Cover Image
close this book Animal traction
View the document About this manual
View the document About the author
View the document Acknowledgments
close this folder 1. Introduction
View the document What is animal traction?
View the document History of animal traction
View the document Why use animal traction?
View the document Some considerations
View the document How can animal traction be used?
View the document Before beginning: what do you need to know?
close this folder 2. Draft animal selection
View the document Popular draft animals
View the document Determining power requirements
View the document General rules concerning power requirements
View the document Method for determining size of the hitch
View the document Determining weights of animals
View the document Selection of individual draft animals
View the document Conformation
View the document Temperament
close this folder 3. Animal husbandry
View the document Sheller
View the document Nutrition
View the document Grooming
View the document Minor medical problems and first aid
close this folder 4. Training draft animals
View the document Before training begins
View the document General comments on training procedure
View the document Training cattle
View the document Program for training cattle
View the document Training horses, donkeys and mules
View the document Program for training horses, donkeys and mules
close this folder 5. Yokes and harnesses
View the document Yokes and harnesses for cattle
View the document Yokes and harnesses for horses, donkeys and mules
View the document How to harness a horse, donkey or mule
View the document Steering systems
View the document Breeching harness
close this folder 6. Hitches
View the document Safety rules
View the document Implement hitches
View the document Vehicle hitches
View the document 7. Field operations and implements
close this folder 8. Economic and technical assistance
View the document Farm planning assistance
View the document Equipment options
View the document Credit for equipment
View the document Credit for animals
View the document Procedures and controls
close this folder 9. Animal traction extension
View the document Extension education
View the document Appendix A: Animal power
close this folder Appendix B: Animal nutrition
View the document Energy needs: bovine animals
View the document Energy needs: equine animals
View the document Nutrient needs of draft animals: protein, minerals, vitamins
View the document Feeds and feed composition
View the document Calculating a ration
View the document Recommended rations and feeding practices
close this folder Appendix C: Disease recognition and control
View the document Parasites and parasitic disease
View the document Appendix D: Workshop and spare parts inventory
View the document Appendix E: Animal traction instruction forms
View the document Appendix F: Animal breeds used for power
View the document Bibliography
View the document Resources
View the document GIossary

7. Field operations and implements

Animal traction can be used to accomplish a variety of operations related to crop production. Operations which loosen and improve the soil where crops are grown are called tillage operations; plows, harrows, weeders, cultivators and ridgers are tillage implements. Other field operations include skidding (clearing fields of logs and brush), planting, and harvesting.

Tilling is any process that loosens the soil where crops are grown. The work may be done by hand, using hoes, or with animal or engine-powered equipment. Tilling improves soil structure and helps crops root and grow.

Primary tillage refers to operations which loosen very compact soil. Hilling (mounding) or ridging by hand, plowing with a moldboard plow, or breaking land with an ard or discing plow are examples of primary tillage operations. They are used on virgin land (never cultivated), fallow land (used, but since overgrown with grass or forest), or on fields which have-hardened during winter or off-season months.

Later operations, such as harrowing, clod crushing, weeding (cultivating), and ridging are forms of secondary tillage. These operations are used to prepare the seedbed or improve the soil where crops are maturing.

Clearing Fields With Animal Power

Animals can be used to clear fields of fallen trees or other debris that will interfere with plowing. Skidding is the process of dragging a log on the ground. Bobsledding is similar, but one end of the log is lifted onto a sled to reduce friction and make pulling easier.


Skidding a Log


Bobsled

Standard procedure is to attach the chain to the log or sled and then drive the team into a position where the chain can be hitched to its doubletree, or to a drawchain dragged from a yoke. When moving the load, the driver should stand to the side of the log or sled and watch out for stones, debris, or variations in slope that can throw or roll the end of the log toward him/her, causing injury.

Plowing

Plowing is most often done with a moldboard plow. This is a tool that loosens earth by cutting a slice and turning it partially over so that air and water reach the area where plants root, often referred to as the root zone. The soil is cut by a blade, called a share. The soil is lifted and turned by a moldboard. The cut made by a plow is called a furrow and the soil thrown is called a furrow slice. When the moisture level of the soil is right (damp, not sticky), the furrow slice curls off the upper portion of the plow moldboard and is thrown into the side of the adjacent slice.


