THE CEREAL CROP

Buyer's guide to scarifiers

HomeFARMING ZONESGuide to cereals and pasture >   You Are Here.

Better cereal yields and lower cost production

CHAPTER HEADING

SUMMARY

This is a practical guide to the use of shallow cultivation for seed bed
preparation and seeding. Shallow cultivation is essential for cereals after
medic in order to ensure regeneration. It is a low cost means of seeding
for cereal, grain legumes and vetches.

This chapter provides the economic justification for shallow cultivation.

Deep plough and cultivation is entrenched in the WANA region. The
technology is wasteful and costly.

This is an overview of deep ploughing and shallow cultivation.

YOU ARE HERE

Once the decision has been made to use shallow cultivation it is absolutely
essential to have the proper implements. These are simple and cheap. Their basic design principles are described.

Cultivation, hay production and rotations are the main methods of
controlling weeds in the WANA region. Herbicides have a role. Practical
problems are discussed.

The response of cereals to nitrogen fertiliser in the WANA region is erratic. This is explained and strategies developed to overcome the problem. Phosphate placement can also increase yield responses.

Mechanical harvesting is the main method of harvesting cereals in the
WANA region. The machines imported from Europe and North America
perform badly as they are designed for high yielding, damp crops.
Australian adaptations will improve efficiency in low to medium yielding
crops with short, brittle straw.

Even a modified harvester will not work efficiently on small farms, around
olive trees and with many types of cereal crops. The stripper is a genuine small scale machine suited to these conditions.

Using shallow cultivation will often require more weight on tractors. Why
and how?

Small farmers often employ contractors to carry out cultivation, seeding and
harvesting. This is expensive and various forms of group ownership provide
a low-cost alternative.

FOUR COMMON ROTATION ON THE GROUND IN THE WANA REGION

SEASON

CEREAL - FALLOW

CEREAL - MEDIC

(Traditional rotation)

CEREAL - VETCH

CEREAL - GRAIN
LEGUME.

AUTUMN

Cereal crop sown

Cereal crop sown

Cereal crop sown

Cereal crop sown

WINTER

Cereal crop grows

Cereal crop grows

Cereal crop grows

Cereal crop grows

SPRING

Cereal crop matures

Cereal crop matures

Cereal crop matures

Cereal crop matures

SUMMER

Cereal crop harvested
Stubble grazed by livestock

Cereal crop harvested
Stubble grazed by livestock

Cereal crop harvested
Stubble grazed by livestock

Cereal crop harvested
Stubble grazed by livestock

AUTUMN

Weeds germinate naturally

Medic regenerates from seed
produced 18 months earlier.
No cultivation of the land
required.

Land cultivated and sown to
vetch or similar forage
legumes.

Land cultivated and sown to
grain legume such as lentils or
chick peas.

WINTER

Weeds grazed. Low stocking rate.

Medic pasture grazed. High stocking rate.

Grazed or more often left for
hay.

Grain legumes grow.

SPRING

Land cultivated for fallow

Medic grazed. Pods produced
for future regeneration.

Cut for hay.

Grain legumes mature.

SUMMER

Bare soil vulnerable to
erosion.

Pods and stubble grazed.

Stubble grazed.

Harvested.

Stubble grazed.

AUTUMN

Cereal cycle begins again.

Cereal cycle begins again

Cereal cycle begins again

Cereal cycle begins again

 

Why scarifiers are needed for shallow cultivation?
 

* Adjusting deep cultivating implements to shallow depths.

Diagram 1 and 2    - The chisel.




 
 

    Diagram 1 shows the chisel being used at its design depth of 25 to 30 cm.

All the soil is cultivated to a depth of 20 to 25 cm. This is an adequate depth to cut off weeds.

The machine works efficiently.

    * Diagram 2 shows the chisel when it is adjusted to a depth of 10 cm. for shallow cultivation. The soil between the tines is not cultivated to an adequate depth to cut off weeds.

The exact depth of cultivation between the tines depends on the soil type and the soil conditions.

Established weeds between the tines are merely covered with soil.

They soon grow again through this soil.

They need to be pulled out of the soil by the tine, knocked around with a harrow and left on the surface to dehydrate.

    * Using wide points.

On some light textured soils (sand) it is possible to fit wide points to the chisel.

