Tree transplanters

The models available on the market today can significantly increase transplanting productivity and quality. Transplanters are technologies used for interventions on all types of plants. They can be supported with ISOBUS systems and also complemented with localized irrigation technologies

Italy, the vine nursery sector is lively, particularly for fruit plants and tall trees for ornamental gardens or biomass production. For optimal development, it is crucial to plant young plants with care and attention to ensure that root establishment is ready and effective. Open field transplanting has traditionally been a rather onerous operation, primarily because of the long working time, which results in significant management costs and labor commitment. Hence, transplanting mechanization has recently undergone rapid development, resulting in the development of high-tech machinery that can significantly improve operating conditions and shorten lead times. 

Transplanters

The machine for the transplant is an implement carried on the 3-point hitch of the tractor's rear linkage, capable of performing a specific routine of operations intended to plant young tree plants. More specifically, it involves opening a furrow in the soil, subsequently inserting the plant, and closing the track with proper compression of the dislodged material around the stem. This prevents the plant from bending, a condition that would lead to failure of the work routine. A plowshare adjustable in width is generally adopted to make the furrow, followed by a series of belts or chains and tongs that guide the plant to the point of deposition, where it is released to be straightened and tamped. Depending on the type of transplanter and the accessories it is equipped with, one or more of the operations described requires the presence of one or more operators.

Most broadly, the transplanter should be characterized by versatility to adapt to different operating conditions, both in terms of plant size and transplanting distances on the row and between rows. Transplanters must be capable of planting both tall, biomass plants (e.g., poplar stems up to 2 m in height and 1-4 cm in diameter) and smaller specimens such as vine-rooted cuttings, fruit trees, hazelnuts, olive trees, lavender, Jatropha, and floral cuttings in general, all of which are significantly smaller material. 

Operating transplanters generally require tractors of up to 100 Hp and the work of 1-2 operators; for models with greater operating capacity, 100-120 Hp tractors are adopted, with the assistance of 3-4 workers. As a matter of fact, the size of the tractor is not so much conditioned by the power requirement of the equipment as by its tonnage, which is necessary to ensure appropriate stability at the site.

The transplanters' width depends on the number of stations set up for the operators but is generally contained within 3 meters, while their height is reduced to facilitate plant placement along the handling belt/belt.

Typical mass is about 7-800 kg, with significant variations depending on performance, as well as on additional equipment.

Standard transplanters can work on sloping terrain, generally up to 15 percent slope, but compensation systems are suitable for working on steeper slopes. For example, Arvatec's Basic-Drive Balance, which is well suited to hilly terrain, consists of an armored pc with a dual-frequency, multi-constellation GNSS receiver and UHF radio at 400-470 MHz, an inclinometer with 0.1° accuracy and a control unit.

A hydraulic motor with a motion sensor can be mounted as an option.

Compared with purely manual execution, the productivity of transplanters is, as is logical, enormously higher: on average, 20,000 up to as many as 40,000 plants/day can be planted.

Transplanter components and their operation

When working, transplanters use wheels to support them on the ground: Therefore, they are actually semi-supported models, resulting, nevertheless, being connected to the tractor via the attachment triangle.

The structure relies on a large support surface, which must allow easy placement by the operator(s) on the conveying organs of the young plants to be planted. Additionally, an adequate protective structure to prevent the operators' accidental falling on board must also be provided. Hence, the supporting surface can be simple, consisting of a platform for the proper stationing of the workers, or articulated into one or more seats for the seated position; in the latter case, hoppers, made up of basic inserts of the structure for the material to be placed are often installed. In this way, the workers' operations are optimized.

The tractor's PTO is primarily responsible for driving the working parts. It operates an independent hydraulic system consisting of a pump with its oil tank and radiator for its cooling, a series of distributors and actuators, consisting of belts or chains, completed with specific grippers. Thanks to special flow regulating valves, this technical solution has the advantage of freely adjusting the movement speed of the belts and tongs that bring the plants to the planting site with respect to the speed at which the yard advances, so the distance of the plants on the row can be varied within a wide range. 

The first stage of tillage is the opening of a furrow in the soil through an adjustable scythe or plowshare in width, which can vary between 8 and 20 cm, while vice versa, the depth varies between 15 and 45 cm.  After the young plant is placed in the furrow, special baffles recultivate the furrow with previously loosened soil, while at the same time, the operator or the support given by the rear support wheels keeps the plant upright. Finally, specific rear cultivators restore the soil around the plant. Where provided, a toothed wheel equipped with counting sensor stores the number of plants planted. 

For defining the transplanting density, the distance on the row between plants is a constant entered through the control panel of the control unit, considering that the row spacing varies between 40 and 60 cm in most cases.

ISOBUS control unit

If the coupled tractor is equipped with a GPS-assisted guidance system and an ISOBUS control unit, the transplanter can also perform more precise tillage with less worker effort. For example, Arvatec's application on the Wagner Universal X model, thanks to dedicated software, can automatically place the young plants in the exact locations intended. After storing the distance on the row and between rows, thanks to GPS, the planting error is minimal, usually within 5 cm. 

On the control unit's display, the operation's progress can be monitored in real-time so that any problems can be detected and solved immediately. Among other things, the solution described is fully compatible with the procedures of Agriculture 4.0 and therefore allows access to subsidies on purchasing advanced performance machinery.

Although even in this case, the presence of onboard workers is still required, their operation is considerably eased thanks to the presence of a grapple and integrated supports for positioning the young plants, which for an optimal level of comfort, are placed at eye level.

A few optional extras

For greater operational efficiency, localized drip irrigation hoses can be installed concurrently with transplanting by adding particular hose layers to the rear of the machine. A track-breaker is also sometimes available for heavy soils, with a considerable amount of clay, averting excessive soil compaction in the immediate surroundings of the young plant's laying site.