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Bioconversion of eucalyptus bark waste into soil conditioner
Bioresource Technology 81 (2002) 163±165
Short communication
Bioconversion of eucalyptus bark waste into soil conditioner K.R. Yadav a, R.K. Sharma a, R.M. Kothari b,* a Prathista Industries Ltd., S.P. Road, Secunderabad 500 003, India School of Life Sciences, North Maharashtra University, P.O. Box No. 80, Jalgaon 425 001, India
b
Received 21 November 2000; received in revised form 20 March 2001; accepted 28 March 2001
Abstract An optimized protocol for the bioconversion of eucalyptus bark was devised. It comprised: (i) mechanical reduction in bark size to 0.5±3.0 cm, (ii) moistening to 60±65%, (iii) forti®cation with ligninase-rich fungus Volvariella sp. (S-1) and 2% urea and (iv) maintenance of this composting mix under aerobic and ambient condition for 14±15 weeks. The resulting bark soil conditioner (BSC) was an easily crumbling, reddish brown biomass, with physico-chemical and microbial properties which would enrich soil fertility/productivity. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: Eucalyptus bark; Composting; Bark soil conditioner
1. Introduction
2.2. Chemicals and reagents
Bamboo, a preferred raw material of the paper industry in India, has become scarce because of indiscriminate felling over a prolonged period. It is substituted by eucalyptus wood which has rapid growth rate, permitting 7 years harvesting cycle, and needs minimal engineering changes in pulp mills. However, it needs debarking prior to pulping for quality paper, thereby generating bark at about 15±20% of eucalyptus wood utilized. With an estimated 2.5 million tonnes of eucalyptus wood used per annum, about 0.3±0.5 million tonnes of bark is generated. In view of its negligible alternative use, easy and economical availability and scanty literature on conversion into soil conditioner (SC), its use as a raw material for bioconversion into SC has been explored in the present study.
Fertilizer grade urea, soybean ¯our (SBF), corn steep liquor (CSL), Tween-80 and tap water were used. Analytical reagent (AR) grade chemicals and demineralized (DM) water were used for analyses.
2. Methods 2.1. Eucalyptus bark
*
2.3. Microbial cultures Six ligninase-rich fungi [Pleurotus ostratus (P-1), Pleurotus sajar caju (P-2), Pleurotus ¯orida (P-3), Volvariella volvaceae (Vv), Volvariella sp. (S-1) and Volvariella sp. (S-2)] were screened for identifying the most ecient species for the bioconversion of bark into SC. 2.4. Inoculum preparation An inoculum of each culture was grown (27 1°C, 80±100 rpm, 24 h) in a pre-sterilized and optimized medium, comprised of 0.5% SBF (w/w), 1% CSL (v/v) and 0.01% Tween-80 (v/v), adjusted to pH 5.5.
It was procured from local debarking sites.
2.5. Typical experimental set up
Corresponding author. Tel.: +91-257-252193; fax: +91-257-252183. E-mail address: [email protected] (R.M. Kothari).
It comprised reduction of 10 kg eucalyptus bark to 0.5±3.0 cm size pieces by mechanical cutter, moistening with tap water to 60% moisture, inoculation with 1 l of exponentially growing fungal culture, addition of 2% urea to serve as a nutrient for the inoculum,
0960-8524/02/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 0 - 8 5 2 4 ( 0 1 ) 0 0 0 6 1 - X
164
K.R. Yadav et al. / Bioresource Technology 81 (2002) 163±165
thoroughly mixing these four ingredients and placing the mix for decomposition in pits 30 30 30 cm3 under ambient conditions. The temperature in the composting mix was monitored once a week and an adequate amount of water was sprinkled to maintain 60% moisture.
mamurthy et al., 1998), reducing sugars (Miller, 1959) and nitrogen (Jayaraman, 1992).
