A cultivator is a farm implement for stirring and pulverizing the soil, either before planting or to remove weeds and to aerate and loosen the soil after the crop has begun to grow. The cultivator usually stirs the soil to a greater depth than does the harrow. The cultivator is used in crop work or farming.

Small lightweight mechanical cultivators are used for gardening. Garden cultivators can be used to mix soils with manures and fertilizers in preparation for planting. They till the soil and convert soil lumps to a tilth. Different attachments can rotovate and plough the soil.

Contents

Field cultivators

Field cultivators are used to complete tillage operations in many different types of crop fields such as corn, soybeans, and wheat. This implement has many shanks mounted on the underside of a metal frame. The rear of this machine is also equipped with small narrow rods that smooth out the soil surface for easier travel when planting. These machines are pulled by tractors through the field and can vary greatly in size and shape. Some of these implements are as small as 10 feet (3 m) wide and some are large and can be 60-80 feet wide. Picking the correct size greatly depends on the size of tractor owned by the farmer.

  Row crop cultivators

Row cultivators have a slightly different design than field cultivators. Instead of many rows of shanks for the purposes of preparing a seedbed, a row cultivator has one row of shanks or tools. The main function of this implement is to control weeds after the weeds have grown to 4-8" tall. The implement has gauge wheels located near the shanks that ensure proper tillage depth. The use of this machine has declined greatly since the use of herbicides has become a widespread practice among farmers in developed countries. Using row crop cultivators is still widely used in organic farming. This type of farming does not use any pesticides and row cultivating is an important tool that ensures good yields. This practice is also used in developing countries where herbicides are not widely available as they are in developed countries. These cultivators have sizes of four, eight, twelve, and sixteen rows.

  Uses and configurations

There are many different sizes and configurations of field cultivators and row crop cultivators. Choosing which type is best for a particular farm depends on many different factors. Some of these factors include farm size, the size of tractor available to pull the implement, and what types of crops are included in the farming operation. The main functions of the field cultivator is to prepare a proper seedbed for the crop that is going to be planted, burry crop residue in the soil which helps to warm the soil before planting, control weeds, and mix and incorporate the soil to ensure the growing crop has enough water and nutrients to grow well during the growing season. A proper seedbed is important for the seed to imbibe water and to germinate properly. Weed control is the main function of the row crop cultivator. Most field cultivators are raised and lowered and have their depth controlled by one or many hydraulic cylinders. Row crop cultivators are usually raised and lowered by a three point hitch and its depth is controlled by gauge wheels. Many of the implements are equipped with hydraulic wings that fold up that makes road travel much easier and safer.

  Sizing

When determining the size of cultivator needed for a particular farming operation, you need to first determine how much horsepower it takes to pull the implement and then compare that to horsepower capabilities of tractors available on the farm. To do this, you first need to determine how many pounds of force are required to pull the implement through the soil. The following equation is used to determin this:

D=F_i[A+B(S)+C(S)²]WT

where:

D is implement draft (lbf)

F is a dimensionless soil texture adjusment parameter

i = 1 for fine, 2 for medium, and 3 for course textured soils

A, B, and C are machine specific parameters

S is field speed (mile/hr)

W is machine width in ft or number of tools

T is tillage depth (in) for major tilage tools and dimensionless for minor tillage tools and seeding implements

A table with F, A, B, and C parameters can be found in the references section under Agriculture Machinery Management Data.

Once the answer is generated it will be in terms pounds and needs to be converted into an answer in terms of horsepower. To do this, complete the following equation:

(D(lbf) x S(ft/min))/33,000(ft·lbf/min) Multiply D x S first and then divide by 33,000 to convert the answer to horsepower.

Another concept that needs to be considered to compute an accurate answer is tractive efficiency.

Tractive efficiency=power at the drawbar divided by the power at the axle.

Most tractive efficiencies are between 70% and 80%. If the answer found above is multiplied by the tractive efficiency as a decimal you will find the HP that is actually available at the drawbar.

The last step is to simply compare the HP requirement of the field cultivator to the HP capabilities of the tractors that are part of the farming operation.

Sizes of field cultivators rangle from 20-60 feet wide. Most row cultivators come in sizes of 4, 8, 12, or 16 rows of shanks.

