In the process of harrowing the soil, loosening, mixing and leveling of its surface layer is carried out without turnover of the formation. It is carried out using agricultural machines - harrows. This is the short answer to the question "What is a harrow?".
Harrowing technology
This process provides moisture closure, to some extent contributes to the removal of weeds. Harrowing can be carried out before emergence and after their emergence. As a rule, it is carried out perpendicular to the direction of crops or on a diagonal. It is carried out at a time when the soil moisture is in the range of 50-70%, since neither dry nor waterlogged soil contribute to the proper deepening of the working organs, which leads to poor-quality processing. Harrowing is often combined with cultivation. And different harrows can be used: spring, disk, light, heavy, rotary, etc.
The tractor speed when performing this technique should be about 8 km / h, while harrowing winter crops in the spring - 6 km / h.
Tooth harrows
What is a harrow? This is an agricultural tool designed to perform the harrowing process. Today, two types of harrows are produced: tooth and disc harrows.
Consider the first of them.
Using them, the soil can be cultivated up to 10 cm. Furrows during cultivation with this type of harrow should be no more than 4 cm deep. Lumps should be destroyed to a maximum of 5 cm.
Dental harrows are divided into lungs (with pressure on the working organs of about 1 kg), medium (respectively 2 kg) and heavy (3 kg).
The most widely used heavy zigzag harrow. It is used to achieve harrowing goals for most crops.
The middle harrow is used on loose light soils. The depth of its processing is 5-6 cm.
Light harrows are used only for leveling the surface, slightly combing out newly emerged weeds and removing soil crust. The depth of treatment with this harrow is up to 3 cm.
The working bodies of the harrow are represented by teeth, with the help of the front part of which the upper part of the soil is cut, and with the help of the lateral soil particles are moved apart, crushed, and lumps are destroyed, and the soil elements are mixed.
Harrow frames can be rigid and articulated. The latter provide better copying of the soil topography, as a result of which the best uniformity of processing is ensured.
The teeth may be curved, straight and clawed. They are located in one row at a distance exceeding 15 cm, with the aim of eliminating the clogging of weeds and clods of earth.
One of the varieties of this type of harrow is a mesh harrow, which is flexible and provides uniform processing even in areas with irregularities.
Dental harrows are usually coupled with plows, cultivators, seeders, which, in turn, are aggregated with tractors.
The number in the name, as a rule, shows the width in meters.
Disc harrows
What type of harrow is this type of harrow? As a rule, these harrows have wheels, except for those brands that are designed to handle thick turf.
The working bodies are discs that easily crush soil lumps, loosen the soil and cut the sod. Each disc of the harrow is located at a certain angle with respect to the direction of movement, which is called the angle of attack.
Fog areas are treated with cut-out discs.
The frame with wheels is designed to control the depth of tillage. Compared to teeth, discs become clogged with soil and weeds less, cut thin roots better and roll through thick ones. However, they cannot be used on rocky areas.
By appointment, they are classified into marsh, garden and field.
For processing soddy soil, marshy soil, pastures and meadows, a heavy disk harrow is used, which can be adjusted to a depth of 20 cm.
The disks are not mounted individually, but together, making up batteries. The discs are separated from each other by means of a spacer bobbin. On the square axes there are bearings that provide rotation of the disk batteries, which are arranged in two rows on the frames, the front of which works in a camber, and the rear in a dump.
Angles of attack are set depending on the hardness and moisture of the soil. Higher angles of attack are established on hard and dry soils (up to 21 degrees). A higher angle of attack provides better immersion of disks in the soil, and, therefore, better processing.
In addition to changing the angle of attack, the depth of processing is regulated by changing the pressure of the disk batteries on the soil due to a change in the mass of ballast, as well as the compression force of the spring mechanism.
Spring type device
The spring harrow is used for harrowing after harvesting and for sowing. With its help, in addition, they perform functions traditional for harrows: loosening and leveling the surface of the soil. In addition, this type of harrow is used for inter-row tillage without damaging cultivated plants during this operation. It can also be used for filling fertilizers, collecting hay and straw in rolls. This device is a type of tooth harrow.
The working body of this harrow is a spring of a certain section. Under load, it plays in different directions, due to which, with a processing speed exceeding 12 km / h, more or less continuous overlap is provided.
Here, as with the disc harrow, the angle of attack is adjusted.
In the spring harrow "Agristar" there are copying sections that provide uniform processing independent of the relief.
Depth adjustment is carried out by changing the angle of attack, as well as by changing the tension of the springs on each section.
Spring teeth can have different diameters, which allows these devices to also be divided into light, medium and heavy.
Some brands provide the possibility of mounting a pneumatic sowing device, so that it can be used for sowing various crops of continuous sowing.
Rotary device type
These devices are mainly called not just harrows, but harrows-hoes. They are used mainly in areas of insufficient moisture, as well as in conditions when cultivated plants pass the phase of the possible use of dental harrows.
Rotary harrow consists of pairs of discs that are located on the horizontal axes. On the disk there are wedge-shaped teeth having beveled sections. The working width of these types of harrows ranges from 1.1 to 18.3 m.
With the help of rotary harrows it is possible to close up fertilizers, crop residues. Depth of processing can be up to 28 cm (for Polish models).
Trailed and mounted harrows
Harrows according to the method of aggregation are classified into trailed and mounted.
Trailed harrows have wheels that perform the function of a support. This type is convenient for transportation.
Mounted harrows rely on working bodies, they are usually small in size. They are kept in the air during transportation due to the connection with the tractor.
Needle harrow
What is a needle harrow? This is a harrow used for anti-erosion treatment in combination with other agricultural machines instead of other types of harrows. Its passage ensures that up to 90% of the stubble is left, which prevents erosion. This type includes BIG-3 harrows and its modification BIG-3A.
One harrow has a working width of 3 m, is aggregated with tractors MTZ, YuMZ. Three harrows are aggregated with T-150 tractors, five - with K-700 heavy tractors.
It can, in addition to the functions traditional for harrows, perform the destruction of the ice crust on winter crops.
The BIG-3 device includes 4 sections in 2 rows, there are wheels. Like the disc harrow, the angle of attack is adjustable.
Working bodies are disks with 12 needles. The first row consists of 8 discs located in 2 batteries. The back row includes 9 discs. The angle of attack is 8-16 degrees.
Discs with needles can be mounted in an active or passive state. With an active installation, the disks enter the soil layer with a bulge up, go out - down, with a passive - vice versa. These methods affect the contamination of the harrow. At the rear of the harrows are grilles for cleaning discs. With passive installation, these grilles are clogged to a lesser extent.
A wide-grip aggregate can be created from harrows, for which they are connected by restrictive chains in order to till the soil without blemishes.
We collect the harrow ourselves
It is quite problematic for summer residents to buy a tractor and a harrow for it. Some of them have motoblocks to which you can assemble the harrow with your own hands.
To do this, we take a pipe of metal, weld the same strip, with the help of screws we attach the teeth. At the end of the drawbar we place a finger of metal to connect the harrow to the walk-behind tractor. It is also necessary to provide a rack for regulating the height of the harrow, designed to evenly deepen the working bodies. It provides for an adjustment screw.
Finally
Thus, to the question "What is a harrow?" we can answer that this is an agricultural tool used in agriculture with the aim of closing moisture, combing weeds and combating soil crust. Different types of harrows are used depending on the type of soil, its particle size distribution, and the amount of moisture in the region.