Moldboard Plow

Source: Centre d'études et d'expérimentation du machinisme agriculture trocal (CEEMAT). Manuel de Culture avec Traction Animale. 1968. CEEMAT, Parc de Tourvoie, 92160 Antony, France.


Turning Over the Furrow Slice

Source CEEMAT, On. Cit.

The furrow slice loses its internal tightness as it is tumbled, jarred, and then squeezed between the moldboard's tail and the adjacent slice. Although the slice appears to hold its form, separatione between soil particles permit entrance of air and water, and later make it easy for seedling roots to branch out. Clumps and clods may remain after plowing, but these can be broken afterwards with harrows or other equipment.

Width of the slice varies with the length of the share. Depth is controlled by setting the wheel or by th length of the chain between the yoke and the implement; an average depth is 10-20 cm.

Effects of Plowing

Good plowing stimulates plant growth by opening the compact upper surface of the soil so roots can develop quickly, taking nutrients, water, and oxygen from the soil. Moisture is absorbed easily, seeping down to deeper areas where it can act as a reserve during dry periods.

Plowing also serves to turn under weeds and organic surface material that becomes valuable fertilizer. Good plowing tilts the furrow slice so decaying material is spread evenly through the loose soil. As oxygen and water penetrate and as sun dries exposed roots, the material decays and provides nutrients for the crop.

Plowing done after a crop is harvested is called backplowing. Stubble and surface debris is turned back into the soil where it decomposes and returns nutrients to the soil. If the plowing was deep, it is followed in the spring with light backplowing or scarification. Back plowing to a depth different from initial plowing prevents fixation of the pan ("hard pan") and aids maintenance of a healthy soil profile.


Effects of depth of plowing relative to width of furrow on the final position of the furrow slice:

1) Unbroken layer of sod between the seedbed and pan. Bonding is slow.

2) Too much contact between furrow slices. The bed stays rigid longer. It does not settle.

3) Upper edge of furrow slices can be readily worked down to a seedbed without the interference of sod. Later packing and preparation should break down the lower edge of the furrow slice and bring topsoil into con tact with subsoil.

Correct angulation of the plow slice can be achieved when the depth of plowing is about one-half the width of the furrow.


ARD (breaking plow, or chisel plow)

Source. Hopfen, Op. Cit.

Shallow tillage plows, which break the soil surface but do not turn it under, are called breaking plows, chisel plows, or arcs. They are used where short growing seasons and dry soil conditions make shallow plowing a desirable technique (typically in Africa's Sahelien and subsahelien zones). A breaking plow has no moldboard and hence no side draft; as a result it will hold a straight line when pulled by a single animal.

Adjusting the Plow

Draft tools can be adjusted to deliver the kind and quality of tillage farmers want, and minimize the effort required by the operator. Plow adjustment features include the adjustable wheel, the horizontal regulator, and the vertical regulator. In addition, handles on some plows can be adjusted according to the height of the operator.


Multi-Purpose Tool Frame (Arara brand)

Source: Dineur, Op. Cit.

Adjustments are better understood with experience as the operator learns the "feel" of the tool, how land is supposed to break over a ridger, or curl off a moldboard. Until then, an animal traction instructor can point out adjustments which minimize operator effort while maximizing tillage objectives. An instructor can adjust the equipment, demonstrate its use, and then let the farmer use it. Later, adjustments can be made that change the blade action and produce different results. In this way, the farmer learns about the performance range of the equipment through supervised, hands-on experience.

Depth of Plowing

Plow without wheel: Some plows have no wheel in front, and in these cases the depth of plowing depends on the length of the hitch, that is, the connection between the animal(s) and the load. Lengthening the hitch increases the depth of the plowcut. Shortening the hitch reduces the depth of the cut.

Adjustments are made by trial and error. If the objective is to plow a furrow 15 cm deep and the plow is working at 12 cm, lengthen the hitch by adding a few links to the drawchain where it connects to the front of the plow. If the cut is too deep, drop a few links.

If the team is pulling in harness rather than a yoke, regulate the length of the hitch by adding or dropping links on the short drawchain connecting the doubletree to the front of the plow. The adjustment can also be made on the traces, but each of four traces will have to be adjusted.

Plow with wheel: Plows with wheels are adjusted by raising or lowering the wheel in relation to the beam. If the wheel is high, or close to the beam, plowing will be deep. If it is low, far from the beam, plowing will be shallow.