These will cut off the weeds between the tines. The chisel will work efficiently to kill weeds but it is still not an ideal implement.

If the tractor can pull the chisel at 25 to 30 cm depth it can pull a scarifier twice as wide at a depth of 10 cm.

Trying to pull the chisel twice as fast is not practicable. The force required for pulling implements through the ground at high speed increases more than the speed. Double the speed requires more than double the power.

High speed creates a more uneven seed bed.

    * Using wide points is not a practical solution on harder soil types.

The force required to make the wide points enter the soil and work at the correct angle is greater than the break away force of the tine.

That means the tine is working at an angle.

The point only half enters the soil.

The wide wings on the point do not cut off the weeds (they are not in the soil) and the farmer has achieved little more than the first attempt at cultivation with narrow points.

* The disc plough and the mouldboard plough.

    Exactly the same applies with these implements as the chisel.

The typical three disc linkage plough has three large discs offset to the angle of travel.

They are designed to work at a depth of 25 to 30 cm.

If one looks at the plough from the front one can see the same gaps between the discs as shown above with the tines of the chisel. At a depth of 20 cm or more this does not matter.

The gaps are still adequately cultivated through sideways fragmentation of the soil.

At a shallow depth (10 cm) this sideways fragmentation does not work and strips of poorly cultivated land occur between each disc.

    The same applies to the mouldboard plough.

This is a disc plough used for deep ploughing. In the WANA region the most common plough is the three disc linkage plough shown below.

The solution - closer tine/disc/mouldboard spacing

     The answer to the problem of poor cultivation at shallow depths is to drop another tine or disc or mouldboard into the gap.

This will cultivate all the soil at a shallow depth. Weeds will be killed but at much less cost than deep cultivation.

This is a disc plough designed for shallow cultivation. Note that there are 14 discs for a 3 m width. A similar 3 m disc plough designed for deep ploughing had only 9 discs.

    All these solutions have been used for shallow cultivation but the scarifier is preferred on the grounds of cost.

The scarifier is a cheaper implement than the disc or mouldboard plough (with more discs and mouldboards fitted for shallow cultivation).

It replaces the secondary cultivator.

If a special shallow disc plough or a shallow mouldboard plough is used the farmer will still need a scarifier for the next operation.

    A scarifier can be used for both primary and secondary cultivation. It may be necessary to change the points (see Cultivation and seeding ) but this will only take an hour to do.

The scarifier is well adapted to both the initial cultivation and the further cultivation.

It replaces a package of implements.

Why a scarifier?

 
I have called this tined implement a scarifier throughout this web site. It is important to distinguish it from the cultivator often found in the WANA region.

The cultivator has the correct tine spacing of 15 to 17 cm.

The cultivator is designed for secondary cultivation and the tines have a weak break away pressure. They cannot penetrate hard ground that has not been broken open by a chisel or plough.

The tines are not strong. The break away pressure can only be increased to a limited degree. If the break away pressure is increased too much the tines will bend.

The cultivator is usually mounted on two rows. Even with the small amount of trash in the WANA region these cultivators can block.

The scarifier in operation.

Diagram 3

    This shows the scarifier. An extra tine has been dropped into each gap between the tines of the chisel.

The tines are shorter.

The implement is worked at a shallow depth. Long tines are not needed. Shorter tines are stronger. T

he break away force on each tine is much greater than the cultivator but similar to the chisel.



 




        The tine spacing is most important.

                                                        Working width
                        Tine spacing     =   ------------------------

                                                          Number of tines.
 

Putting numbers on tine spacing

     * The chisel

     A normal tine spacing for a chisel is 30 cm or more.

If the chisel is fitted with 10 cm points for the primary cultivation the gap between the edges of the points is 20 cm.

Each point extends 5 cm from the centre of the tine. One on the left and one on the right leaving 20 cm between them.

It is obvious that if the chisel is set at 10 cm depth the strip between the tines with the 10 cm points is 20 cm wide and 10 cm deep.

Cultivating this through sideways action is very difficult. On most soil types impossible.

For the secondary cultivation 15 cm points are fitted. This will not make a great difference. The gap is still 15 cm.

At a depth of 10 cm this 15 X 10 cm gap is difficult to cultivate through sideways action.

If really wide points are fitted to close the gap between the tines completely a point of 30 cm is needed. It would be impossible to force such a wide point into the ground in most soil types.

