THE CEREAL CROP

Deep ploughing and cultivation

Bad for profits


HomeFARMING ZONES IN WANAGuide to cereals and pastures >   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.

YOU ARE HERE

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.

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

DEFINITIONS

    Deep ploughing

        This refers to a depth of ploughing or cultivation greater than 20 cm.

The most commonly used implement is the disc plough. A three disc mounted version is frequently used in the WANA region.

A three mouldboard plough and chisel on a commercial farm at Le Kef, Tunisia. These are typical implements on farms in the WANA region.

Mouldboard ploughs are also used and less frequently the chisel or Canadiene. These implements are all designed to work at depths of 20 cm or more.

They are efficient at these depths.

Weed control is good although expensive. 

    Intermediate depth cultivation.

        Many farmers in the WANA region have found that deep ploughing or cultivating to a depth of 20 cm or more is too expensive.

They have reduced their cultivating depth to about 15 cm. This is a compromise depth.

Cultivating costs are reduced and the efficiency of cultivation is reduced but is still acceptable on most soil types.
 

    Shallow cultivation.

        Shallow cultivation is carried out at a depth of 7 to 10 cm.

The most commonly used implement is the scarifier.

This is described in detail in  Buyer's guide to scarifiers .

Disc and mouldboard ploughs for shallow cultivation do exist but they are expensive and not justified by any additional benefits.

The important point is that implements designed for deep ploughing or deep cultivation do not work well at a shallow depth. They can be adjusted to a shallow depth but fail to cut off weeds.

Shallow cultivation with the wrong implements is poor cultivation.
 

THE COST OF DEEP PLOUGHING

    Slow

    The diagram below shows deep ploughing compared to shallow cultivation.

It show how the same amount of energy expended on cultivation can be used to cultivate a small area to a depth of 20 cm or a large area to a depth of 7 cm. 

The slow rate of cultivation becomes an acute problem when the cereal-fallow rotation is changed. With the cereal-fallow the deep ploughing is carried out in the spring without an acute time constraint. (see  Rotations compared - competition for tractor time )

    When the rotation is changed to cereal-vetch, cereal-medic or cereal-grain legume all the ground is occupied by crops or pasture in the spring. All the ploughing is carried out in the autumn. Slow ploughing means late sowing. Late sowing reduces yields.

    Slow work can be overcome by increasing the power of the tractor or increasing the number of tractors. If this course of action is adopted crops can be sown on time but costs will increase.

    If shallow cultivation is used the rate of working is increased but the full improvement is only achieved if the implements are wider.

If the power used in deep ploughing in the diagram below is transferred directly to shallow cultivation the tractor could in theory be driven three times as fast.

There are theoretical and practical reason why this is impossible. To achieve a faster rate of working the ground a wider implement is required with similar tractor speeds.
 


 
 
 

    Cost

    The cost of deep ploughing is obvious. Whether deep ploughing is used in the cereal-fallow rotation or one of the replacement rotations it will cost more to work the land to a greater depth.

    There are other costs.

The cost of reduced yield (see above) can be offset by more tractor power but this in itself is an additional cost.

The capital costs are also higher.

Sometimes track-laying tractors are used for deep ploughing - although this is much less common as deep ploughing depths have been reduced from the ludicrous 30 to 40 cm used a few decades ago. The track laying tractors are a wasteful duplication as wheeled tractors are required for other tasks.

The implements used for deep ploughing (the disc plough, the mouldboard or the chisel) are used only for the first operation.

A range of other implements are needed to break down the seed bed to a good standard. The cost of these additional implements is greater than the extra width of the scarifier required for shallow cultivation.

This will be discussed in more detail but briefly a farmer using deep ploughing will have:

A deep plough + a cultivator of double or triple the width + harrows.

A farmer using shallow cultivation will have:

Only a scarifier and harrows which will cost more than the deep plough alone because it will be two or three times the width. It will cost about the same as the deep plough + cultivator package.

Alternatively the farmer may have a scarifier-seeder.

    Poor standard of seed bed preparation.

        Deep ploughing produces a rough seed bed.

Mouldboard plough in action. Notice large clods. Also most of surface material (in this case cereal stubble but could be medic pods) is buried.

There are large clods that must be worked many times in order to break them down into a reasonable tilth. The extra working adds cost to seed bed preparation.

It takes time. These are additional delays above the original slow working.

Delays to seeding reduce yields. If the seed bed is not well prepared germination is poor and the crop is uneven.

Deep ploughing also produces waves.

A wave caused by deep ploughing. Soil is thrown to one side and then to the other when the tractor returns.

This is an effect of the disc or mouldboard not the chisel.

These two implements move the soil in one direction. Over time the land becomes uneven. Commonly there are waves 15 or 20 cm deep and 10 to 20 m wide caused by the movement to the left or right as the plough works in one direction and then the other.

The effect of these waves is to make it difficult to apply herbicides evenly. The height of the boom is too close on the peak or too distant in the trough. If the waves are crossed the sprayer bounces and the application is poor.

The harvester has similar problems in coping with the waves. Harvesting efficiency is reduced.

Deep ploughing makes herbicide application uneconomic.

Herbicides can be a most effective means of weed control in cereals.

