Harrow (agricultural engineering)
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A harrow is an agricultural tillage implement that has tines that move through the ground. It is used to loosen the upper soil layer, to break up clods of earth, to create good crumbs for the preparation of the seedbed and to control weeds. After the broad sowing , the harrow is used to incorporate the seeds . Harrows can dig into the ground more or less sharply. Very light harrows are also called harrows , deeper harrows can also be called cultivators .
meaning
Originally, the harrow consisted of a tine structure, initially made of wood , later exclusively of steel .
The word syllable egg has the same origin as the Latin acer for 'sharp, cutting'.
Harrows create a relatively fine soil condition due to the large number of tines. Along with the plow, they are the farmer's main work tool. Some heavy types can also be used for stubble falling or for tillage without a plow.
The harrow can also be used to control weeds or level uneven fields. By loosening and crumbling the top soil layer, the soil capillaries are broken and the evaporation of soil moisture is reduced. It is pulled by draft animals or tractors .
Harrows by type
There is a large selection of harrow types for the various areas of application. In addition to traditional zinc harrows, harrows with and without drive are also used.
Harrows without drive , i.e. pulled harrows or harrows driven over the ground, are divided into zinc harrows and disc harrows. The disc harrow, also known as a disc harrow, is a special form. The disc harrow also includes the spade harrow.
With the PTO driven will include the harrow or rotary cultivator and harrow . All modern powered harrows usually have a directly mounted roller as a support, depth control and to reconsolidate the soil.
Zinc harrow
The tine harrows are divided into harrows with rigid tines and the spring tine harrow / spring tine harrow (also called cultivators or seedbed combinations). Special forms are the spoon harrow, net harrow, swash harrow and meadow harrow.
Net harrow
The net harrow (also called harrow ) consists of a net-like wire mesh in which the tines, also made of wire, are attached. This type of harrow is particularly manoeuvrable and therefore adapts to any uneven ground. It is used for weed control; their tines tear or shed due to their circular, touching movements, little weed seedlings and young plants, whereas the already more developed crops are not permanently damaged. Due to the light construction and the low working depth, a harrow is far easier to pull than other types of harrows. Despite its usually larger working width, it therefore only requires light maintenance tractors as tractors and still achieves large area outputs per hour. Due to its low working depth, it can also be used shortly before the crop emerges.
Meadow harrow or grassland harrow / grassland harrow
The meadow harrow is a special harrow for use on meadows . It is used there to remove moss , level molehills or evenly distribute manure , cow dung or slurry crusts . In addition, their use injures the sward and thus stimulates it to grow.
The meadow harrow can also be used for leveling harness racing tracks , riding arenas or simply leveling soil. The meadow harrow consists of a frame in which steel plates with short prongs hang on the underside.
The modern type of grassland maintenance is carried out with a grassland harrow (with and without an undersowing device). Leveling rails level the molehills and cow dung, the harrow tines distribute the organic material. In addition, they ventilate the sward, tear open matting and create gaps by combing out weeds, which are closed by reseeding with valuable seeds. Grassland maintenance not only increases yield and nutritional value, it also reduces weed pressure by preventing the creation of gaps where weeds can grow. As an option, the grassland harrow can be equipped with pressure rollers.
Rotary harrow
The harrow or rotary harrow is an agricultural implement for working the soil, especially for seedbed preparation before sowing. The rotary harrow is usually connected with a three-point linkage to a tractor , which drives the device with the aid of a cardan shaft . The cardan shaft leads to an angular gear, which in turn drives a large number of rotors depending on the working width, which are evenly distributed in a row on the tool carrier at intervals of 25 cm or 30 cm. Each rotor is equipped with a pair of tines attached to a tine holder via a vertical shaft. The tines, also known as rotary knives, have a length of around 25 cm and work in different soil depths depending on the type of fruit to be sown. The working speed is 6 to 10 km / h with a speed of the rotors of around 350 to 420 / min.