    * The scarifier

    For a scarifier the tine spacing will usually be 15 to 20 cm.

If we use 15 cm as an example and fit 10 cm points for the first cultivation the gaps will be 5 cm between the two outside edges of the points.

It should be easy to cultivate a strip of soil 5 cm wide by 10 cm deep by means of sideways action.

Over time when the soil is level it will be possible to cultivate to a depth of 7 cm on most soil types.

For the secondary cultivation 15 cm points are fitted to the tine. The gap is now zero. All the soil passes under the points and weeds are completely cut off.
 
 

Putting the tines in rows
 

Diagram 4 and 5



Diagram 4 shows a scarifier where the tines have been arranged in three rows and Diagram 5 one where they have been arranged in two.

It is also possible to arrange them in four or more rows.

The tine spacing on both scarifiers is the same.

    Two row scarifier.

    The problem with the two row scarifier is working the soil and any surface trash through the implement.

The front rows open the soil. They also push the soil and trash to each side where it meets the tine in the next row. It is easy to block the implement even with relatively small amounts of trash.

The advantage of the 2 row is that it costs less.

The frame is smaller and uses less steel. 

It is also weighs less and the weight is closer to the tractor. This means that it can be carried on the linkage more easily.

Two row scarifier on a farm in Libya (El Marj). Note simple depth wheel.

One of the very few scarifiers in Tunisia. Two rows of tines and no depth wheel.

    Three row scarifier.

    Diagram 4 shows the three row scarifier.

The tine spacing is the same as the two row scarifier (that is working width divided by the number of tines) but because the tines in each row are further apart the implement can cultivate through more trash without getting blocked.

It will cost more than the two row scarifier.

The weight will be greater and further back which can be a difficulty for the linkage and balance of the tractor.

We recommend the three row scarifier for the WANA region.

Trash is usually well eaten by livestock during summer.

With the medic-cereal rotation any remaining cereal stubble rots down during the medic phase. The small amount of medic trash should cause no difficulties for a three row scarifier.

The most likely difficulty is the cultivation of cereal stubbles for vetch or grain legume crops.

Three row scarifier without depth wheel operated by the Jordan Cooperative Organisation.

    * Four and five row scarifier.

    This type of scarifier will not normally be needed in the WANA region.

These scarifiers have a greater ability to handle straw. They are common in Australia where there is a move towards conservation tillage practices which leave a straw mulch on the surface of the soil.

Farmers sowing vetch or grain legume every year into cereal stubble may find blockage problems in some seasons. Four or five row scarifiers are the solution.

The cost is substantially more.

The weight is so much greater and further back that four or five row machines are really only practicable as trailed implements.
 

Adding depth wheels and gauges.
  

    Depth wheels are another cost and another item to maintain.

Farmers are often reluctant to fit them or if they are fitted as original equipment they are sometimes removed.

Depth wheels are important with shallow cultivation to maintain an even depth.

With deep ploughing there is much greater tolerance. + 5  or - 5 cm will not make a significant difference at 20 cm and none at all if the depth is 25 cm.

With shallow cultivation a depth range of + 5 or - 5 cm around 10 cm depth is too great.

The linkage depth control on the tractor, even the most modern ones, cannot work to this level of accuracy.

    As well as the depth wheel we recommend a depth gauge that is independent of the wheels.

The wheels can have variable tyre pressure and sink further into soft ground. The position of the wheel is therefore not an accurate measure of depth.

An easy and cheap depth gauge can be made by hanging two pieces of chain from the back of the implement. One short chain indicates too deep. One long chain indicates too shallow.

Depth wheel with rubber tyre. These are spring tines with very narrow points.

    Long chain should bounce on ground.

    If it fails to bounce implement too high. Depth too shallow.

    Short chain should not bounce.

    If it bounces implement too low. Depth too deep.
 

The type of tine.
 

    Fixed tine.

    The fixed or solid tine is not recommended on most land in the WANA region.

There are some exceptions. Where there are no stones or obstacles of any type the fixed tine can be used. It is cheap.

If fixed tine cultivators are being used it should not be automatically assumed that a fixed tine scarifier will be suitable.

The fixed tine cultivator is used after a deep plough. The deep plough has dealt with the stones etc.

