Precise and efficient, new technologies for transplanting

Thanks to ingenious construction solutions, modern transplanters for vegetable crops are capable of efficient planting of seedlings with or without clod, as well as bulbs, cuttings and seeds. Automation is progressively driving down the need for manpower

To maximize crop yields and aim for greater efficiency in the growing season in full field cultivations or protected plots modern horticulture is relying in large part on the technique of mechanical transplanting starting with seedlings with bare roots, soil blocks or often seedlings developed individually in plastic containers with a peat mix in various shapes and sizes, cubic, pyramidal, cylindrical. The mechanization of transplanting has now reached levels close to complete automation limiting manpower for feed in rootstock from trays to manage the single seedlings. The machine can open the furrow, plant out the seedling and close it, lightly compacting the soil around the seedling’s root apparatus to ensure sound mechanical stability all around the tiny plant in the right vertical position.

Planting in the ground, which can be performed in double rows, can be combined with the distribution of fertilizer, geodisinfestants, antifungus products and insecticides to protect the crop in the sensitive phase of early development. Moreover, the transplanter can also add a timely dose of water to boost bonding with the soil. The productivity of transplanters varies widely, depending on the number of rows worked with each pass and the degree of the automation of the machine which influences forward speed. In general, production ranges from about 2,000 to 8,000 seedlings/hour. 

Mounted, trailed and self-propelled

For productivity, there are models mounted on a tractor, or less commonly towed, and self-propelled transplanters. Though heavier and with greater bulk, the latter type is more manageable because it is a single unit and makes it possible to achieve a better use of labor. Once in the field, the operator of the self-propelled transplanter can pay attention to feeding in trays rather than tend exclusively to driving as is the case with tractor mounted machines or models towed off a three-point hitch.  

There are, in fact, self-propelled models equipped with devices for maintaining the ideal advance of the machine with the use of a sensor in contact with the bottom of the furrow created with the previous nearby pass by a pair of wheels for ideally controlling steering to correctly maintain the traversal distance of the transplanter, even when plants are planted in double rows.

The drive of these self-propelled machines is often hydraulic rather than mechanical to benefit from gradual progression in moving and making it possible to finely regulate the most suitable speed of advance. In any case, engines are usually internal combustion with relatively low power, at a maximum of 35-40 HP, because they are needed only for driving the machine forward and possibly powering accessories. This is also the case for mounted and trailed models in that the distribution and transplanting components are run off the machine’s wheels or a specific wheel dedicated to powering them.

In this way efficient transplanting is achieved in relation to the advance of the machine for maintaining uniform distances between the deposit of seedlings in the row aside from the inevitable variations of speed. In this connection, the wheel cited is a steel rim equipped with pneumatics and ridged for a better grip of the soft seedbed.

The single transplanter components are usually mounted on a mainframe with quadrilateral articulation to provide the machine free vertical play needed for absorbing the inevitable highs and lows of the terrain.

 

Onboard storage of materials for transplanting

Unlike what may be imagined, feeding seedlings to the transplanter distributor can take on great importance because of the risk of this factor limiting the capacity of the machine, especially those which are highly automated. In general, storage aboard must facilitate and guarantee speedy replacement of the empty trays by the operator on board as well as a quick exchange for filling the empty distributor cups on the transplant unit. Generally available for this are canted tray holders which overlap or are located on a rotating cylinder. The first of these two arrangements is advised for feeding semi-automatic machines because with this solution an entire row of earthed seedings, always pyramidal shaped, can be quickly accessed and put in place on the dedicated feeder and device and the plastic containers separated ahead of planting.

 

Transport devices

The configuration of the vegetable materials to transport and the mechanisms for lifting and transporting seedlings to the soil vary substantially. One of the common solutions for handling bare roots, earthed seedlings and woody cuttings is a belt, equipped with pincers, which rotates vertically. A pincer opens when it reaches the top of the rotation allowing manual placement of a single seedling. During the rotation, the pincer exerts gentle pressure to keep the seedling in position and then plants it correctly in the furrow created in the meantime. 

An interesting variation on this system was achieved by Hortech in Agna, near Padua, with the Over model transplanting machine which can operate on raw soil prepared with mulch in polyethylene and paper or Mater-Bi to plant clod seedlings in pyramidal and square shapes as well as bulbs and seeds. In practice, real furrows are not created as the machine is equipped with a belt which rotates vertically on which are mounted beaked cups for carrying the materials. The beaks close to hold the seedling, penetrate the soil forming a hole in the mulch, if present, and open to create the hole in which the vegetable material is planted.

An alternative to this method is provided with other models equipped with cylinders, sometimes elongated, which rotate on a horizontal axis with specific lengthening for bedding seedlings.

