Jatropha curcas, an attractive crop for developing countries

Jatropha curcas is a hardy plant which can withstand arid environments and grow on poor wastelands typical of developing countries. Oil can be extracted from the fruit of Jatropha crops which is non-edible but can be put to use for a variety of purposes, from sustainable chemistry to energy generation and biofuel. A series of evaluations of the feasibility of promoting Jatropha energy crops, especially on marginal farm lands in the Mediterranean region, was carried out by the JatroMed Project with the participation of Italy through CREA-ING. Five years of experiments have led to the identification of the most suitable mechanization system for the harvest of these crops, optimizing yields and safeguarding the work performed by farmers

Jatropha curcas is a species of flowering plant in the spurge family native to the Central and South American tropics, Africa, India and Southeast Asia. The Jatropha evergreen shrub is traditionally used as brush for the protection of fields under crops or gardens and also to counter soil erosion and safeguard biodiversity.

The fruit of the plants is highly toxic to humans and animal but the oil which can be rendered from the seeds means their cultivation is of interest for a variety of uses which range from sustainable, or green, chemistry to bioenergy. Under the sustainable chemistry heading, Jatropha oil makes up raw materials for the production of lubricants, soap, detergents, bath oil, softeners and the like. For bioenergy purposes, this oil can be used as it is for fuel for cooking and illuminating interiors, after filtration for fuel for modified engines and, finally, after an industrial process of alkaline transesterification, for biodiesel.

Because the sturdy Jatropha plants can be cultivated in arid and hot regions such as desert areas they do not require water so they do not take over food crop lands. This characteristic means the Jatopha can be considered a valid option as a cash crop grown in these environmental conditions and move into a highly promising market segment. What has already occurred, but must be avoided, is the greed of big industrial groups improperly using lands with a potential for food crops or their shortcomings in attempting to generate very real economic fallout for lands in settings in which poverty and access to food are the primary problems to solve.  

From this point of view, operational plans must be developed for allowing the penetration of a supply chain and technologies capable of fostering the sustainability of renewable raw materials, avoiding competition with food crops and, on the other hand, stimulating synergies of the two sectors. With this in mind, the European Union JatroMed Project – Evaluation of the energy crop Jatropha curcas as a mean to promote renewable and sustainable energy for the Mediterranean region – was created with the Agrarian Engineering Unit of the Council for agricultural research and analyses of the agrarian economy, CREA-ING, joining as the Italian partner. The project, coming to a close after five years of work, brought together five Mediterranean countries and the same number of research institutes: Greece (Agricultural University of Athens - AUA, coordinator of the project), Italy (CREA-ING), Egypt (City for Scientific Research and Technology Applications -MuCSAT), Morocco (Centre de Developpement de la Region de Tensift - CDRT), and Algeria (Centre de Développement des Energies Renouvelables - CDER).

Speaking at a workshop entitled Mechanization of Jatropha curcas Harvest held for reporting on the project, a member of the CREA-ING team of collaborators, Luigi Pari, said the purpose of JatroMed has been to improve the social-economic conditions of rural communities in the partner countries by meeting the needs of energy self-sufficiency with the cultivation of Jatropha curcas drawing on techniques and machinery suitable for the various conditions.

On the basis of experiments carried out in Italy, it has been found that Jatropha cannot be cultivated in the country, not even in the southern regions, due to climatic conditions. The contribution Italy can provide for the cultivation of this crop consists mainly of the transfer of know-how acquired in a number of studies on energy crops conducted over the years by the nation’s leading research institutes and the capability of Italian mechanization industries to come up with technologies making these cultivations financial feasible in more suitable countries by entering the market now held by only a few manufacturers, most of them abroad.

On the understanding that Jatropha yields vary greatly per unit of land area planted, in relation to the availability of water and soil fertility (see Table  page 66), agronomic experiments show that there is substantial room for improving productivity through the selection of the cultivar and crop protocols and reducing harvesting costs by using innovative machinery and optimizing the logistics of the operation. In light of these considerations, finding the criteria of efficiency for the harvest of the fruit with specific machinery has undoubtedly been the pivotal factor for researchers involved in the project and committed to exploiting the advantages of this resource.

