promising application of kenaf core. BIOKENAF project focussed on the quality of the fibres , the application of kenaf bast fibres for insulation mats and kenaf core as absorption particles and did some tests with kenaf fibres in compounded composites .

Fibre extraction It has been shown that kenaf fibres can be extracted from kenaf stems that were harvested after winter without additional retting. Both on laboratory and industrial scale fibre extraction was carried out without any problems. After decortication the fibres still contained about 11% (w/w) of core particles.

elementary fibre microfibril Ø 4 - 10 nm elementary fibre Ø 7 - 35 µm kenaf stem Ø 10 - 15 mm

CH 2OH CH OH bast fibre bundle O 2 O HO O O Ø 50 - 150 µm HO HO OH OH wood cellulose AB 55 - 60% cellulose AA 13 - 15% hemicellulose AD 2 - 5% pectin bast AC 9 - 13% lignin pith

Figure 29. Schematic composition of kenaf stem and bast fibre (Source: A&F)

Insulation mats No problems were met in producing insulation mats made of kenaf fibres with 11% (w/w) core particles and these kenaf fibre mats show a thermal conductivity close to commercial products from other fibres (Figure 30). In spite of the quite high amount of core particles, the kenaf mats have satisfying insulation properties.

Figure 30. Bark material after separation in KEFI ITALIA premises on the left and insulation mats that produced from this material on the right (Source: Reports of A&F, BIOKENAF project).

32 KENAF BOOKLET

In insulation mats made from natural fibres, the moisture absorption under humid conditions depends more on the applied additives like fire retardants than on the origin of the natural fibres. Test show that especially when fire retardants have to be used good ventilation on the outside of the mat is a necessity to avoid build up of moisture in the mat, resulting in microbiological decay.

Fibre quality Fibres are affected by micro-organisms during the winter period in the field (Figure 31), resulting in weaker fibres bundles with much heterogeneity. In tensile tests, the cell wall of the elementary fibres break apart they are weaker than the bonds between the elementary fibres. No difference in fibre strength was found by additional warm water retting. To ensure sustainable kenaf fibre business a broader range of possible applications must be developed by improving the quality of the fibres. Higher quality fibres might be achieved by studying and developing new retting and extraction processes.

Figure 31. Affected kenaf stems on the left and unprotected fibre bundles on surface of kenaf stem on the right (Source: A&F). Composites Test with kenaf fibres in PP compounds show acceptable strength properties (Figure 32). No differences were found in strength properties of kenaf/PP composites between kenaf fibres harvested before and after winter. However because of the limited amount of samples and tests, these experiments need to be confirmed. The tested kenaf fibres can compete with other natural fibres on flexural strength properties, but not on impact strength.

Figure 32. Composite test pieces (Source: A&F)

33 KENAF BOOKLET

Absorption Absorption experiments show that kenaf core particles have water absorption and water retention characteristics in the range of those of commercial bedding materials. The large kenaf core particles show higher water retention values, but this product contains too much bast fibres and it is too coarse to be used as animal bedding. These large particles should be reduced in size in the beginning of the separation process. Absorption experiments show that kenaf core particles can be used as oil spill absorber, but they need a size reduction to below 2 mm to be as efficient as other natural absorbers like straw, wood shavings, flax core and hemp core. Kenaf /polyester mats show high absorption capacity for oil. They can be pressed out and re-used at least six times without loosing their absorption capacity.

6.5. Thermochemical kenaf applications The measured ash content for kenaf core material was 2.0%, while for the whole stem was 2.4% and both these values considered relatively low. Kenaf –in particular the whole plant material - has a very low bulk density. This has not only consequences for the operation of the gasification, combustion and pyrolysis reactor itself, but also for the system that feeds the biomass to the reactor. Due to the low bulk density of the material it will probably not flow freely and the risk of bridging is significant. Also the actual feeding rate might be lower than with e.g. wood chips. A fluidised bed gasifier/combustor and a pyrolysis reactor are sensitive to irregular feeding. Combustion: Based on the composition of the whole plant material, it is expected that the high nitrogen content in the whole plant material may cause quite high NO x levels even in a commercial (Figure 33), optimised installation (a maximum content of 300 ppm NO x is expected).

