Laura D’Andrea1*, Giuseppe De Mastro2, Angelo Domenico Palumbo1
1
Consiglio per la Ricerca in Agricoltura e l’analisi dell’economia agraria (CRA) - Unità di Ricerca per i Sistemi Colturali degli Ambienti caldo-aridi (SCA), via Celso Ulpiani, 5 - Bari, Italy
2 Dipartimento di Scienze Agro-Ambientali e Territoriali (Di.S.A.A.T.), Università degli Studi di Bari ‘Aldo Moro’, via Amendola 165/A - Bari, Italy
Abstract
Cardoon (Cynara cardunculus L. var. altilis DC.), is a perennial herbaceous species native to the Mediterranean region. It is used for a multitude of industrial applications, among which the lignocellulosic biomass production. Raw material produces second generation bioethanol after a pre-treatment. The experimental field was carried out in Southern Italy for two years, aiming to evaluate the biomass production and to analyze the chemical composition of biomass. The harvest was carried out in August when the plants were completely dry. The content of cellulose, hemicellulose and lignin were determined by Van Soest method. Subsequently, the ethanol content and bioethanol yield were calculated. The values obtained were similar to those of cardoon cultivated in other field experiments as well as for other species used in bioethanol chain. The results of the research encourage further studies on cardoon as a raw material source of second generation biofuels.
Keywords: cardoon, biomass yield, ethanol content
Parole chiave: cardo, resa di biomassa, contenuto di etanolo
Introduction
The cultivation of energy crops plays a key role as a source of renewable energy, which has been confirmed by the Directive 2009/28/EC on National Renewable Energy Action Plans.
Among energy crops, perennial species seem to be more promising of annual plants in consideration of the their more favourable benefits.
Among perennial plants the cardoon (Cynara cardunculus var. altilis DC., Asteraceae family, Wiklund, 1992) represents a crop with low energy input. This species is perennial with an annual development cycle in which the seed reproduction is completed by the summer (Fernandez
et al., 2006). It has high growth and biomass production,
fully adapted to Mediterranean climate conditions. The typical characteristics of semi-arid Mediterranean climate are the low annual rainfall regime as well as its irregular distribution and the hot dry summer. The way in which cardoon overcomes this unfavorable season is the so-called “drought-escape strategy”.
Cardoon can be cultivated as an energy crop for a multitude of industrial applications (Maccarone et al., 1999; Foti et
al., 1999; Piscioneri et al., 2000; Curt et al., 2002;
Gominho et al., 2001; Mantineo M., et al., 2009) among which that for lignocellulosic chain. The whole above- ground lignocellulosic biomass can be directly used for heating or for electric power generation or can produce second generation bioethanol after a pre-treatment.
The aim of this study was to evaluate the biomass production for bioethanol and to analyze the chemical composition of biomass.
Materials and Methods
Field experiment was carried out at the experimental farm of CRA-SCA located in Rutigliano (Bari, Southern Italy), (41°01’N; 17°01’E; 147 m a.s.l.) for two cropping seasons (2009-2010 and 2010-2011).
The soil was a clay soil classified as Rodoxeralph (USDA). The meteorological data were measured by a climatological station in the experimental farm (Tab. 1).
Seeds of a cultivar from Polytechnic University of Madrid (Spain) were sown on October 2009 with a plant density of 30,000 plants ha-1 with inter-row spacing of 1.2 m. Experimental design was a randomised block with four replications and each plot size was 2,250 m2. Tillage was carried out in the autumn of 2009 by medium-depth ploughing (0.3 m). Seed bed preparation was shaped by a pass with a disk harrow. Pre-plant fertiliser was distributed at a rate of 100 kg P2O5 ha-1.
The above-ground biomass was harvested on 18th and 10th, August 2010 and 2011 respectively, when the plants were completely dry (about 70-80% of dry matter) and than was placing in a thermoventilated oven at 65 °C until constant weight.
Chemical analysis: neutral detergent fiber (NDF) was determined without sodium sulfite and with a heat-stable amylase; acid detergent fiber (ADF) and acid detergent lignin (ADL) were determined by sequential analysis of the residual NDF; hemicellulose was calculated as NDF–ADF, and cellulose as ADF–ADL (Van Soest et al., 1991).
