Mechanized olive harvesting. High performance and gentle processing
Increasingly advanced machines have now broken new ground for highly productive and product-friendly harvesting. Synergy with harvesters greatly facilitates the development of technology
The favorable vocation of the territory and the high appreciation of the population has led to olive growing in Italy becoming one of the most significant agricultural productions, which is divided into table olives, oil and various by-products. Nevertheless, olive (and consequently oil) production has declined over the past 30 years to half, from about 650,000 t in the 1991-92 crop year to less than 320,000 in 2021-22.
Planting distances and forms of plant cultivations
Planting distances are highly variable, basically in relation to the age of the plants. Centuries-old olive groves in central and southern Italy are still active, with very wide planting distances and definitely non-intensive production. For some time now, however, super-intensive forms of cultivation have been introduced, with olive groves organized in rows and compactly sized trees, all to the advantage of efficient mechanization, including harvesting. Whereas in semi-intensive cultivation, the plants have variable distances between 5 and 10 m between rows and on the row, at the super-intensive level, there are only 3-4 m between rows and 1-1.5 m between plants on the row.
That historical method is still common in the most inaccessible areas. It involves laying sheets/nets on the ground to intercept the product. Shakers, either manual or motorized, are used to facilitate the fall of the olives. The terminal tool is similar in the two cases and consists of a rake, whose metal fingers are run along the foliage of the plants so as to "comb" the foliage. Models with a motor ensure the rake vibrates for more effective detaching action. The sheets are then brought together to concentrate the olives and place them in crates for transfer to the farm.
... and the mechanized harvesting
In addition to significantly reducing the harvesting time, it prevents the olives from remaining on the ground for a long time; this is something that could affect the quality of the oil. Harvesting solutions differ with respect to the type of planting: in semi-intensive ones, shaking units are adopted, attached to the front of the tractor (or similar self-propelled vehicles), hydraulically operated with an often self-contained system powered by a pump moved by the tractor's power take-off. The equipment employs a large double-jawed " gripper," with rubber-coated ends so as not to damage the plant, which grabs the trunk (or large branches) of the plants and makes them vibrate, to cause the olives to fall, which are then intercepted by an inverted umbrella cloth, slid previously around the trunk of the plant. Finally, the olives are conveyed into two small containers, the contents of which are periodically poured into the boxes. Alternatively, the previously described solution of ground sheets is adopted.
Harvesting in super-intensive plants
Re-purposed grape harvesters are used, which - in the self-propelled version - operate as multifunctional tool carriers. Trailed hydraulically driven models, conversely, are connected to the tractor hitch and work in a lateral-rear position. Although lower in productivity, the latter limit surface soil compaction, both because of their lower mass and because the tracks left by the wheels are offset from those of the tractor tires, thus producing less localized ground pressure. Self-propelled models operate more easily on steeply sloping slopes: they are self-leveling and are easier to drive, being based on a monolithic structure. The leveling function of the machine body is entrusted to 4 hydraulic cylinders (one per wheel), which, together with the central hinging of the harvesting module, ensure effective vertical alignment of the harvesting head with the canopies, especially when driving in turn, with slopes of up to 25% and with crops that are irregular in alignment and width of vegetation. Traction is provided by 4 hydraulic motors (again, one per wheel), operated with variable oil flow rate to limit localized slippage.
The harvesting unit
Again, action is taken on the plants by shaking the crowns: the olives detached from the plant are intercepted and then conveyed into special hoppers. The shaking apparatus consists of braked rods of various conformations oscillating in the transverse axis. More specifically, braked rods (a solution adopted by New Holland) are preloaded, that is, each is rigidly hinged at one end, while the opposite end is connected to an eccentric that causes the rhythmic variation of the curvature, causing--according to the manufacturer's claim--a gentle release of the olives. Instead, the curved rods are usually P-shaped and hinged at both ends.
The olives are then intercepted and conveyed using horizontal plastic bulkheads or baskets arranged in two continuously moving belts to the machine's rear, where a conveyor unit places the olives in hoppers. Each is equipped at the top with an auger that ensures uniform product distribution in the available volume. As an alternative to temporary storage on board, a "gooseneck" arm can be used to transfer the material to a tractor-drawn trailer parallel to the harvesting machine. Finally, the hoppers are emptied into trailers for transfer to the mill.