  Producers of cultivators used in row crop agriculture

Almost every type of an agriculture machinery producer has some variation of the field cultivator in their production line. Not all companies produce row crop cultivators simply because they are not as widely used as they have been in the past. Some of these companies include Case New Holland, John Deere, and Massey Ferguson just to name a few. Each of these companies have different styles of designing and manufacturing these implements.

  Safety

Agriculture in the United States is one of the most hazardous occupations a person can have. When using a cultivator of any size, safety needs to be considered at all times. The most care needs to be taken when traveling from field to field. Many cultivators are so large it can be difficult for the driver to see behind them. Extra care needs to be taken by the farmer to make sure that they ensure safety. Drivers around these types of farm machinery also need to be careful to not crowd the machine or try and pass when it is unclear. Also, almost all cultivators use some sort of hydraulic power. Hydraulic power is usually a safe and useful form of power, but problems can arrise if the proper precautions are not taken. Some hazards that can arise in the field are such things as hooking the implement in a fence line or on a tree. Both of these situations can cause damage to the tractor as well as to the cultivator.

  Operation of field and row crop cultivators

Operating these two implements can be somewhat challenging without training and experience. Field cultivators need to be placed at the proper as to not rip up the soil and to prepare a good seedbed for the seed. This depth will vary with implement and trial runs will need to be performed to obtain the correct depth. When turning around at the end of fields the implement should be raised but still left in the ground to avoid compaction on the end rows of the field. Proper speed needs to be considered of the tractor as to not damage the tractor or the implement. Concentration needs to be even greater for the row cultivator. If straight driving is not maintained the row crops will be destroyed by the teeth of the implement. In this operation, the implement is lifted completely out of the ground as to not destoy the plants on the end rows. Speed of travel is also reduced to ensure that the minimum amount of plants are destroyed when preforming this operation.

  Problems with using field cultivators in some field conditions

Field cultivators can have a difficult time working properly if fields conditions are not at the proper levels. These field conditions can be such things as wet soil, great amount of residue on the soil surface, and rocky soil. Wet soil and increased residue can cause the implement to become "plugged" up and require the area to be re-tilled. Rocky soil can cause the shanks on the under side of the machine to break off. The can lead to running over it with another machine and causing a flat tire or the shank can be taken in by the combine harvester and cause great damge to the internal working parts. Increased care needs to be taken when operating in field conditions such as these. Decreased depth of tillage may help solve these problems. Going over the soil with another tillage implement first such as a plow or a ripper can help avoid the residue clogging problems.

 

The plough (American spelling: 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. The primary purpose of ploughing is to turn over the upper layer of the soil, bringing fresh nutrients to the surface, while burying weeds and the remains of previous crops, allowing them to break down. It also aerates the soil, and allows it to hold moisture better. In modern use, a ploughed field is typically left to dry out, and is then harrowed before planting.

Ploughs were initially pulled by oxen, and later in many areas by horses. In industrialised countries, the first mechanical means of pulling a plough used steam-power (ploughing engines or steam tractors), but these were gradually superseded by internal-combustion-powered tractors. In the past two decades plough use has reduced in some areas (where soil damage and erosion are problems), in favour of shallower ploughing and other less invasive tillage techniques.

Ploughs are even used under the sea, for the laying of cables, as well as preparing the earth for side-scan sonar^{[citation needed]} in a process used in oil exploration.

The early German word before sound-shift is plug and in Old Prussian plugis. After the German sound shift (p = pf) it became the modern German word Pflug.

  History of the plough

  Hoeing

When agriculture was first developed, simple hand-held digging sticks or hoes would have been used in highly fertile areas, such as the banks of the Nile where the annual flood rejuvenates the soil, to create furrows wherein seeds could be sown. In order to regularly grow crops in less fertile areas, the soil must be turned to bring nutrients to the surface.

  Scratch plough

Main article: Ard (plough)

The domestication of oxen in Mesopotamia and by its contemporary Indus valley civilization, perhaps as early as the 6th millennium BC, provided mankind with the pulling power necessary to develop the plough. The very earliest plough was the simple scratch-plough, or ard, which consists of a frame holding a vertical wooden stick that was dragged through the topsoil (still used in many parts of the world). It breaks up a strip of land directly along the ploughed path, which can then be planted. Because this form of plough leaves a strip of undisturbed earth between the rows, fields are often cross-ploughed at right angles, and this tends to lead to squarish fields^[1] In the archeology of northern Europe, such squarish fields are referred to as "Celtic fields".