3. Results and discussion 3.1. Composition of bark
2.6. Bioecacy study Progress of bark soil conditioner (BSC) formation was monitored at 3-week intervals from growth pro®les of a high yielding variety of wheat (HD 2329, Triticum aestivium) in a plant growth chamber (NSW, New Delhi). The growth of wheat seedlings in only soil was regarded as master control, that in soil + bark (75:25, v/v) without any culture was regarded as control and that in soil + bark (75:25, v/v) forti®ed with a particular culture were regarded as experimental (Sharma et al., 1994). Besides height, chlorophyll and root rami®cation of 3week old wheat seedlings were measured. When the growth inhibitory eect of bark was abolished, BSC formation was regarded as complete. 2.7. Analytical methods
Analyses of bark are given in Table 1. From Table 1, it was clear that with a high amount if lignin and extractables, the conversion of bark into BSC would be a slow process (Ramamurthy et al., 1998). 3.2. Wheat seedlings growth Cultures of fungi and pro®les of composting as judged from the height of wheat seedlings suggested S-1 to be the ecient fungus (Table 2). The eciency of S-1 over other cultures was reproducible and supported by pro®les of root rami®cation, shoot biomass and chlorophyll contents of wheat seedlings (Fig. 1). Plants grown on BSC obtained using S-1 showed more vigour, lateral shoots and extensive rami®cation of root system. 3.3. Optimized protocol for BSC preparation
Bark was analyzed for cellulose (Updegra, 1969), hemicellulose (Deschatelets and Yu, 1986), lignin (RaTable 1 Chemical analysis of eucalyptus bark 37.4a 19.2 5.5 62.2 28.0 4.9 1.1 15.5 7.2 93.2
Cellulose Hemicellulose Free sugars Total carbohydrates Lignin Ash Total nitrogen Water extractables Alcohol extractables Total organic matter
a An average of three analyses, expressed as percent (w/w) on dry weight basis.
An optimized protocol for BSC preparation needed decomposition of bark pieces (0.5±3.0 cm size) forti®ed with 2% urea, around 65% moisture, by S-1 inoculum (bark:inoculum 10:1) under aerobic and ambient conditions for 14±15 weeks. Turning once per week in initial 2 weeks expedited decomposition by 2 weeks. This is in accordance with the observations made by Guedes de Carvalho et al. (1991). While eucalyptus stem dust needed 6±8 weeks for composting (Ramamurthy et al., 1996), bark needed 14± 15 weeks. This delay was due to presence of more lignin, less sugars and extractables (such as resins, terpenoids and phenolics) in bark (World Bank Report, 1995). Scale-up of this protocol to 500 kg was reproducible, without any technical diculties.
Table 2 Wheat seedings' growth in composting media of dierent ages Duration
3-Weeks
6-Weeks
9-Weeks
12-Weeks
15-Weeks
Culture
Av. height (cm)
Av. height (cm)
Av. height (cm)
Av. height (cm)
Av. height (cm)
Master control Control P-1 P-2 P-3 Vv S-1 S-2
13.9 6.9 8.2 8.9 9.1 10.5 11.5 11.2
14.2 6.5 11.3 11.2 11.5 12.2 13.8 12.9
14.5 6.8 12.5 11.9 12.2 13.2 16.9 16.1
14.6 7.3 13.7 12.9 13.0 14.3 18.5 17.5
15.2 7.9 14.5 14.2 14.3 15.8 19.9 18.1
P-1 Pleurotus ostratus; P-2 Pleurotus sajar caju; P-3 Pleurotus ¯orida; Vv Volvariella volvaceae; S-1 Volvariella sp. and S-2 Volvariella sp. Bold type indicated the most ecient fungus composting eucalyptus bark.
K.R. Yadav et al. / Bioresource Technology 81 (2002) 163±165
165
Fig. 1. Histogram depicting height, biomass and chorophyll content of wheat seedlings as a function of BSC, derived from three cultures. S-1 Volvariella sp.; S-2 Volvariella sp. and Vv Volvariella volvaceae.
3.4. Properties of BSC
References
The BSC was a partially decomposed solid, organic, dark brown mass. It imparted porous texture and water holding capacity to soil, thereby promoting root rami®cation and sustained growth rate. Microscopy revealed the presence of Pseudomonas, Aspergillus, Penicillium and Bacillus in decreasing number as the major bene®cial microbes, earlier observed by others also (Davis et al., 1992; Kostov et al., 1994).
