The impending climate change crisis has stimulated enormous interest in the development of biofuel globally. The supporters of biofuel hail that it is naturally carbon-neutral whereas the critiques argue that the large-scale plantations and production of biofuel based on Jatropha can not only strain agricultural resources but also threaten future food security. India's subsistence farmers are often faced with challenges and constraints of poverty. Foremost among the challenges are the marginal environmental conditions for agriculture often influenced by erratic rainfall, drought, poor soil quality, and unreliable irrigation water supply. In this article, we have presented a case study on the potential to use nonedible seeds from naturally occurring tree species, Calophyllum inophyllum to meet the increasing demand for biofuel production in India.
Biofuel is being promoted widely as a solution to rising fuel prices, growing energy demands, and to cut greenhouse gases (Liao et al., 2012). Therefore, governments from around the world are increasingly promoting biofuel with a priority to plant Jatropha (Jatropha curcas) (Agoramoorthy, 2009). The jatropha-based biofuel was originally developed in Central America. The plant, which produces oilseeds, grows well even in arid landscape. However, scientific debates continue on the problems and failures involving jatropha as a global biofuel savior (Kant & Wu, 2011). In Tamil Nadu state of south India for example, the jatropha cultivation has not only failed to reduce poverty but also created conflict among various social classes (Ariza-Montobbio & Lele, 2010). In spite of this, India has launched an ambitious plan to produce high-yielding jatropha and the land available for cultivation is estimated at 13.4 million ha with a yield potential of 15 million tons annually from oil (Pramanik & Tripathi, 2005). Therefore, India needs more investment to expand infrastructure, seed collection, oil extraction, storage, and marketing to meet the biofuel demand for the 5% blending.
As a matter of fact, the Government of India has approved a national policy on the development of biofuel with a target to implement 20% ethanol-blended petrol/diesel across the country by 2017 (Business Standard, 2008). This new policy will remove all federal taxes on bio-diesel while ensuring a uniform 4% sales tax on the product. The new bio-fuel strategy will ultimately enforce a 5% ethanol-blending in gasoline as mandatory. Bio-diesel production will be taken up from nonedible oil seeds in waste, degraded, and marginal lands focusing mainly on the indigenous feedstock. However, ecologists worry that the headlong rush into growing biofuel crops using Jatropha will bring its own environmental, social, and economic problems if appropriate preventative measures are overlooked in rural areas (Kant & Wu, 2011; Liao et al., 2012). For instance, 68% of India's workforce relies on farming despite the decrease of agriculture contribution to GDP from 38% in 1975 to 19% in 2007. India requires 210 million tons of grain to feed its people, but produced only 200 million tons in 2007. The cultivable land, which relies mainly on monsoon, has remained stagnant at 120 million ha (Agoramoorthy, 2009). In this murky situation, would it be worthwhile for India to invest millions of dollars to promote Jatropha cultivations?
People across India have been using the nonedible oil extracted from various commonly occurring native tree species for household uses for centuries, and Calophyllum inophyllum is one among the most useful trees with a great potential for biofuel extraction (Venkanna & Reddy, 2009). The generic name Calophyllum originates from Greek, meaning ‘beautiful leaf’. It belongs to the family Clusiaceae (Guttiferae). In English, it is known as Alexandrian Laurel; it also has various other vernacular names from several tropical countries. In the ancient Tamil literature of south India for example, it is referred as ‘Pinnai’, whereas in Marathi language as Undi and in Hindi as Sultan Champa. This oil seed bearing tree often grows along India's vast coastline and its adjoining lowland forest areas. This mangrove associate occurs in several countries across Asia. It is also found inland on sandy soils up to few miles from the rivers' mouth. This attractive tree is widely preferred for display in many countries due to its decorative leaves, aromatic flowers and wide crown. This adaptable tree can grow in clayish, sandy, and degraded soil and reaches up to 35 m height (Cowen, 1984).
The biodiesel obtained by means of a 3-stage transesterification process of acid esterification, alkali transesterification, and post treatment found the oil extracted from Calophyllum inophyllum ideal for the use in direct injection diesel engines (Venkanna & Reddy, 2009; Onga et al., 2011). However, quantitative data on the occurrence, density, status, seed bearing capacity and sustainable harvesting of seeds for biofuel processing are lacking in the literature. This case study presents data on the availability of the oil rich seeds of the flowering plant, C. inophyllum, which has excellent potential to meet India's future demand for biofuel production and sustainable management.
