Optimization of hemp seeds (Canapa Sativa L.) oil mechanical extraction

Abstract View references (7) Mechanical harvesting of hemp seeds is performed using machines developed for other grain crops in order to allow an easier insertion of hemp cultivation into consolidated production area trying to avoid further purchase of complex and expensive machinery on the territory. On the other hand, it involves the use of machines with low harvesting efficiency because the hemp plants are considerably different from the cereal grain plant having a biomass production 2-3 times bigger than grain in weight. However, hemp seed is harvested when the seed begin to scatter. All these factors combined, lead to a complex setting of the combine harvester. In this paper, harvesting tests were performed in order to evaluate the efficiency of mechanical harvesting of hemp seeds with conventional combine harvester with cereal head, some harvest tests were carried out by varying only the machine setting without significant modifications of the machine. The experimental design included the division of the field into 4 plots, cultivated with a seeding density D1 (60 pt / m2) and D2 (30 pt / m2). Only two plots received foliar fertilization. Each plot has been divided sub-parcels collected with two working speeds of the machine: V1 (3 kmh-1) and V2 (5 kmh-1). The combination of plots configuration provided 8 experimental. The total seed yield per m2 has been obtained handpicking the seeds in experimental plots divided by agronomic pre-treatments and then cleaned. The harvest efficiency has been calculated comparing the total seed yield with the mechanical seed harvesting using different settings of combine harvester. This work showed an average harvesting efficiency of 68%. Higher efficiency percentage has been obtained on plots with 60 plants/m2 density and harvested at V1 speed. This experience has highlighted some limitations due to the general use of non-specific hemp solutions for harvest, but this result can be explained with different cultivation techniques of hemp. © 2018 ETA-Florence Renewable Energies