4

3 H2 CO 2 CH4

1 C2+ concentration[vol%]

0.7 0.8 0.9 1 1.1 1.2 1.3 Lambda [-]

Figure 33. Combustion of Kenaf core material; hydrogen, CO, CH4 and C2+ as function of lambda (Source: BTG)

34 KENAF BOOKLET

Gasification: Whole plant material is considered as a difficult material to feed in the gasifier/combustor. For an industrial installation further pre- treatment may be desired. Core material can be used as such and no further pre-treatment is needed. The core material behaves very much the same as other energy crops like Arundo, Switchgrass and Miscanthus. Chlorine could not be detected in the product gas. One explanation might be that chlorine is captured by calcium and/or magnesium. Pyrolysis: The total oil yield is relatively high compared to other energy crops (like Miscanthus, Arundo, Switch grass, straw ~ 45 – 55 wt%), but low compared to wood (~70wt%). The mass balance closure is 113 %, which is mainly due to uncertainty in the amount of charcoal formed. Charcoal is not removed from the system and used for internal heating. The charcoal produced is calculated from the flue gas composition. The oil has not been analysed in detail, but based on the analysis of the kenaf quite some fuel nitrogen can be expected in the oil. Combustion of the kenaf oil may result in high NOx emissions.

6. Environmental analysis and LCA The energy balance is relatively insensitive to variation in cultivation, but highly sensitive to biomass productivity, transportation and final end use and disposal. When the yields were increasing the balance was improving. The time of sowing and the level of irrigation are the main crop management factors that affect biomass yields. So, these factors should be addressed particularly in the production phase, in order to obtain a better energy balance. The transportation distance increment will also worsen the balance. Detailed consideration of the energy balances suggests that the use of kenaf-fibres for the production of thermal insulation boards are favoured over its use as an energy feedstock or as pulp for paper, where energy balances may be poor. Also, kenaf for energy and for pulp for paper, are not yet, current industrial end uses in the Mediterranean Region, by opposition to the use of kenaf for the production of thermal insulation boards. The life-cycle impacts of kenaf board have been compared with the performance of a synthetic insulating product, such as polyurethane. According to those results, Kenaf board production offers considerably greater GHG emission reduction potential and acidifying gas emission reduction potential, compared with polyurethane, and appears to represent an efficient land-use option for this purpose. Net total emissions were relatively insensitive to variation in cultivation emissions, but highly sensitive to the productivity of the fields, transportation and final disposal, as observed for the energy balance. Irrigation level and time of sowing are, again, the production phase factors that may affect, significantly, the results obtained. Kenaf appears to represent an efficient land-use alternative in the Mediterranean Region. Results showed that a sustainable production of kenaf is promising when kenaf is grown on set-aside or on surplus agricultural land following CAP reforms (like grassland and tobacco cultivation) and when kenaf-fibres are used for the production of thermal insulation boards.

35 KENAF BOOKLET

3.7 Economic analysis of the crop

The economic analysis was based on data that were collected from fields that had a size of 2ha and were located in Orestiada-Greece, Thessaloniki- Greece, Trieste-Italy and Madrid-Spain. The main results of the economic analysis are the followings: • Market opportunities have been identified for kenaf as a fuel, in the manufacture of paper, tea bags, and as a fibre-glass substitute. Kenaf also is a viable feedstock for chemical pulp mills for the production of speciality paper. • High yields of 18 t/ha and above may be economically viable for kenaf as an energy crop on large farms. • Moderate yields of 14 t/ha will be economically viable for kenaf if the product price is 80 euro per dry tone (Figure 34). • There is an opportunity to increase gross margins/ha by optimizing the seed, fertilization and irrigation (Table 2).

Table 2. Gross margin for Kenaf (€/ha) (figures taken from actual inputs made to 2 ha areas of Kenaf grown within the project) (Source: ADAS). Activity Mean Orestiada Thessalonika Spain Italy Greece Greece

Total variable costs 836 895 845 741 558

Revenue Price /t 80 80 80 80 80 Yield t/ha 13.1 12.0 14.0 19.0 7.3 Total Revenues from Sales 1045 960 1120 1520 581

Gross Margin (excluding 298 65 275 787 67 subsidies)

180 Project mean 150 Optimal 120

90

60

30 Production Production costs (€/tonne) 0 0 5 10 15 20 25 Yield (t/ha)

Figure 34. Influence of yield on variable costs of Kenaf

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