Materials and methods
In the Konkan region of Maharashtra (India), Calophyllum inophyllum occurs along the coast where local communities have a tradition of extracting oil from the seeds (Sharma, 1996). The oil is still being used for painting fishing boats to prevent deterioration of wood and metal component. The oil extraction forms livelihood for the local ‘teli’ community. However, due to modernization, the traditional oil extraction business in rural areas is declining whereas the demand for its hard wood in the construction of boats and houses has been increasing. So, people have started to cut mature trees for sale instead of sustainably using the seeds for oil extraction. The natural oil is cheaper than most commercial oil so there is still a local demand.
Surveys were conducted to assess the population status of fruit-bearing adult trees of Calophyllum inophyllum occurring in Ratnagiri and Sindhudurg districts of Maharashtra State, India. Eight major sampling locations covering 72 villages along estuaries were systematically surveyed to record the occurrence of trees. Straight line transects of 1 km were randomly laid along the seashore, estuaries, rivers, agriculture lands, and forest areas with an interval of 2–3 km and a total count of all trees belonging to C. inophyllum was carried out. The measurements of girth at breast height (GBH), height, and habitat type were recorded (Colinvaus, 1993). For each mature tree, the average number of primary, secondary, tertiary and quaternary branches as well as oil bearing fruits/seeds were counted. Besides, data on seed dispersal, oil extraction, and cutting of matured trees for trade were also recorded.
The Global Positioning System (GPS) waypoints were noted for all sampling locations. In addition, the status of tress (lopped, coppiced, or normal) was recorded. The percentage of clipped trees was calculated as the number of clipped trees divided by total number of trees in each location. The percentage of fruits was calculated as the total number of fruits in each location divided by the total number of fruit production. Trees were counted individually and within the clump whereas one tree was selected to record its GBH, height, and number of fruits. Therefore, 652 tree samples were measured from 1420 trees in eight locations out of the survey of 72 villages. However, only 504 trees with fruit production more than 500 fruits per tree were used for later analysis. The total fruit production in each location was the accumulated number of fruits estimated from those trees of Calophyllum inophyllum in the given location.
Statistical Analysis System software was used for statistical analyses (SAS Release 8.1, 2000; SAS Institute Inc., Cary, NC, USA). All mean values are presented as ± 1 standard deviation. Wilcoxon rank tests (nonparametric) were used to compare the differences in GBH, height, and number of fruits between clipped and unclipped trees. Various general linear models were used to test: (i) the effects of location, height and GBH on fruit production; (ii) the effect of locations on dependent variable (GBH, height, or fruit production) by using Duncan's multiple range tests to calculate differences within eight locations for the dependent variable (GBH, height, or fruit production), and (iii) the effects of GBH and height on fruit productions in clipped or unclipped trees. Then, the best linear regression equation was selected to estimate the number of fruits (Y) according to GBH or/and height of clipped or unclipped trees (SAS Institute).
The highest number of trees was found in Madban (305), followed by Ambolgad (299) and the lowest one was in Palye-Nanar (Fig. 1). The highest percentage of clipped trees was 54.0% occurred in Holi followed by 30.3% in Vetye and 20.8% in Jaitapur. The total fruit production was highest in Ambolgad accounting for 28.5% of the total fruit production from eight locations (Fig. 1); Ambolgad was the only location without any clipped trees. The second highest fruit production was found in Danda-Ansure (22.8%), and it was followed by Madban (22.8%, Fig. 1). The total number of C. inophyllum in the above three locations accounted for 60.0% of total trees (852/1420) with 69.7% of total fruit production of 504 trees with fruits more than 500 per trees. The location, height, and GBH significantly influenced the number of fruits (F9,494 = 28.2, P < 0.001, R2 = 0.34). The highest number of fruits per tree was 3954.0 (± 2853.6, n = 10, Table 1, Duncan's multiple range test) in Vetye. Similarly, the highest GBH was also found in the same location (164.0 ± 117.9 cm). The lowest average number of fruits per tree was 1857.8 (± 1564.3, n = 18) in Palye-Nanar whereas the average tree height was tallest in Palye-Nanar (11.3 ± 1.9 m, n = 18) and it was significantly higher than the other seven locations (P < 0.001, Table 1). The lowest GBH of trees was found in Jaitapur 80.2 cm (± 16.2) and the average number of fruits per tree was the second lowest at 1912.0 (± 1213.6, n = 15, Table 1).