Subsequently, the ethanol content was calculated multiplying the percentages of cellulose and hemicellulose with correction coefficients and, furthermore, bioethanol yield was calculated (bioethanol content per biomass yield).
Tab. 1 - Meteorological data in two cropping seasons (2009-2010 and 2010-2011) compared to long-term (31 years).
Tab. 1 – Dati metereologici nelle due stagioni colturali (2009-2010 and 2010-2011) confrontati con i dati di lungo periodo (31 anni).
Tab. 2 - Chemical analysis of dry above-ground biomass of cardoon in the first and second year of the experimental trial.
Tab. 2 - Analisi chimiche della biomassa areica secca del cardo nel primo e secondo anno della prova sperimentale.
Fig. 1 - Ethanol content and yield in the dry above-ground biomass of cardoon in the first and second year of the experimental trial.
Fig. 1 - Contenuto e resa di etanolo nella biomassa areica secca del cardo nel primo e secondo anno della prova sperimentale.
Results and Discussion
The meteorological data (Tab. 1) showed that: minimum temperatures were higher when compared to long-term data and winter months (December, January, and February) were coldest; maximum temperatures were higher in July and August and in general were higher when compared to long- term data; rainfall was higher in the first (604.6mm) and second (676.3mm) year of cropping season when compared to average of long-term (575.8mm). The wettest month was October and the driest month was August.
The dry above-ground biomass yield was 8.7 and 15.6 t ha-1 in the first and second year (data not shown). These data are similar at other research in open field (Maccarone et al., 1999; Foti et al., 1999; Piscioneri et al., 2000; Curt et al., 2002; Mantineo et al., 2009).
The values of chemical analysis (Tab. 2), mean of two years, were similar to those of cardoon cultivated in other field experiments in Europe (Fernandez et al., 2006) as well as for other species used in bioethanol chain (Godin et al., 2010).
Ethanol content was not different between years, but ethanol yield was directly proportional to the biomass yield (Fig. 1).
Conclusion
The results of the this research encourage further studies on cardoon as a raw material source of second generation biofuels.
Aknowledgements
This work has been supported by Italian Ministry of Agriculture, Food and Forestry Policies (MiPAAF) under BIOSEA project (Ottimizzazione delle filiere bio-energetiche esistenti per una sostenibilità economica e ambientale) (D.M. 16916/7303/10, 23 July 2010).
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0 100 200 300 400 2010 2011 (K g e th a n o l t -1 ) b a 0 1000 2000 3000 4000 5000 2010 2011 (K g e th a no l ha -1 ) Month 2009- 2010 2010- 2011 long- term 2009- 2010 2010- 2011 long- term 2009- 2010 2010- 2011 long- term September 16.2 14.7 15.8 26.3 25.1 25.9 44.8 51.4 56.4 October 10.5 11.2 12.9 19.6 20.0 21.9 149.8 222.8 48.4 November 7.8 9.6 8.6 17.4 18.6 16.5 34.6 68.2 71.9 December 6.3 5.2 5.7 14.2 13.1 12.9 71.8 41.5 69.2 January 4.5 3.8 4.5 11.5 11.6 12.0 32.3 33.8 61.4 February 5.0 3.3 4.3 13.4 12.9 12.1 38.4 35.2 57.7 March 5.6 6.6 6.1 15.3 14.7 15.1 55.8 102.6 56.3 April 8.2 7.9 8.3 18.8 19.1 18.0 47.0 19.6 40.7 May 12.7 11.6 12.4 23.2 22.8 23.0 73.3 36.6 36.0 June 16.0 18.0 16.0 27.0 31.5 27.3 25.6 30.6 29.1 July 19.7 20.6 18.3 30.4 35.3 29.8 18.0 34.0 22.0 August 22.3 20.8 18.5 32.6 36.4 29.8 13.2 0.0 26.7 Average/ Total 604.6 676.3 575.8
Min Temp (°C) Max Temp (°C) Rainfall (mm)
11.2 11.1 11.0 20.8 21.8 20.3
Chemical analysis Mean Dev.St. Neutral detergent fiber NDF 72.3 1.3
Acid detergent fiber ADF 48.8 1.5
Acid detergent lignin ADL 7.3 0.9
Cellulose ADF-ADL 41.4 1.5