The wheel is mounted on a shaft that slides up and down through a hole in the beam. To set the plowing depth, the operator slides the shaft up or down and locks it into place with a bolt (see plow diagram)

When the bottom of the wheel is even with the bottom of the plow, there is zero depth of tillage; the plow, if pulled, will ride on the surface. In order for the plow to descend, the shaft/wheel assembly must be raised so the wheel is closer to the beam.

Adjustments are usually made by trial and error, but a very precise adjustment can be made in this manner:

• put the plow on flat ground and steady it so the plow bottom is level and the beam parallel to the ground.

• loosen the bolt holding the shaft/wheel assembly to the beam and let the shaft slide down until the wheel hits the ground.

• decide how deep you want to plow and raise the wheel the same distance off the ground. If you want your furrows 12 cm deep, raise the shaft until the bottom of the wheel is 12 cm above the ground, and then lock the shaft in place.

Correct Line of Traction: Vertical Regulation

When a plow is cutting correctly, it works flat on the furrow bottom: the point of the share and the bottom of the heelpiece are level. This does not happen automatically. The operator usually has to make an adjustment called vertical regulation. The adjustment is made by raising or lowering the point where the drawchain meets the front of the plow.

On some plows, the drawchain hooks to a pin that slides through the beam and locks at various heights. On others, it hooks to a perforated bar welded to the front of the beam. These devices, and others like them, are called vertical regulators.

The adjustment is made by trial and error. After the wheel is set, the operator begins to cut a furrow. If the wheel presses hard into the ground leaving a deep tracemark, and/or if the plow snags and bounces, even when there are no roots, the chain is too high. If the wheel lifts off the ground and the plow tends to ride up to the surface, the chain is hitched too low.

Vertical regulation is correct when the plow bottom works flat. The plow glides smoothly, maintaining its depth. The wheel rolls easily and the beam is parallel to the ground. The operator doesn't have to help the plow maintain its digging plane by exerting pressure on the handles.

When this is happening, the drawchain will be riding on the-line of draft, or line of traction-an imaginary straight line that connects the point of draft (yoke clevis or hame draft) to the point of resistance. The point of resistance is located near the midpoint of the share/moldboard joint; it is the point where the plow meets the most resistance from the soil.


INCORRECT vertical adjustment: The plowpoint angles down, the heelpiece lifts up, the entire plow-bottom pitches down, causing snagging and wheel pressure. The operator has to keep pulling up or lifting the plow handles.


INCORRECT vertical adjustment: The plowpoint angles up, the heelpiece presses down, the plowbottom pitches up, causing the plow to ride to the surface. The operator has to keep pushing down on the plow handles.


CORRECT vertical adjustment: The plowpoint and the heelpieces are on the same level. The plowbottom works flat.

Width of Plowing: Horizontal Regulation

Width of plowing is established by positioning the drawchain on the horizontal regulator-a notched or perforated bar fixed to the vertical regulator. As the chain is moved toward the right end of the bar, the plow cuts a broader furrow. As it is moved to the left, it cuts a narrower furrow.

The plow is easiest to control when the chain is hooked to the hole in the center of the bar, or to the hole just right of center. When this hitch is made, the beam runs parallel to the furrow cut. The forces on the moldboard are very uniform and the plowman does nothing but balance the plow and help it around roots and stones. (Fig. A)


Width of Plowing: Horizontal Regulation

When broader or narrower cuts are made, the plowman must use more control. If the chain is hitched to the right, the plow will angle toward the unplowed land. The operator keeps it going straight by tipping it to the left, and the plow is bearing down slightly on the left handle. But if it's hitched all the way to the right, the share may not have a long enough edge to cut all of the furrow slice. In this case, the operator must develop enough speed and thrust to knock the whole slice over. A strong, steadypulling team is needed and the operator must keep constant pressure on the left plow handle. (Fig. B)

If the chain is hitched to the left of the regulator midpoint, the plow will cut a narrower furrow. The operator uses slight pressure on the right handle to keep the furrow uniform. If the chain is hitched all the way to the left, the plow will angle into the open furrow unless the operator compensates with manual effort. (Fig. C)

Aids for Plowing Heavy Vegetation

Some plows are equipped with a courter, a knife-like blade which is fixed to the beam in front of the moldboard. It extends downward so it pre-cuts roots and sod and makes it easier for the moldboard to turn the furrow slice.