Table 1. Total sample size, mean, and standard deviation (SD) of girth at breast high (GBH), height, and number of fruits of C. inophyllum harvested in eight locations in Maharashtra State, India
a, b, c, d were from Duncan's multiple range tests. Different letters indicated significant differences existed (P < 0.05) in GBH, height or fruit production of eight locations.
88.9b ± 26.2
11.3a ± 1.9
1857.8d ± 1564.3
82.9b ± 26.2
9.3bc ± 2.1
2414.6bcd ± 1608.4
106.1b ± 42.9
9.6b ± 1.9
3402.1ab ± 1839.9
86.4b ± 20.4
8.1c ± 0.8
2085.5cd ± 1409.3
80.2b ± 16.2
8.1c ± 0.8
1912.0d ± 1213.6
142.0a ± 66.0
8.9bc ± 1.6
3137.2ab ± 2186.7
99.6b ± 31.3
8.6bc ± 1.4
3020.0abc ± 1585.8
164.0a ± 117.9
9.2bc ± 1.4
3954.0a ± 2853.6
97.1 ± 43.4
9.4 ± 2.0
2812.6 ± 1819.7
The number of fruits, GBH, and height were significantly correlated to each other either in the clipped or unclipped group (P < 0.01, Pearson correlation). The GBH of clipped trees was 121.4 cm (± 72.7, n = 58), which is significantly larger than the unclipped trees (93.9 cm ± 37.0, n = 446, P < 0.01, Wilcoxon rank test). However, the average height of these two groups were similar (Wilcoxon rank test P > 0.95, 9.41 m ± 2.25 vs. 9.36 m ± 1.93). The average number of fruits in the clipped trees was 2858.6 ± 1811.2 and it was slightly higher than those of the unclipped trees (2806.6 ± 1822.7) with no significant difference (Wilcoxon rank test, P > 0.74). The number of fruits of unclipped trees were significantly influenced by the trees' GBH (F1,443 = 124.0, P < 0.001) and height (F1,443 = 28.7, P < 0.001). Therefore, the fruit production of an unclipped tree can be estimated as: number of fruits (Y) = −1380.9 + 214.0 × (Height) + 23.2 × GBH (F2,443 = 130.4, P < 0.001, R2 = 0.37). On the other hand, in clipped trees, the trees' GBH had significant effect on fruit production (F1,55 = 6.53, P < 0.02), but height did not have any effect (F1,55 = 0.13, P > 0.72). Therefore, the fruit production of a clipped tree was estimated as: number of fruits (Y)= 1821.9 + 8.54 × GBH (F1,56 = 7.4, P < 0.01, R2 = 0.12).
Due to the decline in the traditional oil extraction business in Ratnagiri and Sindhudurg districts of Maharashtra State of India, the wood cutting pressure has increased rapidly therefore immediate intervention is needed to save these trees from local extinction. For example, in Danda-Ansur location, only nine oil extraction machines were recorded of which only three were in working condition. Although the community elders have showed interest to continue their oil business, they often suffer from low income from oil extraction. On an average, a person can earn up to USD 2 per day by working in nearby stone mines and the earning from oil extraction may not reach even a dollar. Those who collect oil seeds in forest areas get only less than USD 1 per day. Besides, the owners of oil extracting factories worry about the increasing transport costs and decreasing profit margins leading to loss of interest in the traditional oil extraction business. That's why the local communities have been forced to start mango, cashew, and coconut palm plantations replacing Calophyllum inophyllum.
Likewise, the Maharashtra State Forest Department has been encouraging farmers to plant the exotic Casurina plantation to protect the ecologically sensitive coastal areas. Therefore, the social forestry scheme also threatens the survival of Calophyllum inophyllum that otherwise occupy about 70% of the coastal landscape – they naturally protect the coast from erosion and saline incursion. These highly adaptable trees survive well along the coastal edges of swamps. However, the coastal areas are increasingly being converted artificially by using stones and concrete materials in the name of coastal management so the trees along with the swamps are becoming locally extinct. Unless the state and central government agencies and corporate sectors realize the biofuel potential of Calophyllum inophyllum along the vast Indian coast lines, the looming extinction crisis facing these amazing oil seed bearing trees cannot be solved.