The rotary harrow is available in working widths from 2.0 m to 4.5 m in a rigid design, whereas the larger working widths (up to 8 m) can be folded up hydraulically for transport. A seed drill can also be built onto the rotary harrow in order to reduce the separate sowing process to a single operation, which means cost savings and soil protection .
Rotary cultivator
The rotary cultivator is a variant of the rotary harrow that differs from it in that the tines are not dragged, but are mounted "on the handle". The rotors are arranged at a distance of around 30 cm, whereas the majority of rotary harrows have a rotor distance of 25 cm and thus work more intensively on plowed soil. Rotary cultivators with “tines on the handle” are mainly used for mulch sowing (without a plow) in order to mix stubble and possibly also straw with the soil. The tine tips of the power harrow point straight down. The tines of a rotary cultivator are slightly curved. The seed coulters of the seed drill place the seed directly in the mulched soil. When the seed drill is connected to the rotary harrow / cultivator, soil cultivation and sowing are carried out in one operation.
Tine rotor (harrow)
In a tine rotary harrow, the tines are attached to a rotor, similar to a tiller . The tine rotary harrow can be used to work both stubble fields and fields that have already been worked. Since no previous soil cultivation is necessary, the tine rotary harrow can be used for soil-conserving cultivation. However, a sufficiently motorized tractor is necessary (at least 50 HP per meter of working width).
Power harrow
The power harrow consists of only two parallel tine bars mounted at right angles to the working direction with rigid, vertical harrow tines, similar to the rigid tine harrow, as in the picture above. An oscillating drive (wobble drive = wobble harrow) causes the two harrow bars to move in opposite directions, oscillating to the side of about 10 cm, which gives this device a crumbling effect similar to that of a rotary harrow. Vibrating harrows are much lighter than rotary harrows and are more suitable for lighter soils or for smaller clods of earth. Large, sticky clods are broken only slowly and cause soil to accumulate in front of the tine bar and thus bumps. Larger working depths often lead to undesirable earth walls that are thrown up at the side and can therefore often not be used.
Disc harrow or plate harrow
The disc harrow ( also known as a disc harrow ) consists of curved discs that rotate at an angle and cut open and mix the soil in a similar way to a plow. Usually two counter-rotating disc beams - often provided with serrated discs in the front row and smooth discs in the back row - work together to cut the entire soil horizon. It has the advantage of germinating so-called lost grain ( grains that fell out of the combine harvester during harvest ) and thus accelerating emergence.
Classic disc harrows have all discs in a row on an inclined axis and therefore have a greater overall length than compact disc harrows, the discs of which are individually mounted diagonally and therefore manage with shorter overall lengths. Compact disc harrows can therefore be carried on the three-point hydraulic system rather than classic disc harrows, which are generally equipped with their own chassis. The working speed is about 10 km / h. The working speed of compact disc harrows is higher, usually around 12-15 km / h.
Spade harrow
The spade harrow (also called wing harrow ) developed in Finland is a much lighter variant of the disc harrow. Instead of the discs, it only has individual “spades”, quasi disc segments, which are particularly suitable for tillage in stubble. The working speed is around 12 km / h.
See also
Individual evidence
- ^ Schlipf, Handbuch der Landwirtschaft, 13th and 32nd edition, Verlag Paul Parey, Berlin (and Hamburg), 1898 and 1958, § 28 and p. 52 ff., Both reprinted by Manuscriptum Verlagsbuchhandlung, Waltrop and Leipzig, ISBN 978-3-933497-77-2 .
- ^ Michael Koch, Traditional work with horses, Ulmer, Stuttgart 1998, ISBN 3-8001-7383-2 , page 53 f.
Web links
- Use of the harrow (museum site)
- Harrow . In: Meyers Konversations-Lexikon . 4th edition. Volume 5, Verlag des Bibliographisches Institut, Leipzig / Vienna 1885–1892, pp. 329–330.
- systematically and in detail Lueger, Otto: Lexicon of the entire technology and its auxiliary sciences, Vol. 3 Stuttgart, Leipzig 1906., pp. 221–222, [1]