If grass is very tall or vegetation heavy, it may stick up between the turned furrow slices and continue to grow. In these cases, pre-flatten it by attaching a heavy chain to the outermost hole of the horizontal regulator (or to the right-hand end of a singletree) and loop it back to the beam.

An alternative method is to stretch a heavy-gauge wire from the horizontal regulator to a point on the ground behind the moldboard. When plowing begins, the weight of the turning furrow slice puts tension on the wire and keeps it in position to flatten the oncoming grass. At the beginning of each furrow, the plow operator must stand on the end of the wire until the slice begins to turn over on top of it.


Use of Coulter and Aid Chain

Field Layout

A sturdy, well-trained pair of bulls can plow a hectare (ha) of clear, root-free land in four days. Farmers who learn to break the hectare into standard-size strips or parcels will know how much work their bulls can produce per day, and this knowledge will help them plan the labor effort of the family.

A practical work strip is 12 m wide and 50 m long. With this field layout animals will not tire and the driver will waste no time or energy turning the plow at the end of the row. If a plowteam turns four of these strips a day, it will have completed one-fourth hectare.

The recommended layout for plowing a one-hectare field is illustrated below. If no measuring ropes or chains are available, workstrips are laid out approximately 60 paces long (a pace = a normal walking step) and 15 paces across. At least four meters (5-6 paces) of unplowed land, or headland, must be left at the top and bottom of each strip to allow room for turns. Two meters of clear land should be left along the side of the first strip if the field is bordered by a forest; this space will be needed when the team weeds the outermost row. A central turnaround strip is used so that the team and driver do not have to make turns on already-plowed land.


Well-planned field showing use of central turnaround strip. The turnaround strip is plowed last.


Setting the Crown

This strip is plowed last.

Before plowing the first workstrip, mark the corners of the headlands, sidelands, and central turnaround strip. Then take eight paces along the inside of the headland and place a stake there. Put another stake opposite the first, and on the border of the turnaround strip.

The workstrip is plowed by making a series of clockwise passes (right-hand turns) around a ridge made between the two stakes. The ridge is called a crown. Plowing begins by setting the crown.

Steps to set crown:

• Place the plow just to the right of the first stake (A) and cut a shallow furrow to the opposite stake (B) (Fig. 1).

• Reverse the team and put the plow back into the furrow just made. Return to Point A, cutting the furrow a little deeper. The result is that you have made a well-defined trench whose sides are banked with loose soil (Fig. 2).

• Turn to the right and put the plowpoint next to the loose soil. Return to the opposite end of the field, throwing this soil back_into the trench. Then turn to the right and come back along the other side of the trench, throwing the rest of the loose soil in (Figure 3).

• Readjust the plow, setting the wheel so the moldboard will work at the full, desired depth. Then cut a furrow in the land just to the left of the filled trench. The new furrow slice will fold against the soil in the trench and partially cover it. On the return trip, more dirt will be thrown against it, and on top of it. The result will be a ridge of earth that will be slightly higher than the rest of the plowed field. This is the "crown".

• Correctly made, the crown is made of loosened, turned earth. Some plowmen make the crown simply by throwing a set of furrow slices over a center of hard, unplowed land. The result is that later, the plants in the rows either side of the crown do not have access to well-tilled soil.

Once the crown is set, plowing proceeds in a clockwise manner until the plowed strip is approximately 15 paces wide. Then stakes A and B are pulled out and placed eight paces to the right of the edge of the plowed land. The stakes mark the line where the plowman

sets a new crown and begins the next workstrip.

Concentric Plowing

A concentric pattern may be effective if plowing is expanded around a block made of two or three completed workstrips. However, a pattern that works inward toward an increasingly smaller square of unplowed land is not practical. Land is trampled with each turn, and when the central workstrips are plowed, there is no headland for turning.

Notes on Using the Plow

The following suggestions will be helpful to instructors teaching farmers to use the plow.

• Choose "easy" ground-an old field free of roots, rocks and trees. Plow one or two days after rain. During the dry season, farmers can practice on sandy or pebbly soils; however, these soils may be too loose or powdery to be plowed into uniform furrow slices.

• Make sure the plow is adjusted correctly. Set it to cut a shallow but well-defined furrow. Lower the handles if possible. Do not teach farmers about adjustments until they have the "feel" of a correctly working plow.