Davis, C.L., Hinch, S.A., Donkin, C.J., Gerishuizen, P., 1992. Changes in microbial population numbers during the composting of pine bark. Bioresour. Technol. 39, 85±92. Deschatelets, D.L., Yu, E.K.C., 1986. A simple pentose assay for biomass conversion studies. Appl. Microbiol. Biotechnol. 22, 379± 382. Guedes de Carvalho, R.A., Gonzales Beca, C.G., Naves, O.R., Sol Pereira, M.C., 1991. Composting of pine and eucalyptus bark. Bioresour. Technol. 38, 51±63. Jayaraman, J., 1992. Laboratory Manual in Biochemistry. Wiley Eastern Press, Bombay. Kostov, O., Petkova, G., Vancleemput, O., 1994. Microbial indicator for saw dust and bark compost stability and humi®cation processes. Bioresour. Technol. 50, 193±200. Miller, G.L., 1959. Estimation of reducing sugars by dinitrosalicylic acid. Anal. Chem. 31, 426±428. Ramamurthy, V., Sharma, R.K., Yadav, K.R., Kaur, J., Dev Vrat, V., Kothari, R.M., 1996. Volvariella treated eucalyptus saw dust stimulates wheat and onion growth. Biodegradation 7, 121±127. Ramamurthy, V., Sharma, R.K., Kothari, R.M., 1998. Microbial conversion of ligno-cellulosic wastes into soil conditioners. In: Pandey, A. (Ed.), Advances in Biotechnology. Educational Publication, New Delhi, pp. 433±438. Sharma, R.K., Yadav, K.R., Kothari, R.M., 1994. Innovative recycling of vegetable protein waste for increased productivity. Technovation 14, 31±36. Updegra, D.M., 1969. Semi-micro determination of cellulose in biological material. Anal. Biochem. 32, 424±428. World Bank Report of bark and saw dust composting, vol. 264, 1995, pp. 63±65.
4. Conclusion An optimized, simple, cost-eective and eco-friendly protocol was developed for the bioconversion of eucalyptus bark into soil conditioner. In view of its physico-chemical and microbial characteristics, it releases nutrients for rhizospheric microbes and plants for rapid growth on sustained basis. Acknowledgements The authors are grateful to Professor S.F. Patil, ViceChancellor, North Maharashtra University, Jalgaon for providing experimental facilities.
Short communication
Bioconversion of eucalyptus bark waste into soil conditioner K.R. Yadav a, R.K. Sharma a, R.M. Kothari b,* a Prathista Industries Ltd., S.P. Road, Secunderabad 500 003, India School of Life Sciences, North Maharashtra University, P.O. Box No. 80, Jalgaon 425 001, India
b
Received 21 November 2000; received in revised form 20 March 2001; accepted 28 March 2001
Abstract An optimized protocol for the bioconversion of eucalyptus bark was devised. It comprised: (i) mechanical reduction in bark size to 0.5±3.0 cm, (ii) moistening to 60±65%, (iii) forti®cation with ligninase-rich fungus Volvariella sp. (S-1) and 2% urea and (iv) maintenance of this composting mix under aerobic and ambient condition for 14±15 weeks. The resulting bark soil conditioner (BSC) was an easily crumbling, reddish brown biomass, with physico-chemical and microbial properties which would enrich soil fertility/productivity. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: Eucalyptus bark; Composting; Bark soil conditioner
1. Introduction
2.2. Chemicals and reagents
Bamboo, a preferred raw material of the paper industry in India, has become scarce because of indiscriminate felling over a prolonged period. It is substituted by eucalyptus wood which has rapid growth rate, permitting 7 years harvesting cycle, and needs minimal engineering changes in pulp mills. However, it needs debarking prior to pulping for quality paper, thereby generating bark at about 15±20% of eucalyptus wood utilized. With an estimated 2.5 million tonnes of eucalyptus wood used per annum, about 0.3±0.5 million tonnes of bark is generated. In view of its negligible alternative use, easy and economical availability and scanty literature on conversion into soil conditioner (SC), its use as a raw material for bioconversion into SC has been explored in the present study.
Fertilizer grade urea, soybean ¯our (SBF), corn steep liquor (CSL), Tween-80 and tap water were used. Analytical reagent (AR) grade chemicals and demineralized (DM) water were used for analyses.