  Crooked ploughs

Main article: Aratrum

The Greeks apparently introduced the next major advance in plough design; the crooked plough, which angled the cutting surface forward, leading to the name. The cutting surface was often faced with bronze or (later) iron. Metal was expensive, so in times of war it was melted down or forged to make weapons – or the reverse in more peaceful times. This is presumably the origin of the term "beat your swords to ploughshares".

  Mouldboard plough

A major advance in plough design was the mouldboard plough (American spelling: moldboard plow), which aided the cutting blade, the coulter, with a wedge-shaped surface, the mouldboard, When dragged through a field, a slice of the topsoil on one side of the cut was lifted up and flipped over by the mouldboard, falling beside the plough. This not only opened up the strip directly below the mouldboard, but also covered the previous strip beside it, thereby turning over a much wider strip in one pass: the classic furrow. This greatly reduced the amount of time needed to prepare a field, and as a consequence, allowed a farmer to work a larger area of land. In addition, the resulting pattern of low (under the mouldboard) and high (beside it) ridges in the soil formed water channels, allowing the soil to drain. In areas where snow buildup is an issue, this allows the soil to be planted earlier as the snow runoff is drained away more quickly.

Parts of a mouldboard plough: There are 5 major parts of a mouldboard plough

1. Mouldboard
2. Share
3. Landside
4. Frog
5. Tailpiece

A runner extending from behind the share to the rear of the plough controls the direction of the plough, because it is held against the bottom land-side corner of the new furrow being formed. The holding force is the weight of the sod, as it is raised and rotated, on the curved surface of the mouldboard. Because of this runner, the mouldboard plough is harder to turn around than the scratch plough, and its introduction brought about a change in the shape of fields—from mostly square fields into longer rectangular "strips" (hence the introduction of the furlong).

An advance on the basic design was the ploughshare, a horizontal cutting surface mounted on the tip of the mouldboard introduced by the Celts in Britain around 4000 BC. Early mouldboards were basically wedges that sat inside the cut formed by the coulter, turning over the soil to the side. The ploughshare spread the cut horizontally below the surface, so when the mouldboard lifted it, a wider area of soil was turned over.

Heavy ploughs

In the basic mouldboard plough the depth of the cut is adjusted by lifting against the runner in the furrow, which limited the weight of the plough to what the ploughman could easily lift. This limited the construction to a small amount of wood (although metal edges were possible). These ploughs were fairly fragile, and were unsuitable for breaking up the heavier soils of northern Europe. The introduction of wheels to replace the runner allowed the weight of the plough to increase, and in turn allowed the use of a much larger mouldboard faced in metal. These heavy ploughs led to greater food production and eventually a significant population increase around 600 a.d.

Despite a number of innovations, the Romans never achieved the heavy wheeled mouldboard plough. The first indisputable appearance after the Roman period is from 643, in a northern Italian document^[2]. Old words in connected with the heavy plough and its use appear in Slavic, suggesting possible early use in this region^[3]. It appears to have been developed independently in Han Dynasty China, around 100 BC. The general adoption of the mouldboard plough in Europe appears to have accompanied the adoption of the three-field system in the later eighth and early ninth centuries, leading to an improvement of the agricultural productivity per unit of land in northern Europe.^[4]

Research by the French historian Marc Bloch in medieval French agricultural history showed the existence of names for two different ploughs, "the araire was wheel-less and had to be dragged across the fields, while the charrue was mounted on wheels".^[5]

  Improved designs

The basic plough with coulter, ploughshare and mouldboard remained in use for a millennium. Major changes in design did not become common until the Age of Enlightenment, when there was rapid progress in design. The Dutch are credited with the introduction of newer shapes for the mouldboard in the 1600s, although these shapes were known earlier in China and may have been discovered by the Dutch while there.^[6]

Joseph Foljambe in Rotherham, England, in 1730 used these new shapes as the basis for the Rotherham plough, which also covered the mouldboard with iron.^[7] Unlike the heavy plough, the Rotherham (or Rotherham swing) plough consisted entirely of the coulter, mouldboard and handles. It was much lighter than conventional designs and became very popular in England. It may have been the first plough to be widely built in factories.