A total of 1420 trees belong to Calophyllum inophyllum were surveyed during this study and these trees could yield up to 7647.37 kg of dry seeds. Besides, each tree has the potential to produce a maximum of 12 liters (average 2.78 liters) of non-edible oil per year. This tree flowers year around with two distinct flowering peaks (late spring/autumn) and it often bears fruits throughout the year. Hence, fruits can be harvested at least twice if there is a viable biofuel market created in coastal areas. Data are lacking on the occurrence of exact number of adult C. inophyllum trees in India. Nevertheless, by using data from this study, we can infer a minimum of 100 000 adult trees across coastal India with an oil yield potential of 1.2 million liters per year.
When edible oils price go high in India, people are forced to source for nonedible oils that are needed for domestic and cultural uses. As a result, the non-edible oil sector requires over 15 million tons of seeds harvested and processed in villages as cottage-industries (Agoramoorthy, 2009). Therefore, there is a necessity to revive this traditional harvesting of locally available oil seeds. A decade ago, Calophyllum inophyllum trees were common along India's vast coastline stretching over 7517 km, but they are fast disappearing as over 20% of India's total 1.21 billion inhabitants live along the ecologically fragile sea coast. As a result, C. inophyllum has been included in the IUCN Red List of Threatened Species in the category lower risk/least concern (IUCN, 2012). Furthermore, C. inophyllum, other nonedible oil seed producing trees namely Azadirachta indica, Pongamia pinnata, Madhuca indica, and Shorea robusta are found throughout India, but they are not yet fully utilized for biofuel (Mohanty et al., 2009). Therefore, it is imperative for the government, corporate, and nongovernment sectors to develop systematic collection and processing of these often ignored seeds for biofuel production. If seeds are collected at the grassroots level, it will initiate a supply chain that can ultimately link to national level. The remains of the seeds can be used by the farmers to feed their household biogas plants and as natural fertilizer to promote sustainable development (Agoramoorthy & Hsu, 2008).
India is the sixth largest consumer of energy in the world and its energy demand is growing at an annual rate of 4.8%. The demand for the refined products may rise at even a higher rate, and for example, the demand for diesel will increase at the rate of 5.8% annually reaching 65 m tones by 2030 (GOI, 2003). India's National Biofuel Policy highlights that the bio-diesel will target the local plants that harbor higher contents of nonedible oil seeds produced in the nonarable lands. Prime agricultural lands will be not be targeted for biofuel crop production. To provide farmers with fair prices, the Biofuel Steering Committee will set a minimum support price for biofuel oil seeds with the provision of periodic revisions. Nevertheless, farmers do not get support price for biofuel seed collection at present and they also lack long-term purchase contracts from companies (Govinda & Shrestha, 2011). So the government and biofuel companies must encourage farmers to protect native trees of biofuel potential to enhance propagation, protection, collection, extraction, and refinement of biofuel. Capacity building, financial assistance, bank loans, and insurances for trees/seeds are essential and then only farmers can improve their knowledge on cultivation/collection of seeds as well as protecting trees from loses against natural disasters, such as droughts, cyclones, tsunamis, and floods.
According to the Planning Commission of India, the biofuel demand is estimated at 5.0% and 4.5%, respectively, in the twelfth plan (2011–12 to 2016–17; GOI, 2003). India depends heavily on the domestic sugarcane molasses and sometimes the production drops due to unpredictable monsoon and drought (Nigam & Agrawal, 2004). Therefore, India can ideally source for alternative biofuel locally. The seeds and nuts of over 100 species of wild or cultivated plants in India are known to bear oil in commercially extractable quantity (Hegde & Damodaram, 2005). If they are harvested to extract oil systematically across rural areas, it may eradicate India's addiction to jatropha while comfortably meeting the escalating local demand for biofuel.
The senior author extends sincere thanks to Archana Godbole, director of the Applied Environmental Research Foundation, for the generous hospitality. Constructive suggestions provided by Pratiksha Patel greatly enhanced the quality of presentation of this article, for which the authors are grateful.