2. Methods 2.1. Eucalyptus bark
*
2.3. Microbial cultures Six ligninase-rich fungi [Pleurotus ostratus (P-1), Pleurotus sajar caju (P-2), Pleurotus ¯orida (P-3), Volvariella volvaceae (Vv), Volvariella sp. (S-1) and Volvariella sp. (S-2)] were screened for identifying the most ecient species for the bioconversion of bark into SC. 2.4. Inoculum preparation An inoculum of each culture was grown (27 1°C, 80±100 rpm, 24 h) in a pre-sterilized and optimized medium, comprised of 0.5% SBF (w/w), 1% CSL (v/v) and 0.01% Tween-80 (v/v), adjusted to pH 5.5.
It was procured from local debarking sites.
2.5. Typical experimental set up
Corresponding author. Tel.: +91-257-252193; fax: +91-257-252183. E-mail address: [email protected] (R.M. Kothari).
It comprised reduction of 10 kg eucalyptus bark to 0.5±3.0 cm size pieces by mechanical cutter, moistening with tap water to 60% moisture, inoculation with 1 l of exponentially growing fungal culture, addition of 2% urea to serve as a nutrient for the inoculum,
0960-8524/02/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 0 - 8 5 2 4 ( 0 1 ) 0 0 0 6 1 - X
164
K.R. Yadav et al. / Bioresource Technology 81 (2002) 163±165
thoroughly mixing these four ingredients and placing the mix for decomposition in pits 30 30 30 cm3 under ambient conditions. The temperature in the composting mix was monitored once a week and an adequate amount of water was sprinkled to maintain 60% moisture.
mamurthy et al., 1998), reducing sugars (Miller, 1959) and nitrogen (Jayaraman, 1992).
3. Results and discussion 3.1. Composition of bark
2.6. Bioecacy study Progress of bark soil conditioner (BSC) formation was monitored at 3-week intervals from growth pro®les of a high yielding variety of wheat (HD 2329, Triticum aestivium) in a plant growth chamber (NSW, New Delhi). The growth of wheat seedlings in only soil was regarded as master control, that in soil + bark (75:25, v/v) without any culture was regarded as control and that in soil + bark (75:25, v/v) forti®ed with a particular culture were regarded as experimental (Sharma et al., 1994). Besides height, chlorophyll and root rami®cation of 3week old wheat seedlings were measured. When the growth inhibitory eect of bark was abolished, BSC formation was regarded as complete. 2.7. Analytical methods
Analyses of bark are given in Table 1. From Table 1, it was clear that with a high amount if lignin and extractables, the conversion of bark into BSC would be a slow process (Ramamurthy et al., 1998). 3.2. Wheat seedlings growth Cultures of fungi and pro®les of composting as judged from the height of wheat seedlings suggested S-1 to be the ecient fungus (Table 2). The eciency of S-1 over other cultures was reproducible and supported by pro®les of root rami®cation, shoot biomass and chlorophyll contents of wheat seedlings (Fig. 1). Plants grown on BSC obtained using S-1 showed more vigour, lateral shoots and extensive rami®cation of root system. 3.3. Optimized protocol for BSC preparation
Bark was analyzed for cellulose (Updegra, 1969), hemicellulose (Deschatelets and Yu, 1986), lignin (RaTable 1 Chemical analysis of eucalyptus bark 37.4a 19.2 5.5 62.2 28.0 4.9 1.1 15.5 7.2 93.2
Cellulose Hemicellulose Free sugars Total carbohydrates Lignin Ash Total nitrogen Water extractables Alcohol extractables Total organic matter
a An average of three analyses, expressed as percent (w/w) on dry weight basis.
An optimized protocol for BSC preparation needed decomposition of bark pieces (0.5±3.0 cm size) forti®ed with 2% urea, around 65% moisture, by S-1 inoculum (bark:inoculum 10:1) under aerobic and ambient conditions for 14±15 weeks. Turning once per week in initial 2 weeks expedited decomposition by 2 weeks. This is in accordance with the observations made by Guedes de Carvalho et al. (1991). While eucalyptus stem dust needed 6±8 weeks for composting (Ramamurthy et al., 1996), bark needed 14± 15 weeks. This delay was due to presence of more lignin, less sugars and extractables (such as resins, terpenoids and phenolics) in bark (World Bank Report, 1995). Scale-up of this protocol to 500 kg was reproducible, without any technical diculties.