James Small further improved the design. Using mathematical methods he experimented with various designs until he arrived at a shape cast from a single piece of iron, the Scots plough. This was again improved on by Jethro Wood, a blacksmith of Scipio, New York, who made a three-part Scots Plough that allowed a broken piece to be replaced. In 1837 John Deere introduced the first steel plough; it was much stronger than iron designs that it was able to work the soil in areas of the US that had earlier been considered unsuitable for farming. Improvements on this followed developments in metallurgy; steel coulters and shares with softer iron mouldboards to prevent breakage, the chilled plough which is an early example of surface-hardened steel^[8], and eventually the face of the mouldboard grew strong enough to dispense with the coulter.

  Single-sided ploughing

The first mouldboard ploughs could only turn the soil over in one direction (to the right), as dictated by the shape of the mouldboard, and so the field had to be ploughed in long strips, or lands. The plough was worked clockwise around each land, ploughing the long sides alternately, gradually moving soil from the sides to the centre line of the strip. If the strip was in the same place each year, the soil built up into a ridge, creating the ridge and furrow effect seen in some ancient fields.

  Turnwrest plough

The turnwrest plough allows ploughing to be done to either side. The mouldboard is removable, turning to the right for one furrow, then being moved to the other side of the plough to turn to the left (the coulter and ploughshare are fixed). In this way adjacent furrows can be ploughed opposite directions, allowing ploughing to proceed continuously across the field, thus avoiding the ridge and furrow topography.

  Reversible plough

The reversible plough has two mouldboard ploughs mounted back-to-back, one turning to the right, the other to the left. While one is working the land, the other is carried upside-down in the air. At the end of each row, the paired ploughs are turned over, so the other can be used. This returns along the next furrow, again working the field in a consistent direction.

  Riding and multiple-furrow ploughs

Early steel ploughs, like those for thousands of years prior, were walking ploughs, directed by the ploughman holding onto handles on either side of the plough. The steel ploughs were much easier to draw through the soil that the constant adjustments of the blade to react to roots or clods was no longer necessary, as the plough could easily cut through them. It was not long after that the first riding ploughs appeared. On these, wheels kept the plough at an adjustable level above the ground, while the ploughman sat on a seat where he would have earlier walked. Direction was now controlled mostly through the draught team, with the handles allowing fine adjustments. This led very quickly to riding ploughs with multiple mouldboards, dramatically increasing ploughing performance.

A single draught horse can normally pull a single-furrow plough in clean light soil, but in heavier soils two horses are needed, one walking on the land and one in the furrow. For ploughs with two or more furrows, one or more horses have to walk on the loose ploughed sod -- and that makes hard going for them, and treads the newly ploughed land down. It is usual to rest such horses every half hour for about ten minutes.

Amish farmers tend to use a team of about seven horses or mules when spring ploughing and as Amish farmers often help each other plough, teams are sometimes changed at noon. Using this method about 10 acres can be ploughed per day in light soils and about 2 acres in heavy soils.

  Steam ploughing

The advent of the mobile steam engine allowed steam power to be applied to ploughing from about 1850. In Europe, soil conditions were too soft to support the weight of the heavy traction engines. Instead, counterbalanced wheeled ploughs, known as balance ploughs, were drawn by cables across the fields by pairs of ploughing engines which worked along opposite field edges. Balance ploughs had a set of right-handed ploughs for one direction, and left-handed ploughs for the other, one set being kept tipped out of the ground when the other was in use (like the reversible plough, but swinging in a different direction). The man credited with the invention of the ploughing engine^[clarify], in the mid nineteenth century, was John Fowler, an English agricultural engineer and inventor.

In America the firm soil of the Plains allowed direct pulling with steam tractors, such as the big Case, Reeves or Sawyer Massey breaking engines. Gang ploughs of up to fourteen bottoms were used. Often these big ploughs were used in regiments of engines, so that in a single field there might be ten steam tractors each drawing a plough. In this way hundreds of acres could be turned over in a day. Only steam engines had the power to draw the big units. When internal combustion engines appeared, they had neither the strength nor the ruggedness compared to the big steam tractors. Only by reducing the number of shares could the work be completed.

  Stump-jump plough

The Stump-jump plough was an Australian invention of the 1870s, designed to cope with the breaking up of new farming land, that contains many tree stumps and rocks that would be very expensive to remove. The plough uses a moveable weight to hold the ploughshare in position. When a tree stump or other obstruction such as a rock is encountered, the ploughshare is thrown upwards, clear of the obstacle, to avoid breaking the plough's harness or linkage; ploughing can be continued when the weight is returned to the earth after the obstacle is passed.

