Disking is a farm management practice used for soil preparation. It usually follows plowing, either deep or shallow. While plowing cuts, granulates, and inverts the soil, creating furrows and ridges, disking breaks up clods and surface crusts. Additionally, disking improves soil granulation and surface uniformity. As one of the most important soil preparation practices, disking is beneficial for provoking the weed growth and destroys already emerged weeds. It also assists in the important task of incorporating crop residues into the soil.
Disc Harrows: Implements for Soil Preparation Management
Disc harrows are farming implements used to prepare the soil for planting or sowing by breaking up the clods and surface crusts, thus improving soil granulation and destroying the weeds. They consist of concave cutting blades (disks), mounted on a common shaft, that form a gang. The disc harrow consists of the following parts:
1. Frame; holds and supports the disc harrow
2. Disc; circular concave cutting blade made of steel. There are the two types of discs:
- Smooth edge disc; also called plain edge disc; consists of plain discs used for normal soil conditions
- Notched edge disc, also called cut-away discs or scalloped edge discs with serrated edges; used for cutting crop residues and weeds
3. Arbor bolt; also called gang bolt, is a long heavy steel shaft on which discs are mounted
4. Spool or spacer; component mounted on arbor bolet between every two discs to retain their fixed position and prevent any lateral movement of the disc
5. Bearings; essential for providing rotation of the gang and regulating the thurst
6. Bumper; heavy iron plate situated at the end of each gang to counter; protects the discs from collision of adjacent discs
7. Scraper; removes the soil from the disks, keeping the concave side of the disk clean, thus preventing the clogging of the discs
8. Disc gang; each group of disks mounted on a common arbor bolt with disc spacer, bearing, and bumper; may consist of 3 to 13 discs
9. Weight box; included on the frame to provide additional weight for increasing the penetration of the disc into the soil
Types of Disc Harrows
There are various types of disc harrows. Regarding of the operation mode, there are three different types of disc harrows:
- Single action disc harrow; consists of two disc gangs arranged in opposite directions, it throws the soil in opposite directions creating ridges and furrows
- Double action disc harrow; also called tandem disc harrow; consists of two or more gangs, discs from the front gangs throw the soil in one direction, while discs on the rear gangs throw the soil in the opposite direction
- Offset disc harrow; consists of two gangs (left and right) operating in tandem; the harrow is usually placed in the offside of the tractor so it is not in the same line of pulling the tractor
Aside from the aforementioned classifications, disc harrows can be classified according to the type of mounting used with the tractor (mounted, semi-mounted, trailed), as well as by the size of the disc.
In regards to the disc diameter, there are three different disc harrows:
- Light disc harrows; with a disc diameter of 20-30 cm
- Middle disc harrows, with a disc diameter of 30-50 cm
- Heavy disc harrows, with a disc diameter more than 60cm
The type of harrow disk a farmer chooses for soil preparation management will depend on the purpose of disking, whether it’s intended for entering the crop residue or simply leveling the soil structure. Another important aspect to consider when choosing the most appropriate type of disc harrow is the size of the field.
Larger fields demand improved farm equipment, while smaller fields can be managed with the simple farm implements such as the single action disc harrow. So make sure you choose the most appropriate disc harrows for your soil preparation management.