Herbaceous Oil Crops, a Review on Mechanical Harvesting State of the Art

Abstract

The sustainable production of renewable energy is a key topic on the European community’s agenda in the next decades. The use of residuals from agriculture could not be enough to meet the growing demand for energy, and the contribution of vegetable oil to biodiesel production may be important. Moreover, vegetable oil can surrogate petroleum products in many cases, as in cosmetics, biopolymers, or lubricants production. However, the cultivation of oil crops for the mere production of industrial oil would arise concerns on competition for land use between food and non-food crops. Additionally, the economic sustainability is not always guaranteed, since the mechanical harvesting, in some cases, is still far from acceptable. Therefore, it is difficult to plan the future strategy on bioproducts production from oil crops if the actual feasibility to harvest the seeds is still almost unknown. With the present review, the authors aim to provide a comprehensive overview on the state of the art of mechanical harvesting in seven herbaceous oil crops, namely: sunflower (Heliantus annuus L.), canola (Brassica napus L.), cardoon (Cynara cardunculus L.), camelina (Camelina sativa (L.) Crantz), safflower (Carthamus tinctorius L.), crambe (Crambe abyssinica R. E. Fr.), and castor bean (Ricinus communis L.). The review underlines that the mechanical harvesting of sunflower, canola and cardoon seeds is performed relying on specific devices that perform effectively with a minimum seed loss. Crambe and safflower seeds can be harvested through a combine harvester equipped with a header for cereals. On the other hand, camelina and castor crops still lack the reliable implementation on combine harvesters. Some attempts have been performed to harvest camelina and castor while using a cereal header and a maize header, respectively, but the actual effectiveness of both strategies is still unknown.

Evaluating the Suitability of a Combine Harvester Equipped with the Sunflower Header to Harvest Cardoon Seeds: A Case Study in Central Italy

“…According to our findings, a similar result can be obtained without using the specific header. In fact, only 3.2% w/w of the seed loss was found and this is consistent with the findings reported in similar studies dealing with the mechanical harvesting of other oil seeds, namely: 0.97-2.76% w/w in canola (Brassica napus L.) [54,55], about 3% w/w in safflower (Carthamus tinctorius L.) [26] and crambe (Crambe cabyssinica Hochst) [56], and 2% w/w in sunflower [57], although reducible to less than 1% w/w if particular adjustments are applied [58,59]. Nevertheless, it is dutiful to underline that the specific cardoon header described by Pari et al was specifically developed to prevent the subsequent use of a shredder to manage the left aboveground biomass [28,30].…”

“…While, the harvest of the aboveground biomass takes place in the summer, using different machines according to the purpose of cultivation, moisture content, and the available fleet at the farm. The whole biomass can be harvested using a forage harvester or biomass harvester-baler [13], while seeds have to be harvested using a combine harvester [26]. The first attempts of Cynara seeds mechanical harvesting are dated back to the 90s, but machines could not cope with the high quantity of pappi released by the capitula during harvesting.…”

Assessing the Camelina (Camelina sativa (L.) Crantz) Seed Harvesting Using a Combine Harvester: A Case-Study on the Assessment of Work Performance and Seed Loss

“…According to this, costs of harvesting and logistic have to be evaluated, in order to make camelina cultivation fully sustainable and give support in the decision-making process to farmers and other stakeholders. Currently, mechanical harvesting of camelina is mainly carried out by using a combine harvester equipped with wheat header [33], only few experiences on cutting and swathing are reported [34]. However, seed loss can be very high, as a consequence of the tiny dimension of the seeds which are very small and light in weight [35,36] moreover, presence of weeds can further increase seed loss amount.…”

Environmental and Economic Assessment of Castor Oil Supply Chain: A Case Study

“…On the contrary, castor mechanized harvesting needs to be improved due to the major losses, which can be up to 50% as evidenced by [48]. So far, only one machine manufacturer has started the first harvesting tests using a specific castor header, which would be able to reduce losses to 5% [48], and Zhao et al [49] reported the possibility to harvest the capsules using a vibrating system instead of a cutting bar [49]. In the present study, losses were not considered given the uncertainty of the data to be scientifically verified in specific tests.…”