• In the beginning, walk beside the farmers and drive the bulls for them so they can concentrate on using the plow. When starting new strips, lead the bulls from the front so they do not veer. Remember that once the guide cuts are made, the bulls follow them quite easily.

• Do not let farmers push the plow or bear down on the handles, since this drives the plowshare into the ground and makes the animals' work harder. Advise them to stand erect; show them that their job is simply to balance and steer the plow. They can cut a broader slice by dipping the handles slightly to the right; they narrow the slice by dipping them to the left. Eventually the farmers will learn to feel roots and rocks as they come across the share and help the plow around them with these same dipping motions.

• Teach them to walk in the furrow and lean to the landside. If they walk on the high ground, they will tend to push their plow to the right and make unnecessarily narrow cuts. If they straddle the cut, they will tire from constantly stepping up and down.

• During a turn, farmers should lift the handles and wheel the plow like a wheelbarrow. If the plow is not equipped with a wheel, they lean it on its right and let it drag. They should not cut the headland (turning area) because it is time-consuming and makes footing difficult.

• If the team is working poorly, as may be the case with a new pair, let the farmer practice using a pair that pulls well and obeys commands. The demonstration pair is ideal for hands-on learning.

Harrowing

Harrowing is the process of smoothing and leveling a plowed field. The harrow breaks clods and works the tops of furrow slices into a fine, moisture-retaining bed where seeds germinate easily. Higher germination rates resulting from harrowing are explained by improved structure of the seedbed:

• it is better aerated

• it is moisture-retaining

• there is more contact between the seed and soil particles; large air pockets and clods are eliminated and seeds are easily covered

• some weeds are killed.

A further advantage of harrowing is that it breaks down the tubes or coils of earth which are the remnant of furrow slices, making it easier to use line tracers or mechanical seeders.

There are several major types of harrows. Spike-tooth harrows are wooden or metal frames studded with rows of pegs or teeth (tines). Spring-tooth harrows are much like cultivators, but they have more teeth and can work to greater depths. They are especially useful for pulling up vines, roots and stones; they require greater draft than spike-tooth harrows. Disc harrows work the soil to an even greater degree, slicing and partially turning the bed; they are highly effective in soil that is heavy, sticky, or broken into large, hard clods.

Spike-tooth harrows are useful in granular, lateritic soils or in sandy soils that have been plowed when slightly wet and then left to settle; they are pulled perpendicular to rows. In heavier soils it may be necessary to harrow parallel to the furrows and afterwards at angles to them.


Spike-Tooth Harrows

Source: Hopfen, Op. Cit.


Planker

Spike-tooth harrows can be made locally and at little cost. The frame must be sturdy and able to carry weights such as logs or rocks; the weights help hold the harrow down, preventing bouncing, jarring and poor penetration of teeth. In fields where stumps and protruding rocks can cause interference, wedge-shaped frames are used, or the operator guides the harrow using a rope or set of handles. Teeth should be long enough to work the top several inches of soil. They should have a pointed tip, and the shafts should be made and fitted so the leading edge cuts into the soil (teeth made from round iron should be hammered into a triangular or diamond shape).

An affordable, easily-made alternative to the disc harrow is the planker, or plank drag. Used in combination with a spike-tooth harrow, it works heavy soil into an excellent seedbed.

Line Tracing for Parallel Rows

Since animal traction can reduce the labor needed for primary tillage, farmers can increase the size of their fields. However, they run the risk of insufficient labor for hand-weeding the extra area, so mechanical weed cultivation of parallel rows becomes a necessity.

Parallel rows are established by scoring the seedbed with a marking device called a line tracer, and then planting along the scoremarks. As plants mature, farmers can weed (cultivate), fertilize, ridge, and in some cases harvest them using animal power. This would not be possible if interrow widths varied, as is often the case when sowers line up shoulder to shoulder and advance across the field planting the seeds. Variations as little as 10-15 cm would make mechanical maintenance of the crop impossible; animals would step on plants and blades or cultivator tines would sever roots each time the rows got closer.

A line tracer is a frame made of a handle and a crossbar and pulled by hand or animal power. The crossbar is equipped with moveable teeth. The teeth are set at intervals that correspond to the recommended row spacing for a particular crop. The operator makes a set of marks the length of the field, turns, sets the outermost tooth on the outermost line made during the previous pass, and then draws the tracer back across the field. This gives the sowers a visible mark by exposing the darker, moist soil just under the surface; if the operator gets too far ahead of the sowers, the lines will dry and be harder to see.