A simpler system, developed later, uses a concave disc (or a pair of them) set at a large angle to the direction of progress, that uses the concave shape to hold the disc into the soil – unless something hard strikes the circumference of the disk, causing it to roll up and over the obstruction. As the arrangement is dragged forward, the sharp edge of the disc cuts the soil, and the concave surface of the rotating disc lifts and throws the soil to the side. It doesn't make as good a job as the mouldboard plough (but this is not considered a disadvantage, because it helps fight the wind erosion), but it does lift and break up the soil.

  Modern ploughs

Modern ploughs are usually multiple reversible ploughs, mounted on a tractor via a three-point linkage. These commonly have between two and as many as seven mouldboards – and semi-mounted ploughs (the lifting of which is supplemented by a wheel about half-way along their length) can have as many as eighteen mouldboards. The hydraulic system of the tractor is used to lift and reverse the implement, as well as to adjust furrow width and depth. The ploughman still has to set the draughting linkage from the tractor so that the plough is carried at the proper angle in the soil. This angle and depth can be controlled automatically by modern tractors.

  Specialist ploughs

  Chisel plough

The chisel plough is a common tool to get deep tillage with limited soil disruption. The main function of this plough is to loosen and aerate the soils while leaving crop residue at the top of the soil. This plough can be used to reduce the effects of compaction and to help break up ploughpan and hardpan. Unlike many other ploughs the chisel will not invert or turn the soil. This characteristic has made it a useful addition to no-till and limited-tillage farming practices which attempt to maximise the erosion-prevention benefits of keeping organic matter and farming residues present on the soil surface through the year. Because of these attributes, the use of a chisel plough is considered by some to be more sustainable than other types of plough, such as the mouldboard plough.

The chisel plough is typically set to run up to a depth of eight to twelve inches (200 to 300 mm). However some models may run much deeper. Each of the individual ploughs, or shanks, are typically set from nine inches to twelve inches apart. Such a plough can encounter significant soil drag, consequently a tractor of sufficient power and good traction is required. When planning to plough with a chisel plough it is important to bear in mind that 10 to 15 horsepower (7 to 11 kW) per shank will be required.

  Ridging plough

A ridging plough is used for crops, such as potatoes, which are grown buried in ridges of soil. A ridging plough has two mouldboards facing away from each other, cutting a deep furrow on each pass, with high ridges either side. The same plough may be used to split the ridges to harvest the crop.

  Mole plough

To carry out arable farming on wet land, underdrainage is needed. Traditionally this meant digging many deep trenches across the fields, and burying drains in these. The mole plough allows underdrainage to be installed without trenches. It is a very deep plough, with a torpedo-shaped cylindrical tip, and a narrow blade connecting this to the body. When dragged through the ground, it leaves a cylindrical channel deep under the ground, and this acts as a drain. Modern mole ploughs may also bury a flexible perforated plastic drain pipe as they go, making a more permanent drain.

  Use of the mouldboard plough

In modern use, the mouldboard plough was used for three reasons:-

• Foremost was the control of weeds. In this function, mouldboard ploughing is very successful, a farmer can control weed growth with far fewer herbicides by using this technique than is otherwise possible with any other method, aside from hand weeding, which is labour-intensive and not practical for large operations.
• To break up the soil for planting.
• To warm the soil for planting.

Only the first reason for mouldboard ploughing really paid off. Most plants require little soil agitation to germinate, so breaking up soil is unnecessary beyond what a planting implement accomplishes on its own. Soil warming is also unnecessary beyond two or three inches below the surface, therefore bringing black fresh soil which heats more quickly and more deeply after the final frost of the year is unneeded.

  Problems with mouldboard ploughing

Mouldboard ploughing has become increasingly recognised as a highly destructive farming practice with the possibility of rapidly depleting soil resources. In the short term, however, it can be successful, hence the reason it was practised for such a long time. A field that is mouldboarded once will generally have an extraordinary one time yield as the larvae of pests and seed from weeds are buried too deeply to survive. After the first harvest, however, continued mouldboarding will diminish yields greatly.

