page_title: Disc harrow
section_title: Offset disc harrow
hierarchical_section_title: Disc harrow / Offset disc harrow
caption_attribution_description: English: Asymmetric disk harrows (photo: Mihailo Grbić)
context_page_description: A disc harrow is a harrow whose cutting edges are a row of concave metal discs, which may be scalloped, set at an oblique angle. It is an agricultural implement that is used to till the soil where crops are to be planted. It is also used to chop up unwanted weeds or crop remainders.
  It consists of many carbon steel discs, and sometimes longer-lasting boron discs, which have many varying concavities and disc blade sizes and spacing and which are arranged into two sections or four sections. When viewed from above, the four sections would appear to form an "X" which has been flattened to be wider than it is tall. The discs are also offset so that they are not parallel with the overall direction of the implement. This arrangement ensures that the discs will repeatedly slice any ground to which they are applied, in order to optimize the result. The concavity of the discs as well as their offset angle causes them to loosen and lift the soil that they cut.
  A discer is an evolved form of a disc harrow, more suitable to Saskatchewan prairies, where it was developed in the 1940s. It does not leave ridging and it is lighter to pull, so it can be made bigger.
context_section_description: The heavy duty disc with large diameter disc blades of 26", 28", 30", 32", 36", and 40", and with increased disc spacings of 10", 14", and 18" are the primary tillage tools that are used to break virgin ground, to incorporate residue into the soil in preparation for a ripper / subsoiler, and to break up a compacted soil in order to increase soil aeration and to promote soil permeability in lower levels of the soil profile. Prior to a planting operation, a secondary disc harrow with narrow disc spacing of 8", 9", and even 10" with disc sizes ranging from 20", 22", 24", to 26" can be used. Other similar secondary tillage tine implements or rotary harrows are also widely used. When choosing secondary tillage equipment, soil type as well as soil moisture content at the time must be considered. Lighter secondary disc harrows are primarily used to break down soil clods into smaller pieces.  By so doing, water penetrates more easily into the soil, soil aeration is increased, and the activity of soil biota is enhanced; the final result is a seed bed that is suitable for planting.
caption: An offset (asymmetric) disc harrow
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