A tracer can be made of light, sturdy wood or bamboo and fitted with hardwood or metal teeth. The pole used for the crossbar must be of straight, uniform stock because a tapered pole is heavier on one end and will throw the tracer off balance when it is pulled. Teeth must be long enough to pass through the crossbar and accommodate considerable irregularity in the surface of the field. The center tooth must be long enough to pass through the crossbar and the handle; it is not removeable. Other teeth can be moved into various holes in the crossbar.


Relationship of parallel line-tracing to later weeding operation


Line Tracer

The bar and handle should be joined so the teeth travel perpendicular to the ground when the marker is used. To do this, fit the bar with teeth and have an assistant hold the bar on the ground in a working position. Then lay one end of the handle over the bar mid point and lift the free end so it is hip high (pulling position). Mark and join the two pieces so they fit at this angle.


Side view of handle crossbar joint showing how joint affects tooth penetration angle.

Line tracing for parallel rows has other advantages besides those already mentioned:

• It makes it easier to calculate densities and yields, and determine fertilizer requirements

• Drawing two sets of parallel lines perpendicular to each other provides intersects where seeds can be planted; later, crosscultivation is possible for both inter-row and intra-row weeds.

Parallel rows can also be made by planting along a stretched rope or string, or by using a mechanical seeder.

Mechanical Seeders

A mechanical seeder is a handor animal-drawn machine that cuts a shallow furrow in the seedbed and then deposits and covers seed. The advantage of seeders is that they drill seed at uniform depth and at regular intervals along the row, reducing seed loss and ensuring proper density. They are useful also because at planting time, manual labor may be involved in late soil preparation and early weeding operations as well as planting. With the help of mechanical seeders farmers can achieve desired seed densities without placing strains on labor. The main drawback of seeders is their relatively high cost.


Seed Drill or Seed Planter

Source: Food and Agriculture Organization of the United Nations

Mechanical Weed Control

In most cases, the farmer who uses animal power will plow and plant more ground than can be weeded by hand. Plants are no longer tended individually, but by the row. The weeding operation can be accompanied with a weeding sweep or with a cultivator.

Sweeps work at shallow depths, uprooting weeds and loosening soil between row crops. They come in various widths to accommodate various inter-row distances. Correct choice of blade and depth of work ensures that pruning of crop roots does not occur. Generally speaking, a 35-cm blade (350 mm) is suitable for rows spaced 60 cm apart, a 50-cm blade (500 mm) for rows 80 cm apart.

Sweeps


Weeding Sweeps


Sweep for Ridging Potatoes

Source: Dineur, Op. Cit.


Weeding peanuts with a sweep. Cross-section showing proximity of blade to peanuts.

The sweep has several functions:

• It scrapes a shallow furrow between rows, cutting or uprooting weeds in its path. In addition, it pushes some soil to the sides, covering weed seedlings growing between plants on the row.

• It builds a light bank of soil against the row. The soil helps shade and support roots of the plants, and also covers fertilizer distributed at the base of the plants.

• It loosens soil, improving aeration and moisture retention.

Timing is very important. Weeds must be killed before they compete with crops for soil nutrients and water reserves. The first weeding is performed as soon as weed seedlings appear between the crops. It is delicate work because crops are young and easily knocked over if too much soil is pushed to the sides.

Two adjustments are made to concentrate blade action on weeds:

• Bottom depth of work is determined by height of the wheel. Depth increases as the shaft/ wheel is raised.

Wheel Adjustment


Adjust wheel so that blade undercuts weed

• Intensity of work is determined by the position of the blade up or down in the slots at the base of the leg.


Figure


Weeding/Banking Operation

For early weeding (weeds at oneor two-leaf stage; crops young): set the blade in the lowest position in the slots. The blade will slice under weeds, dislodging their roots; weeds wilt and die. In this position, the blades will not push soil out of the furrow toward the crop (A).

For late weeding/light banking (large or creeping weeds; crops older with stronger stems): set the blade in the highest position in the slots. The blade face is then more vertical resulting in greater contact between the blade and the soil. Weeds are knocked over and soil is pushed to the sides where it can cover weeds growing near plant stems (B).

No horizontal regulation of the drawchain is necessary with sweeps because the blades are symmetrical and have no side draft.