    Hinged tine with pin.

    Instead of a fixed tine, the tine can be hinged from a pivot.

The tine is held in place with a pin that shears when the tine hits a solid object.

The implement is lifted on the linkage. The tine swung back in place and a new pin fitted. It sounds a good idea in country where there are few obstacles.

It is cheap if not as cheap as the fixed tine and for small farmers the delay in resetting the tine would be compensated by the lower capital cost.

In more than thirty years of experience in the WANA region we have never seen one of these scarifiers so it remains a theoretical principal that is as yet untested.

    The spring tine.

    This is a fixed tine with a coil in the tine that allows it to spring out of the path of obstacles.

It is slightly cheaper than a spring release but not as effective.

There is no means of adjusting the break away pressure.

It is not recommended.

A two row scarifier with 13 spring tines. There is no depth wheel.

This shows the spring tine scarifier with steel depth wheels. While the tines can be adjusted on the bars (in this implement two bars) they cannot be too close of there will be blockages. A three row scarifier allows a closer tine spacing.

    The spring release tine.
 

Diagram 6.




    The above Diagram 6 shows the spring release tine.

It is hinged at the top with a robust pivot. Springs then hold the tine in position against the normal force of entering the soil.


    When the tine hits a stone or other solid obstacle it breaks away.

The tine lifts over the object and is returned by the force of the spring.

The tines are normally curved not straight as shown above.

The spring release is probably the most expensive of the above options but is greatly superior and is strongly recommended.

    Other mechanisms.

    There are other hydraulic release mechanisms which are claimed to be superior to the spring release. They are expensive. We doubt whether they are justified.
 

Break away pressure.
 

    The tine must be held in place with sufficient pressure to break open the ground.

If it hits a solid object the tine breaks away. The force required is the "break out" or "break away" pressure.

For the standard scarifier this will be about 150 to 200 kg. It is possible to increase the pressure by adjusting the pressure on the springs.

Only a limited amount of additional pressure can be applied. If excessive pressure is added to the springs the tine will not break away but will bend because the pressure is greater than the design.

    The higher break away pressure (and the stronger tine that goes with it) is the main difference between the scarifier and the cultivator.

Many farmers have a cultivator. This implement is used after deep ploughing to break clods and level the ground.

It has a tine spacing similar to the scarifier.

It has a much lower break away pressure. It will not cultivate new ground, only ground that has already been opened.
 

Points

     Points are fitted to the ends of the tines.

They work the soil. They wear and need to be replaced.

Points are made in different sizes. Small points penetrate better. Wide points cut off weeds better.

If the points fail to penetrate they may be worn or too large. Fit new points and/or smaller one. The worn points can be used for secondary cultivation or on row number 2 or 3.

The attachment of the point to the tine is a technical problem that has not been solved.

There are many systems. They all have their failings.

My preference is for a hoop over the point. The point has a tongue that fits under the hoop. The point is then bolted with a single bolt to keep it in place.

    Another common method is two bolts without a hoop.

    There are also "knock on" points. These have two points. One is attached normally. The other is a cover that slides over the first and takes all the wear. The slides converge.

As more pressure is applied the top point is more firmly attached or so the theory goes.

They are quick to change. A single blow with a hammer knocks them off. Another point is fitted and tightened with another blow of the hammer.

My experience is that they can also become detached when travelling on the road.

Points are also made from different types of steel or cast iron. Cheap point usually wear faster and expensive ones last longer.
 

Various types of points. Scarifiers are usually fitted with one of the points in the lower row.

Adding more width.

    The scarifier will normally be double the width of the deep plough it replaces.

This is a good rule of thumb to begin with. The scarifier will be used at a depth of 10 cm and the deep plough at a depth of 20 cm. or more. 

A farmer will begin by working the land to a depth of 15 cm for a few years to level the waves left by years of deep ploughing so a very larger implement would be difficult to pull.

When the ground is level a depth of 7 to 10 can be used. This will require less power.

    For the secondary cultivation the power requirement is also less. The implement can be worked at a higher speed or extended in width or a combination of the two.

    Working at a higher speed is practical but only to a limited extent. High speed working creates high ridges and deep furrows.

    Extending the width is a simple option particularly for small implements.

In the above diagram it is easy to bolt on wings with one extra tine each. The 9 tine is converted to an 11 tine implement.

