In agriculture

Agriculture

Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

, a harrow (often called a set of harrows in a plurale tantum

Plurale tantum

A plurale tantum is a noun that appears only in the plural form and does not have a singular variant for referring to a single object...

 sense) is an implement for breaking up and smoothing out the surface of the soil

Soil

Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

. In this way it is distinct in its effect from the plough

Plough

The plough or plow is a tool used in farming for initial cultivation of soil in preparation for sowing seed or planting. It has been a basic instrument for most of recorded history, and represents one of the major advances in agriculture...

, which is used for deeper tillage

Tillage

Tillage is the agricultural preparation of the soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shovelling, picking, mattock work, hoeing, and raking...

. Harrowing is often carried out on fields to follow the rough finish left by ploughing operations. The purpose of this harrowing is generally to break up clods (lumps of soil) and to provide a finer finish, a good tilth

Tilth

Tilth can refer to two things:Tillage and a measure of the health of soil.Good tilth is a term referring to soil that has the proper structure and nutrients to grow healthy crops. Soil in good tilth is loamy, nutrient-rich soil that can also be said to be friable because optimal soil has a mixture...

 or soil structure

Soil structure

Soil structure is determined by how individual soil granules clump or bind together and aggregate, and therefore, the arrangement of soil pores between them...

 that is suitable for seedbed

Seedbed

A seedbed or seedling bed is the local soil environment in which seeds are planted. Often it comprises not only the soil but also a specially prepared cold frame, hotbed or raised bed used to grow the seedlings in a controlled environment into larger young plants before transplanting them into a...

 use. Such coarser harrowing may also be used to remove weed

Weed

A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...

s and to cover seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

 after sowing. Harrows differ from cultivator

Cultivator

A cultivator is any of several types of farm implement used for secondary tillage. One sense of the name refers to frames with teeth 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...

s in that they disturb the whole surface of the soil, such as to prepare a seedbed, instead of disturbing only narrow trails that skirt crop rows (to kill weeds).

There are four general types of harrows: disc harrow

Disc harrow

A disc harrow is a farm implement that is used to cultivate the soil where crops are to be planted. It is also used to chop up unwanted weeds or crop remainders. It consists of many iron or steel discs which have slight concavity and are arranged into two or four sections...

, tine harrow, chain harrow and chain disk harrows. Harrows were originally drawn by draft animals

Working animal

A working animal is an animal, usually domesticated, that is kept by humans and trained to perform tasks. They may be close members of the family, such as guide or service dogs, or they may be animals trained strictly to perform a job, such as logging elephants. They may also be used for milk, a...

, such as horses, mules, or oxen, or in some times and places by manual labour

Manual labour

Manual labour , manual or manual work is physical work done by people, most especially in contrast to that done by machines, and also to that done by working animals...

ers. In modern practice they are almost always tractor

Tractor

A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...

-mounted implements, either trailed after the tractor via a drawbar

Drawbar (haulage)

A drawbar is a solid coupling between a hauling vehicle and its hauled load. Drawbars are in common use with rail transport, road trailers, both large and small, industrial and recreational, and with agricultural equipment.-Agriculture:...

 or mounted on the three-point hitch

Three-point hitch

The three-point hitch most often refers to the way ploughs and other implements are attached to an agricultural tractor. The three points resemble either a triangle, or the letter A...

.

Types

In cooler climates the most common types are the disc harrow

Disc harrow

A disc harrow is a farm implement that is used to cultivate the soil where crops are to be planted. It is also used to chop up unwanted weeds or crop remainders. It consists of many iron or steel discs which have slight concavity and are arranged into two or four sections...

, the chain harrow, the tine harrow or spike harrow and the spring tine harrow

Spring-tooth harrow

A spring-tooth harrow, sometimes called a drag harrow, is a type of tine harrow, and is a largely outdated piece of farm equipment. It uses many flexible iron teeth mounted in rows to loosen the soil before planting...

. Chain harrows are often used for lighter work such as levelling the tilth or covering seed, while disc harrows are typically used for heavy work, such as following ploughing to break up the sod

Sod

Sod or turf is grass and the part of the soil beneath it held together by the roots, or a piece of thin material.The term sod may be used to mean turf grown and cut specifically for the establishment of lawns...

. In addition, there are various types of power harrow, in which the cultivators are power-driven from the tractor rather than depending on its forward motion.

Tine harrows are used to refine seed-bed condition before planting, to remove small weeds in growing crops and to loosen the inter-row soils to allow for water to soak into the subsoil. The fourth is a chain disk harrow. Disk attached to chains are pulled at an angle over the ground. These harrows move rapidly across the surface. The chain and disk rotate to stay clean while breaking up the top surface to about 1 inches (3 cm) deep. A smooth seedbed is prepared for planting with one pass.