Figure

Weeding with a sweep can be done by one animal if soil conditions do not create too high a traction effort. In heavy, wet, or very weedy soils, two animals may be needed. In this case, the height of the plants will determine the type of hitch used. A doubletree can be used if plants are very low, but if it hits the tops of the plants, the animals will have to wear a yoke. Donkeys can be placed in a yoke if the withers are protected with pads and collars (see page 85).

Weeding Muzzle

In some instances, it is necessary to muzzle an animal to keep it from eating the crop during the weeding operation. A muzzle can be made of rope or woven rafia (palm leaves). It is worn over the muzzle and fastened behind the horns (page 79). Equine animals wearing halters or bridles can usually be controlled by tugging on the rein opposite the direction of head movement.

Cultivators

Cultivating is the process of scratching, mixing or stirring the uppermost layer of earth. A cultivator can be used as a plow or weeding device or to break ridges and mounds left from the previous season. A typical, animal-drawn cultivating tool is a set of five flexible tines mounted on a toolframe; duckfoot shovels or chisel points are attached to the ends of the tines. Smaller cultivators have three tines, while larger ones may have up to 15 tines.

The cultivator, with its capacity to carry multiple tines with sweeps of varying widths, has several important uses:

As a plow-Cultivating is an alternative to plowing when time or soil conditions do not! permit use of a moldboard plow. This is often the case in semi-arid regions where crops must be planted soon after the first rains in order to mature. The cultivator's wide track allows quick tillage; its shallow stirring action provides a seedbed without pulverizing soil and creating the danger of erosion. Repeated cultivations, however, can lead to erosion.

Cultivators also are used for preparation of rice lands. The topsoil is stirred and later, the field is banked and flooded. Rice planted in 40-cm rows can be weeded with a single 25-cm shovel mounted on the cultivator frame, or with two shovels (a double shovel) spaced on either side of the row.


Three-Tooth Cultivator

Source: CEEMAT, Op. Cit.


Five-Tooth Cultivator

Source: Dineur, Op. Cit.

As a harrow-When used for harrowing, the cultivator is equipped with the maximum number of tines which are spaced and arranged so that clods are broken and soil worked into a finer seedbed. The operation is performed soon after plowing, when soil is moist and clods break apart easily; dry clods glance off the tines. Very heavy or root-bound clods catch between the tines and cause it to drag or float to the surface.

As a weeding device-Cultivators can be used as general purpose weeding tools. Though new antrac farmers may find this tool expensive and complicated, its versatility is an important feature. Agents should be able to demonstrate its potential.

Cultivators work at fairly shallow depths with a limited range of adjustment. If the wheel is too high (too close to the beam), the front tines work at a greater depth than the rear shovels which will assume a vertical pitch; the cultivator will skip, catch, and veer. When the wheel is too low, the shovel points will not penetrate and the operator will have to press very hard on the handles. Correct traction is achieved when all shovels run at the same depth.

As a leveler-The cultivator's considerable weight allows for the leveling of old ridges or mounds. In rain forest zones, hoe farmers plant a second crop soon after the harvest of the first. They weed the field, reshape the worn ridges by hand, and then plant a new crop in the stubble of the old. A cultivator can break up the ridges and stir in organic material simultaneously; when the new crop is established, the cultivator can perform a combined weeding/ridging operation.

In drier areas, mounds and ridges can be broken directly after the harvest or at the beginning of the new season. In the latter case, the soil may be loose enough after cultivating to permit effective preplant ridging. Otherwise, a moldboard plow and harrow would be used to level the field, crops would be planted on a flat seedbed and ridging would be done later, after the plants were growing.


Ridger with Adjustable Wings

Source: Dineur, Op. Cit.

Ridging

A ridger is a wedge-shaped shovel that throws equal amounts of dirt to the right and left of a central furrow. It is a popular tool because it is easy to use and because it quickly accomplishes the weeding/ridging operation required for most grain crops. Like the moldboard bottom, it is mounted on a special leg that bolts to the toolframe.

A ridger cuts a furrow between row crops, uprooting weeds and throwing soil right and left against the crops. The soil buries weeds growing at the base of the crop, and at the same time stabilizes the crop stem and helps it support the maturing fruit. It also covers organic or chemical fertilizer destributed along the row.