Growing interest in this crop for energy use on an industrial scale could lead some enterprises to devise   strongly automated harvesting systems based on total mechanization. Taking this theoretical line could appear as an ideal solution for improving the efficiency of the process and working conditions for operators while reducing harvesting costs. However, considering that this crop should become established in developing countries as an opportunity for generating income for the local population, the introduction of full mechanization for harvesting creates other criteria. These are linked to the high cost of acquisition and the maintenance of machinery and the resulting reduction in the workforce needed leading to unemployment and instability. For this reason, the approach recommended by CREA-ING is semi-mechanical harvesting which, in this setting, could be seen as a sound compromise between manual labor and full mechanization (see box page 68). To make best use of the results of the JatroMed Project, the stakeholders and local communities identified as the final beneficiaries of the work completed were actively involved by having them visit the demonstration fields to witness work and gain familiarity with the best crop techniques singled out for the various phases of the production process.

Systems for harvesting Jatropha fruit

Manual harvesting

The most widespread system for harvesting Jatropha fruit is manual performed with the aid of a pole for reaching the highest parts of the plants with an average height of 3 to 5 meters and, in favorable conditions, up to 8 to 10 meters. The daily harvest can be up to 40-70 kg per person in a well managed plot whereas lower yields can be down to 20-30 kg per person per day. This harvesting procedure is complicated and tiring and carries a heavy impact on the cost of Jatropha oil production. Harvesting Jatropha and the extraction of seeds from the fruit is work generally performed by women but more technical operations involving agronomic practices, for example, or the use of machinery for extracting oil, are done by men. Manual harvests can be considered a valid method for small plots for highly selective collection whereas the prospect of earmarking the product for energy use requires greater efficiency in the field and reducing the time needed for work and less labor for workers.

 

Fully mechanized harvesting

There are numerous advantages with mechanical harvesting (greater efficiency, reduced fatigue for the workers, lower production costs, etc.). The high cost of these machines, from $150,000 to $200,000, means serious prior cost-benefits analyses carried out with consideration for the extension of the land area involved, the planting layout and the social-economic characteristics of the territory. At present, various prototypes of machinery are in use, such as: the trunk shaker – developed by an Israeli company – which produces vibrations sufficient to selectively bring down mature fruit; specially modified grape harvesting machine models – designed and marketed by a number of manufacturers – equipped with horizontal agitation;  a self-propelled model based on a coffee harvester (Korvan 9240), developed in the United States by Oxbo Int.Corp. The machine is 3.5 meters wide and weighs 6,000 kg with an operational capacity of  0.15-0.6 ha/hour at 1-3 km/hour and fuel consumption of 9 to 12 l/hour; a Joonas model harvester from the Finnish company Oy Rakennustempo Ltd. According to test results capacity in the field is 0,5-0,8 ha/hour which corresponds to work of 100-150 manual laborers. The U.S. Jatropha Onda Harvester BEI capable of performing selective harvesting by picking ripe fruit and leaving immature fruit in place for harvesting when ripe. Manufacturer’s specifications put efficiency at about 1 ha/hour and fuel consumption at some 7.5 l/hour.

 

Semi-mechanical harvesting

A good compromise between manual harvesting and integral mechanization is recourse to specialized machines which facilitate the task. There is an ample range of devices for taking this approach, automatic shakers and beaters in various shapes and with various functions already in use in the Mediterranean region for the collection of fruit of similar dimensions such as olives, nuts, apricot and cherries. These semi-mechanical systems detach fruit by shaking branches or work operating directly on the fruit. They can be powered by an electric motor, a gasoline engine or a suction system. Their costs for purchase and maintenance is less, they are easy to use and they ensure a substantial improvement in capacity compared to fully manual techniques. The best devices have been identified through studies on frequency and breadth of vibrations or the structure and rigidity of combs and flails for collecting only ripe fruit and leaving unripe fruit on the plant to mature for harvesting later.