Fertilizer spreader
A fertilizer spreader is a spreader for the dosed and even application of granular fertilizers on agricultural areas such as fields or meadows . Fertilizer spreaders are built as attachments, trailers or self-propelled.
The drive is usually carried via a power take-off (PTO) of the tensile carrier vehicle, but there is also a fertilizer spreader propelled by electric motors , hydraulic motors or floor drive via the wheels of the device.
Application techniques
Different methods are used to distribute the fertilizers.
Centrifugal spreader
The centrifugal spreaders are further divided into pendulum tube and disc spreaders depending on the design of the distribution elements.
The most widespread is the disc spreader , also known as centrifugal spreader, in which the fertilizer is distributed by means of a disc-shaped centrifugal mechanism, similar to that of a road salt spreader to prevent ice formation on roads. The centrifugal mechanism consists of discs rotating horizontally or only slightly inclined at 700 to 1000 rpm, on which throwing bars are placed approximately radially. The fertilizer falling roughly in the middle of the rotating disc is caught by the throwing bars, accelerated and thrown away by the centrifugal forces that arise . The throw pattern of a disc spreader resembles a circular ring sector, provided it is not moved, the throwing distance depends on the speed of rotation of the disc and the size of the fertilizer grains. Single disc centrifugal fertilizer spreaders and twin disc centrifugal fertilizer spreaders are produced. Two-disc spreaders dispose of a more precise fertilizer distribution, since any asymmetries in the spreading pattern and the throwing angle of the spreading discs are balanced out by their opposite direction of rotation. With double disc spreaders, working widths of 10 to 50 m can be achieved.
With the pendulum tube spreader, however, the fertilizer is distributed by a tube that swings back and forth, the pendulum tube. The pendulum tube spreader is becoming less and less important in agricultural practice, despite evenly symmetrical distribution, as the working widths are limited to a maximum of 12 to 15 m.
With both types of centrifugal spreader, the amount of fertilizer spread is regulated by the size of the inflow from the fertilizer hopper to the spreading device. So that there is a constant supply of fertilizer and no lumps can form in the container, this is usually equipped with a stirring device. With the centrifugal spreaders, the amount of fertilizer distributed decreases towards the two edges of the spreading area. To ensure that the entire area is evenly sprinkled, the connections to the individual spreading widths are therefore made with a partial area covered. The overlapping scattering surfaces also have the advantage that the subsequent journeys do not have to be particularly precise.
Pneumatic or precision spreader
Another type of fertilizer distribution is the pneumatic spreader, also known as an exact spreader. Here, the fertilizer is dosed into an air stream and blown by the air stream via a pipeline onto various baffle plates mounted on a linkage across the working width. When it hits the plates, the fertilizer is spread widely. Boom widths of up to 36 m are currently available. The precision spreaders enable a very even distribution over the working width, but require precise follow-up driving and are very sensitive to wind in terms of application quality, especially with dusty or small-grain fertilizers.
Auger spreader
With the auger spreaders, the spreading material is conveyed by a worm that extends over the working width; the spreading takes place via adjustable openings in the worm casing. However, since the delivery rate of the auger decreases towards the edge of the working width depending on the spreading material, every change of the type of fertilizer to be distributed requires complex adjustment work on the spreading openings in the auger casing. However, the relatively low level of dust generation when spreading dust-like fertilizers such as fertilizer lime or Thomas flour is advantageous, especially if drag hoses are installed under the spreading openings.
Box fertilizer spreader
Box fertilizer spreaders distribute the fertilizer with a perforated rail that extends over the entire spreading width and various upstream vibrating or agitating units for tracking the spreading material.
They have become meaningless in agricultural practice.
Distribution and dosage requirements
The devices are designed in such a way that a plant-building needs-based supply of nutrients can be achieved through appropriate setting options. A distinction is made here between the distribution in the longitudinal direction (direction of travel) or transverse direction and the quantity metering. For optimal distribution, the spreading unit is set to the desired working width (between 10 and 50 m) depending on the flight characteristics of the fertilizer grain. In addition, the optimal dosage must also be tailored to the flow properties of the fertilizer.
Manufacturer
Among others, the following companies develop and produce fertilizer spreaders for both agriculture and winter service; Amazone , Bogballe, Kverneland , Bredal, Rauch and Unia.
literature
- Horst Eichhorn (editor): Landtechnik , 7th edition, Ulmer, Stuttgart 1952, 1999, ISBN 3-8001-1086-5 .
- Paul Schweigmann: The agricultural machines and their maintenance , 1st edition, Pfanneberg, Gießen 1955, reprinted by Bulldog-Press, Limburg ad Lahn 1993, ISBN 3-9803332-1-3 .