The same can be done for larger implements but proportional the effect is less. That is an additional tine each side on a 15 tine implement only extend it to 17 tines.

    The additional width is most important. Shallow cultivation is about rapid preparation of seedbeds as well as lower cost.

If the addition tractor power release by shallow cultivation is not used in pulling a wider implement the advantages will be limited.

There will be a reduction in cost and more rapid preparation due to increased tractor speed but much less than the potential.
 

Trailed implements.
 

        If the standard three disc deep plough is replaced with a scarifier there are few difficulties.

For most medium sized tractors a 9 tine scarifier with three rows will be suitable.

It should be possible to carry this comfortably on the linkage with depth wheel.

The scarifier can be extended to 11 tines. If the weight is too great additional weights can be added to the front of the tractor or the front tyres can be filled with water. These are simple modifications.

    For larger tractors it will be necessary to change to trailed scarifiers. A scarifier bigger that about 13 tines becomes too cumbersome to be carried on the linkage of the tractor.

These are a couple of scarifiers. The one above is mounted on the linkage. The one below is a trailed implement. It is too heavy to mount on the linkage of a tractor.

Besides larger tractors will need double that number and more to fully utilise their power.

    The trailed scarifier is more expensive on a per unit of working width than the linkage scarifier.

    If trailed scarifiers or other trailed implements have not been used in the past it is necessary to modify the tractor with extra weight to reduce wheel slip.

See  Wheel slip  for details on how to ballast the tractor with the correct weight. More weight will reduce wheel slip but excessive weight will cause power loss. The correct balance needs to be achieved.
 

Pulling harrows.
 

    The basic principle of shallow cultivation is digging out the weeds and knocking them around to remove the soil from their roots.

The weeds then die of dehydration.

The harrows play an important part.

Fitting harrows directly behind the scarifier means that both operations can be carried out together. The clods are easier to break directly behind the scarifier before they have had a chance to dry. There is less moisture loss if the two operations are carried out together.

 

These are a pair of standard harrows. They come in various weights. Heavy harrows are needed behind the scarifier to make a serious impact on clods. Alternatively there are stump-jump harrows that are hinged horizontally. They are most effective and do not block with trash as much as the fixed harrows shown above.

Lighter harrows are used behind the seeder.

Tandem discs

Tandem discs are not recommended for shallow cultivation.

This is a tandem disc mounted on the linkage of the tractor.

This is a tandem disc (sometimes called a cover cropper) that is trailed.

The tandem disc has one great advantage It can handle trash. As I have mentioned trash is not a problem in the WANA region. Sheep eat the cereal stubble and there is very little residue left at the end of summer. With the medic - cereal rotation the cereal stubble (what little remains) breaks down during the pasture phase. The only trash is a little medic stubble.

Disadvantages of tandem disc

The tandem disc does not penetrate hard ground. It is not designed to do so. It is intended for secondary cultivation after deep ploughing. A scarifier can do both.

The tandem disc does not bury medic pods in the same way as deep ploughing but it mixes the top 10 cm of soil. Some medic pods are buried. The medic pasture will regenerate but is weakened.

The tandem disc does not level the ground in the same way as a scarifier.

Cost comparisons 

    There are hundreds of makes and models of implements so it is impossible to make precise cost comparisons but in general terms:-

    The scarifier will cost more than the deep plough or chisel it replaces. This is because it is double the width.

    The scarifier will cost about the same as the whole package of deep plough, cultivator and tandem disc.

    The trailed scarifier will cost about double the cost of a linkage scarifier per unit of working width.

    There are other complications regarding cost as all the scarifiers used in the WANA region have been imported from Australia.

These are more expensive than locally produced implements or those imported from nearby countries.

It can be seen from the above diagrams and the photos in the TRAINING KITS that there is nothing about the scarifier design that is complex or protected by patents.

They can be made locally at lower cost than importing from Australia.

As they are so simple the manufacturing can take place in stages.

When there is low volume of sales the tines can be imported and fitted to locally made frames. As the volume of sales increases more and more components can be made locally. Locally made implements have other advantages as they can be fitted with points that are already commonly available.
 
 

Scarifiers seeders   

    * Traditional seeders.