Ridging can be performed any time after the crop is established and won't be knocked over by the soil pushed against it. In many instances, early weeding is done with a sweep or cultivator and later weeding/ridging operations done with a ridger. Once the crop has developed a leafy canopy, the shade greatly reduces weed competition and further weeding becomes unnecessary.

Adjustments: To increase the amount of soil thrown, raise the shaft/wheel assembly or lengthen

the drawchain. Width of operation is controlled by position of the adjustable wings in relation to the ridger body; as the wings are lowered, soil is pushed further to the side.

No horizontal regulation is needed.

Ridging Tall Crops

In corn and sorghum that has grown too tall to allow clearance of a yoke, a single strong animal can be used to make rid"' animal is harnessed in a breastband, traces are fas a singletree, and the sing. hitched to a ridger.


Ridging an Established Crop


Single Animal Ridging Maturing Corn (1)


Single Animal Ridging Maturing Corn (2)

Primary Tillage With a Ridger

The ridger may be used for primary tillage where the land was plowed the preceding season. Farmers make ridges directly in unplowed soil and then plant. The operation is less time-consuming than plowing with a moldboard, but it has the disadvantage of burying hard soil under a relatively narrow crown of loose soil. The hard soil has less water storage potential than plowed soil; also, it interferes with fast rooting.

Ridging and Fertilizer

Chemical fertilizer can be spread along evenly-spaced trace lines made on a flat field and then

buried as the ridge is formed. The procedure is called pre-plant banding. The ridger can also be used to cover fertilizer applied to the top of an already-formed ridge.

Smaller Ridges

Small, closely-spaced ridges can be made by removing the ridger wings and using the ridger body alone. Used this way, the ridger is an effective tool for banking soil against peanut plants. A single animal usually can supply the power needed for this operation.


Pre-Plant Banding

Source: Dineur. Op.. Cit.


Banking Peanuts

Lifting Peanuts with a Sweep

Because peanuts grow underground, a carefully adjusted weeding sweep can be an effective harvesting device. A sweep adjusted to uproot peanuts is called a lifter. In theory, peanuts are planted early enough so that the soil still has humidity when the crop is harvested, since once the ground hardens, the stems holding the pods become brittle. They break when the soil is loosened and many peanuts are lost.

In practice, the ground is often hard or hardening by harvest time. As a result it is extremely important to adjust the lifter correctly. The operator sets it to slice under the root zone. The entire horizon of soil containing the peanuts is "lifted". As it is lifted, the soil is broken apart by the leg arm of the sweep. The peanuts will remain attached to the plant, but will have been freed from the hardening crust of earth. Afterwards, it is easy for workers to pull out the plants and pile them, upsidedown, so the pods dry in the sun.

A 30-40-cm V-sweep is well suited for the work; it is long enough to cut under the plant and stiff enough to remain level. Longer blades are more flexible, and in hard soil, set the blade in a slicing rather than a pushing position by fixing it in the lowest part of the slot on the leg (page 141).

Depth of work increases as the shaft/wheel assembly is raised and decreases as it is lowered. The blade must cut below the peanuts, but not so deep that it creates extra work for the team. Depth varies according to the variety of peanut and soil conditions, but generally falls within an 8-12 cm range. The nose of the blade should pass 2-3 cm under the plant; establish the proper depth of the cut by trial and error. To find out if the cut is too shallow, use a hoe to dig under an area where the lifter has been used. If there are peanuts, the cut was too shallow, and the wheel must be raised.

No horizontal regulation is necessary.

A strong team is needed for lifting because the work is at a deep level and the ground may be hard. When the lifting is done with oxen, the standard plow yoke is used. If the longer weeding yoke is used, the team veers when the blade hits a very hard pocket of earth. This occurs toward the top of hills and in portions of the field where the ground is raised or contains a high clay content.


Lifting Peanuts with a Sweep

The wedge-shaped three-animal hitch should be used if donkeys do the lifting. If four donkeys are used, the strongest pair is put in the back.

If the soil is not too hard, a cultivator can be used. The teeth are arranged in a tight wedge and the wheel is set close to the beam. The method is useful where peanuts have been sown on traditional wide ridges, since these ridges tend to be soft underneath and break apart easily. Where the crust is very hard, the flexible quality of the tines makes penetration difficult; once below the crust, the ends of the teeth (shovels) catch in hard pockets, jump, and drive the machine upward, making cutting depth difficult to maintain.