Chain harrowing may be used on pasture land to spread out dung, and to break up dead material (thatch) in the sward, and similarly in sports-ground maintenance a light chain harrowing is often used to level off the ground after heavy use, to remove and smooth out boot marks and indentations. When used on tilled land in combination with the other two types, chain harrowing rolls the remaining larger clumps of soil to the surface where the weather will break them down and prevent interference with seed germination.
All four harrow types can be used in one pass to prepare the soil for seeding. It is also common to use any combination of two harrows for a variety of tilling

Tillage

Tillage is the agricultural preparation of the soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shovelling, picking, mattock work, hoeing, and raking...

 processes. Where harrowing provides a very fine tilth, or the soil is very light so that it might easily be wind-blown, a roller

Roller (agricultural tool)

The roller is an agricultural tool used for flattening land or breaking up large clumps of soil, especially after ploughing. Typically, rollers are pulled by tractors or, prior to mechanisation, a team of animals such as horses or oxen....

 is often added as the last of the set.

Harrows may be of several types and weights, depending on the intended purpose. They almost always consist of a rigid frame to which are attached discs, teeth, linked chains or other means of cultivation, but tine and chain harrows are often only supported by a rigid towing-bar at the front of the set.

In the southern hemisphere the so-called giant discs are a specialised kind of disc harrows that can stand in for a plough in very rough country where a mouldboard plough will not handle the tree-stumps and rocks, and a disc-plough is too slow (because of its limited number of discs). Giant scalloped-edged discs operate in a set, or frame, that is often weighted with concrete or steel blocks to improve penetration of the cutting edges. This sort of cultivation is normally immediately followed by broadcast fertilisation and seeding, rather than drilled or row seeding.

A drag

Drag harrow

A drag harrow, a type of spring-tooth harrow, is a largely outdated type of soil cultivation implement that is used to smooth the ground as well as loosen it after it has been plowed and packed. It uses many flexible iron teeth usually arranged into three rows. It has no hydraulic functionality...

 is a heavy harrow.

Historical reference

In Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, harrows were first used in the early Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

.

The following text is taken from the Household Cyclopedia

Household Cyclopedia

The Household Cyclopedia was an American guide to housekeeping published in 1881.- External links :**...

of 1881:

"When employed to reduce a strong obdurate soil, not more than two harrows should be yoked together, because they are apt to ride and tumble upon each other, and thus impede the work, and execute it imperfectly. On rough soils, harrows ought to be driven as fast as the horse

Horse

The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

s can walk; because their effect is in the direct proportion to the degree of velocity with which they are driven. In ordinary cases, and in every case where harrowing is meant for covering the seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

, three harrows are the best yoke, because they fill up the ground more effectually and leave fewer vacancies, than when a smaller number is employed. The harrowman's attention, at the seed process, should be constantly directed to prevent these implements from riding upon each other, and to keep them clear of every impediment from stones, lumps of earth, or clods, and quickens or grass roots; for any of these prevents the implement from working with perfection, and causes a mark or trail upon the surface, always unpleasing to the eye, and generally detrimental to the vegetation of the seed. Harrowing is usually given in different directions, first in length, then across, and finally in length as at first. Careful husbandmen study, in the finishing part of the process, to have the harrows drawn in a straight line, without suffering the horses to go in a zigzag manner, and are also attentive that the horses enter fairly upon the ridge, without making a curve at the outset. In some instances, an excess of harrowing has been found very prejudicial to the succeeding crop; but it is always necessary to give so much as to break the furrow, and level the surface, otherwise the operation is imperfectly performed."

George Orwell, as a soldier in 1937 in a Spanish Civil War

Spanish Civil War

The Spanish Civil WarAlso known as The Crusade among Nationalists, the Fourth Carlist War among Carlists, and The Rebellion or Uprising among Republicans. was a major conflict fought in Spain from 17 July 1936 to 1 April 1939...

 anti-fascist unit three miles east of Huesca

Huesca

Huesca is a city in north-eastern Spain, within the autonomous community of Aragon. It is also the capital of the Spanish province of the same name and the comarca of Hoya de Huesca....

, Aragon

Aragon

Aragon is a modern autonomous community in Spain, coextensive with the medieval Kingdom of Aragon. Located in northeastern Spain, the Aragonese autonomous community comprises three provinces : Huesca, Zaragoza, and Teruel. Its capital is Zaragoza...

, found inside “a derelict hut in no man’s land” a harrow of primitive design:

"There was a kind of harrow that took one straight back to the later Stone Age. It was made of boards joined together, to about the size of a kitchen table; in the boards hundreds of holes were morticed, and into each hole was jammed a piece of flint which had been chipped into shape exactly as men used to chip them ten thousand years ago."

See also

• List of agricultural machinery
• Roller (agricultural tool)
  Roller (agricultural tool)
  The roller is an agricultural tool used for flattening land or breaking up large clumps of soil, especially after ploughing. Typically, rollers are pulled by tractors or, prior to mechanisation, a team of animals such as horses or oxen....
  
  
• Harrower (surname)

External links

• "Degelman Strawmaster Harrows" Tine Harrows
• "Little Harrows" Song parody
• "Martens Harrows" Spike harrows
• "Pepin Harrows" Spike & Coil Tine Harrows
• "May-Bridge Harrows" Chain harrows
• Examples of harrows