  

Seeding near Meknes in Morocco. The seeder has no cultivating or sowing tines. The seed is simply dropped on the ground and covered with a harrow. There is no fertiliser applied with the seed and certainly no placement. While the seeder is cheap it is not robust and does not last. The real cost of the seeder is the reduced yields from poor seed and fertiliser placement.

The traditional method of shallow cultivation was cultivation with a scarifier.

This was carried out twice.

The land was then sown with a seeder.

The seeder (not the one in the above photo which has no tines) had a row of cultivating tines.

Then it had two rows of sowing tines.

The tine spacing for these tines was 15 to 17 cm.

The fourth and final row of tines covered the seed and fertiliser behind row number 3.

Traditionally spring tines were fitted that cultivated the soil after the initial two cultivation by the scarifier.

This type of seeder is extremely efficient but needs to work in combination with the scarifier as the spring tines are not effective in penetrating hard soil.

On light textured soils it can be used alone.

In Libya farms were equipped with a scarifier and spring tine seeder of this type.  The weight of the seeder with seed and fertiliser is too great for the linkage.

These must be trailed machines. Their width is from 16 tines up to about 24 tines.

An all purpose machine - the scarifier-seeder.

    If the tines on the seeder are changed to spring release (with sufficient break away pressure) and an additional row of cultivating tines are fitted in front (5 or occasionally 6 rows in total) one has an all purpose machine that does everything.

The seeder is used as a scarifier with the seeding mechanism disengaged and then as a seeder.

A large number were purchased by the Algerian Government but unfortunately there was no follow up program of demonstration and they had no impact on shallow cultivation.

Seeder showing tine at front to open soil. Next row is for sowing. The tube from the seed and fertiliser boxes above feeds to a boot behind tine. The placement of seed and fertiliser together increases response to fertiliser.

This is the layout of the standard seeder. It has a front row of cultivating tines. It has two rows of sown and cultivating tines. There are 16 sowing tines in total. It then has a back row of covering tines. Behind these there are normally light harrow to level the ground and make harvesting easier.

    Direct drill.

    The scarifier-seeder can be used to sow seed directly into uncultivated ground.

The front two or three rows will scarify the ground.

The next two rows sow the seed and fertiliser and the final row cover the seed.

This is the perfect machine for sowing vetch and oats quickly after the first autumn rain.

It can be used for cereals provided herbicides are applied.

This is a heavy duty scarifier-seeder. There are three rows of cultivation tines. Then the sowing tines and finally the covering tines.

The standard seeder can be used effectively in the conventional package of scarifier two times and then seeder.

For the direct drill package the heavy duty scarifier-seeder is better.

    As a scarifier and then a seeder in a conventional package.

    The seeding and fertiliser mechanisms are disengaged and the scarifier-seeder is used as a conventional scarifier.

It can carry out the first cultivation, the second and then sow the seed and fertiliser.

    * Cost.

    The scarifier seeder will certainly cost more than the traditional seeder.

It will probably cost more than a linkage scarifier and traditional seeder but the difference will be small.

It will probably cost less than a fully trailed scarifier and trailed traditional seeder.

    * Advantages and disadvantages.

    The great advantage of the scarifier-seeder is its flexibility.

It can be used for a number of cultivating systems.

It is particularly useful for sowing vetch cheaply and quickly.

    The disadvantage for the small or medium farmer is the pace of change.

The linkage scarifier is a cheap implement that takes him down the road to shallow cultivation without great difficulty.

The scarifier can always be used as a cultivator if the farmer wishes to return to deep ploughing. The scarifier-seeder is cost effective only if it replaces all other implements. Farmers may not wish to make such a drastic decision. The scarifier-seeder is trailed. Farmers will need to ballast their tractor to make it work effectively.

Farmer Training kits show these implements in use. The Farmer Training Kit page will access the individual kits which consist of many photos and are therefore large files. I recommend you use a CD copy of this site to access the photos themselves.
 

Scarifier-seeder can work hard ground and seed at the same time. Note extra rows of cultivating tines.

Kit No. 1.5   Shallow cultivation.

Kit No. 2.3 Cultivation and seeding medic.

Kit No 4.1  Implements for shallow cultivation.

Kit No. 4.2 Using shallow cultivation to prepare a seed bed for cereals.

Kit No. 4.3  Sowing cereals.

Kit No 4.4 The dangers of deep ploughing with medic