Table 2 Wheat seedings' growth in composting media of dierent ages Duration
3-Weeks
6-Weeks
9-Weeks
12-Weeks
15-Weeks
Culture
Av. height (cm)
Av. height (cm)
Av. height (cm)
Av. height (cm)
Av. height (cm)
Master control Control P-1 P-2 P-3 Vv S-1 S-2
13.9 6.9 8.2 8.9 9.1 10.5 11.5 11.2
14.2 6.5 11.3 11.2 11.5 12.2 13.8 12.9
14.5 6.8 12.5 11.9 12.2 13.2 16.9 16.1
14.6 7.3 13.7 12.9 13.0 14.3 18.5 17.5
15.2 7.9 14.5 14.2 14.3 15.8 19.9 18.1
P-1 Pleurotus ostratus; P-2 Pleurotus sajar caju; P-3 Pleurotus ¯orida; Vv Volvariella volvaceae; S-1 Volvariella sp. and S-2 Volvariella sp. Bold type indicated the most ecient fungus composting eucalyptus bark.
K.R. Yadav et al. / Bioresource Technology 81 (2002) 163±165
165
Fig. 1. Histogram depicting height, biomass and chorophyll content of wheat seedlings as a function of BSC, derived from three cultures. S-1 Volvariella sp.; S-2 Volvariella sp. and Vv Volvariella volvaceae.
3.4. Properties of BSC
References
The BSC was a partially decomposed solid, organic, dark brown mass. It imparted porous texture and water holding capacity to soil, thereby promoting root rami®cation and sustained growth rate. Microscopy revealed the presence of Pseudomonas, Aspergillus, Penicillium and Bacillus in decreasing number as the major bene®cial microbes, earlier observed by others also (Davis et al., 1992; Kostov et al., 1994).
Davis, C.L., Hinch, S.A., Donkin, C.J., Gerishuizen, P., 1992. Changes in microbial population numbers during the composting of pine bark. Bioresour. Technol. 39, 85±92. Deschatelets, D.L., Yu, E.K.C., 1986. A simple pentose assay for biomass conversion studies. Appl. Microbiol. Biotechnol. 22, 379± 382. Guedes de Carvalho, R.A., Gonzales Beca, C.G., Naves, O.R., Sol Pereira, M.C., 1991. Composting of pine and eucalyptus bark. Bioresour. Technol. 38, 51±63. Jayaraman, J., 1992. Laboratory Manual in Biochemistry. Wiley Eastern Press, Bombay. Kostov, O., Petkova, G., Vancleemput, O., 1994. Microbial indicator for saw dust and bark compost stability and humi®cation processes. Bioresour. Technol. 50, 193±200. Miller, G.L., 1959. Estimation of reducing sugars by dinitrosalicylic acid. Anal. Chem. 31, 426±428. Ramamurthy, V., Sharma, R.K., Yadav, K.R., Kaur, J., Dev Vrat, V., Kothari, R.M., 1996. Volvariella treated eucalyptus saw dust stimulates wheat and onion growth. Biodegradation 7, 121±127. Ramamurthy, V., Sharma, R.K., Kothari, R.M., 1998. Microbial conversion of ligno-cellulosic wastes into soil conditioners. In: Pandey, A. (Ed.), Advances in Biotechnology. Educational Publication, New Delhi, pp. 433±438. Sharma, R.K., Yadav, K.R., Kothari, R.M., 1994. Innovative recycling of vegetable protein waste for increased productivity. Technovation 14, 31±36. Updegra, D.M., 1969. Semi-micro determination of cellulose in biological material. Anal. Biochem. 32, 424±428. World Bank Report of bark and saw dust composting, vol. 264, 1995, pp. 63±65.
4. Conclusion An optimized, simple, cost-eective and eco-friendly protocol was developed for the bioconversion of eucalyptus bark into soil conditioner. In view of its physico-chemical and microbial characteristics, it releases nutrients for rhizospheric microbes and plants for rapid growth on sustained basis. Acknowledgements The authors are grateful to Professor S.F. Patil, ViceChancellor, North Maharashtra University, Jalgaon for providing experimental facilities.