Afterward a vertical conveyer intercepts the seedlings and locates them in the furrow created in the meantime. An alternative is the Rotostrapp from Ferrari Costruzione Meccaniche in Guidizzolo, near Mantua, a transplanter available in trailed and self-propelled versions built in modular units for bedding compressed square soil blocks in quincuncial or “diamond” layouts with very high productivity of up to 8,000 plants/hour with a belt which directly conveys the seedlings to the soil. The use of manpower in typical mechanical transplanting operations is always significant, especially for ensuring the continuous and regular feeding of the seedlings to the machine’s distributor component. For this reason, Ferrari Costruzione Meccaniche markets an interesting solution for carrying out work with a single operator. With the Futura Twin automatic model, the only manual operation required is the placement of trays in the guide for loading the single plants.

The Futura Twin is equipped with a shuttle device to feed trays to the transplanter robot. Every robot extracts the seedlings automatically by means of a system based on cylindrical plungers combined with moving fingers that will pick up the plugs coming out from the tray thanks to the bottom pressure of the plungers. The seedlings are then picked up by mobile pincers and placed on the distributor. The productivity rate is very high, up to 8,000 plants/hour and in this case the machine is equipped with a failure screen with a memory for discrimination, replacement and mechanical recovery of the empty cups.

Burying, furrow closing and soil compacting devices

If a furrow is required a small furrow opening share is used, a component sometimes equipped with automatic cleaning of the soil which adheres to it. Otherwise, the solution applied is the creation of a small hole in the soil in which to place the seedling.

The furrow must be closed and then approached for compacting the surrounding soil moved to give the plant the stability needed and especially ensure bonding with the soil to make it ready for optimum development of the root apparatus. Used for this purpose are coulter blades or more often a pair of free-wheeling ridged and converging wheels, possibly ringed in rubber, which are especially useful for working on sticky terrain. 

BOX: Mulching for transplanting

Mulch is a layer of vegetable materials, leaves, twigs and the like, which accumulates naturally under trees and breaks down progressively over time.

Mulch can be made up of organic products such as leaves, pruning residues, lawn mowing cuttings, sawdust, wood chips, cortex, compost, cereal straw and the like, or inorganic materials, stone granules, gravel, volcanic ash, etc. produced especially for this purpose, as well as sheets of plastic materials. This latter product is especially beneficial with advantages for: more or less totally eliminating infestation species for a sharp reduction in the use of weedkillers and selective mechanical weeding; reducing the irrigation of the crop because mulch effectively counters the evaporation of water from the soil surface and enhances the capillary rise of moisture from the lower layers without competition from weeds; hastening harvesting and increasing yields because the soil is heated more quickly and holds in accumulated heat; improving the use of nutritional elements thanks to greater intensity of microorganism activities in the soil due to higher average temperatures; lowering washing away of fertilizers, especially nitrate, on the surface and at lower levels thanks to reducing the risk of erosion caused by rain and irrigation and also reducing surface soil compaction; the production of fruit and vegetables without ground pollution due to the absence of physical contact with the soil.

On the other hand, the only two problems to evaluate are the cost of mulch film and especially dismantling it in the case of use of traditional plastic materials, polyethylene, PE, especially if the film is smeared with plant treatment products and/or earth.

New biodegradable materials in Mater-Bi based on cornstarch have been available for some time. These decompose in 3-14 months, basically in relation to the temperatures, humidity and microbiological activities in the terrain as well as, obviously, the thickness of the film. The film comes in colors which are generally black, green, brown or white and is designed for no interference in biodegradation. It features the same resistance, elasticity and efficiency as film in PE.

The characteristics of the film allow it to be spread with standard transplanters with the single caution to relax the tension while laying it out. The holes necessary for planting out seedlings need no special attention.

The costs of this biodegradable film are comparable with traditional film when taking into account that there are no costs associated with dismantling them. 

BOX: Also rubber track

Checchi & Magli in Budrio, near Bologna, markets the Rio 31, a self-propelled transplanter which can be configured for planting 1 to 8 rows powered by a 31 Hp Yanmar diesel engine and equipped with hydrostatic drive. Thanks to its versatility, the machine can be considered a multi-purpose utility.

The special feature of this model is that instead of wheels, the Rio 31 mounts rubber tracks 250 mm wide. Among their advantages is lower compaction of the soft seedbeds due to their wide impact on the terrain compared to standard rubber tires.

Moreover, this unit is remarkably stable because of a very low center of gravity and the track ensures greater grip for the efficient longitudinal and traversal travel of the transplanter even on terrain with slopes of up to 60%, with no lateral slippage or swerving.