The diminishing returns of mouldboard ploughing can be attributed to a number of side effects of the practice:-

• Foremost is the formation of hardpan, or the calcification of the sub layer of soil. In some areas, hardpan could once be found so thick it could not be broken up with a pickaxe. The only effective means of removing hardpan is using a "ripper", or chisel plough, which is pulled through the hardpan by an extremely powerful and costly tractor. Obviously, this layer eventually becomes impenetrable to the roots of plants and restricts growth and yields. This layer also becomes impenetrable to water, leading to flooding and the drowning of crops.
• Mouldboard ploughing rapidly depletes the organic matter content of soil and promotes erosion; these two problems go hand in hand. As soil is brought to the surface, the root structure of the previous harvest is broken up, and the natural adhesion of soil particles is also lost; though loose soil appears good for plant germination (and it is), this loose soil without cohesion is highly susceptible to erosion, multiplying the rate of erosion by several factors compared to a non-mouldboarded plot. This increased rate of erosion will not only outpace the rate of soil genesis but also the replacement rate for organics in the soil, thus depleting the soil more rapidly than normal.
• Mouldboard ploughing leads to increased soil compaction and loss of pore space within the soil. Soil is a bit like a bucket full of balls filled with sand. Each ball represents a cohesive particle of soil, and when stacked the balls leave a great deal of air space, required for healthy root growth and proper drainage. Mouldboarding so disturbs the soil that it breaks these balls and releases their contents. When this happens, the much smaller particles that are within the larger particles are released and pore space diminishes, leading to hard compacted soil that floods easily and restricts root growth.

  Soil erosion

One negative effect of ploughing is to dramatically increase the rate of soil erosion, both by wind and water, where soil is moved elsewhere on land or deposited in bodies of water, such as the oceans. Ploughing is thought to be a contributing factor to the Dust Bowl in the US in the 1930s. Alternatives to ploughing, such as the no till method, have the potential to limit damage while still allowing farming.

  Plough parts

• Frame
• Frog
• Share (also called a plowshare or ploughshare)
• Mouldboard
• Runner
• Landside
• Shin
• Trashboard
• Handles
• Hitch
• Knife or coulter

On modern ploughs and some older ploughs, the mouldboard is separate from the share and runner, allowing these parts to be replaced without replacing the mouldboard. Abrasion eventually destroys all parts of a plough that contact the soil.

 

This article is about the agricultural tool. For other meaning, see Harrow (disambiguation)

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In agriculture, a harrow is an implement for cultivating the surface of the soil. In this way it is distinct in its effect from the plough, which is used for deeper cultivation. Harrows were originally horse-drawn. In modern practice they are almost always tractor-mounted implements, drawn after the tractor, either trailed, or mounted on the three-point linkage..

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 and lumps of soil and to provide a finer finish, a good tilth or soil structure that is suitable for seeding and planting operations. Harrowing may also be used to remove weeds and to cover seed after sowing.

Chain harrowing may be used on pasture land to spread out dung, and to break up dead material (thatch) in the sward. Similarly in modern 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.

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 disks, teeth, linked chains or other means of cultivation. In the colder climates the commonest types are the disk harrow, the chain harrow, the tine harrow or spike harrow and the spring tine harrow. Chain harrows are often used for lighter work such as levelling the tilth or covering seed, while disk harrows are typically used for heavy work, such as following ploughing to break up the sod. 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.

A drag is a heavy harrow.

In Europe, harrows were first used in the early Middle Ages.

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The following text is taken from the Household Cyclopedia 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 horses 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, 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."

 

A rice transplanter is a specialized transplanter fitted to transplant rice seedlings onto paddy field.

Although rice is grown in areas other than Asia, rice transplanters are used mainly in East, Southeast, and South Asia. This is because rice can be grown without transplanting, by simply sowing seeds on field, and farmers outside Asia prefer this fuss-free way at the expense of reduced yield.

A common rice transplanter comprises:

• a seedling tray like a shed roof on which mat type rice nursery is set;
• a seedling tray shifter that shifts the seedling tray like a carriage of typewriters; and
• plural pickup forks that pick up a seedling from mat type nursery on the seedling tray and put the seedling into the earth, as if the seedling were taken between human fingers.

Machine transplanting using rice transplanters requires considerably less time and labor than manual transplanting. It increases the approximate area that a person can plant from 700 to 10,000 square metres per day.

However, rice transplanters are considerably expensive for almost all Asian small-hold farmers. Rice transplanters are popular in industrialized countries where labor cost is high, for example in South Korea.

Rice transplanters were first developed in Japan in 1960s, whereas the earliest attempt to mechanize rice transplanting dates back to late 19th century. [1] In Japan, development and spread of rice transplanters progressed rapidly during 1970s and 1980s.