Harrowing #3
by J McCombie
Title
Harrowing #3
Artist
J McCombie
Medium
Photograph - Hdr
Description
The farmer harrows the hay field to prepare the land to plant a crop of corn.
A disc or disk 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 (the choices of the latter being determined by the final result required in a given soil type) and which are arranged into two sections ("offset disc harrow") or four sections ("tandem disc harrow"). 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.
In various regions of the United States, farmers call these implements just discs (or disks), and they reserve the word harrow for the lighter types of harrow, such as chain and tooth harrows. Therefore, in these regions, the phrase "plowing, disking, and harrowing" refers to three separate tillage steps. This is not any official distinction but is how farmers tend to speak. It is also common, at least in the United States, to consider disc plows to be a separate class of implement from discs (disc harrows). The first is a true plow, which does primary tillage and leaves behind a rough surface, whereas the second is a secondary tillage tool.
As nouns the difference between harrow and cultivator is that harrow is a device consisting of a heavy framework having several disks or teeth in a row, which is dragged across ploughed land to smooth or break up the soil, to remove weeds or cover seeds; a harrow plow while cultivator is any of several devices used to loosen or stir the soil, either to remove weeds or to provide aeration and drainage.
A harrow disturbs ALL the of the soil on the surface. It to smooths out the surface of the soil in the field. A harrow is often used after a plough to help reduce clumping of the soil. Harrows help prepare the soil before planting.
A cultivator is used to stir and move SOME the soil around before planting or after the crop has started to grow. The cultivator moves soil in a particular way to elicit a desired result. You can use a cultivator in a narrow path like between rows of plants. Sometimes that result can to help get rid of weeds by covering them up with soil. Cultivators usually don’t go very deep into the ground, so they work near the surface.
Tillage is the agricultural preparation of soil by mechanical agitation of various types, such as digging, stirring, and overturning and is often classified into two types, primary and secondary. There is no strict boundary between them so much as a loose distinction between tillage that is deeper and more thorough (primary) and tillage that is shallower and sometimes more selective of location (secondary). Primary tillage such as ploughing tends to produce a rough surface finish, whereas secondary tillage tends to produce a smoother surface finish, such as that required to make a good seedbed for many crops. Harrowing and rototilling often combine primary and secondary tillage into one operation.
"Tillage" can also mean the land that is tilled. The word "cultivation" has several senses that overlap substantially with those of "tillage". In a general context, both can refer to agriculture. Within agriculture, both can refer to any of the kinds of soil agitation described above. Additionally, "cultivation" or "cultivating" may refer to an even narrower sense of shallow, selective secondary tillage of row crop fields that kills weeds while sparing the crop plants.
A cultivator is any of several types of farm implement used for secondary tillage. One sense of the name refers to frames with teeth (also called shanks) that pierce the soil as they are dragged through it linearly. Another sense refers to machines that use rotary motion of disks or teeth to accomplish a similar result. The rotary tiller is a principal example.
Cultivators stir and pulverize the soil, either before planting (to aerate the soil and prepare a smooth, loose seedbed) or after the crop has begun growing (to kill weeds—controlled disturbance of the topsoil close to the crop plants kills the surrounding weeds by uprooting them, burying their leaves to disrupt their photosynthesis, or a combination of both). Unlike a harrow, which disturbs the entire surface of the soil, cultivators are designed to disturb the soil in careful patterns, sparing the crop plants but disrupting the weeds.
Cultivators of the toothed type are often similar in form to chisel plows, but their goals are different. Cultivator teeth work near the surface, usually for weed control, whereas chisel plow shanks work deep beneath the surface, breaking up hardpan. Consequently, cultivating also takes much less power per shank than does chisel plowing.
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May 31st, 2021
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