They can reduce the number of cultivations needed and thus reduce the damage to the soil structure. Crops can be sown earlier. All this assumes that a good seed bed can be prepared in one or two operations. Obviously with deep ploughing that is not the case. Many cultivations are needed to break down clods.

Herbicides become an additional cost not an alternative one.

Of course all these problems can be overcome with more effort.

More tractors can prepare a good seed bed rapidly but at greater cost.

More workings with a tined implement can level the waves but again at greater cost.

The reality on most farms is a combination of late work, poor seed beds and greater cost.

    Burying medic pods

    Shallow cultivation has become associated with the medic rotation.

If deep ploughing using discs or mouldboards is used in the autumn the medic pods left on the surface will be buried. They will be turned over with the soil and cannot germinate in future years from such a depth ( 20 cm).

Deep ploughing and fallowing are the major reasons for the destruction of the natural medic pastures that existed in the WANA region until the middle of the 20th century.

    While shallow cultivation is essential for the medic rotation in its traditional form deep ploughing can be used with the Zaghouan 4 rotation as the medic is re-established with pods.

The rotation does not rely on the regeneration of medic from pods left from a previous pasture phase.

Deep ploughing is not recommended. It is simply a convenient transition. With the Zaghouan 4 rotation shallow cultivation and medic are not linked. They can be introduced separately.

    The need for shallow cultivation in terms of saving time in the autumn is in fact greater for the cereal-vetch and cereal-grain legume rotations than for medic.

This fact is not yet widely recognised and is a major bottleneck in the introduction of these two rotations.

    More soil erosion.

    The link is simple. More cultivation destroys more soil organic matter.

With deep ploughing more soil is cultivated the first time.

After this more cultivation is required to break clods and level the ground.

All this futile activity destroys the structure of the soil. Poorly structured soil caps over easily with rain.

Water runs off.

Erosion increases.

 

Erosion gully forming. Deep ploughing and the cereal-fallow rotation are to blame.

THE ADVANTAGES OF DEEP PLOUGHING

    It would be impossible for deep ploughing with its additional costs to remain if there were no real or perceived advantages.

If the two systems were equal it would remain in force due to conservatism among advisers, machinery manufacturers and farmers.

In fact the advantages are strongly biased toward shallow cultivation and yet deep ploughing remains in force.

    Increased yields.

    In some experiments deep ploughing has shown a higher cereal yield.

Closer examination of these experiments shows that in every case all the implements used were those designed for deep ploughing.

These experiments do not show that deep ploughing is better than shallow cultivation. They show that implements designed to work efficiently at 20 cm do not work efficiently at 10 cm or less.

Where the correct implements have been used to compare deep ploughing and shallow cultivation equal yields have been produced.

In these experiments all other factors have been assumed as equal.

Of course all other factors are not equal on real farms. They are only equal at additional cost on research centres.

If these factors (delayed seeding and poor seed bed preparation) are taken into account deep ploughing produces a yield considerably lower than shallow cultivation. An experiment on these lines is too complex for current research methodology.

In the real world of farming the use of shallow cultivation has been a stunning success in the WANA region.

    In Libya in the early 1970s it was introduced to the Jebel al Akhdar region by Bashir Jodeh, the Director of the Jebel al Akhdar Development Authority. In the first year the Australia farmers and their scarifiers cultivated and sowed the cereal crops on a demonstration area.

The areas had been farmed in the past with the standard rotation used on most Libyan farms before the introduction of medic.

Local farmers protested to Bashir Jodeh. They claimed he was wasting project money by employing these people. "They only scratch the ground. The Australians are playing at farming" they said. "This is not real farming. Everyone knows that it is essential to plough deep." They continued.
    Bashir Jodeh asked for patience until the harvest. The spring rains were poor that year. The yield on the Australian demonstration area was a low 500 kg per ha. Due to the speed of cultivation the cereals had been sown two weeks earlier than the crops on local farms.

When it came to their harvest the local farmers had nothing. Bashir Jodeh called the protesting local farmers into his office and demanded, "Tell me now who is playing at farming?"

    The same good results were repeated again and again where countries (Libya. Iraq and Jordan) imported the complete medic package with its associated scarifiers.

In the other WANA countries with their fragmented packages, the farmers were left to adapted and modify existing equipment.

The project managers were not convinced that the Australian implements were really different.

They thought that the Australians were merely trying to sell their equipment as every other country (Europe, USA and Canada) had done before them.

The result was poor seed bed preparation and poor weed control.

Farmers became disillusioned with medic because of the poor cereal yield caused by poor cultivation.

    Water penetration

    Farmers and agricultural advisers (particularly on the northern shore of the Mediterranean but also in WANA) believe that deep ploughing opens the soil.

Heavy autumn rain enters the soil and it does not run off.

In fact the effect is extremely limited. The first rain does penetrate but soon the cracks fill either by the effect of the rain or the cultivation needed to prepare a seed bed.

Land with poor soil structure that has been deep ploughed. The cracks opened by the plough have all capped over with the first rain. Any further rain will produce considerable runoff.

Once this happens only better soil structure can save the land from soil erosion but the excessive cultivation has destroyed the soil structure.

    Any crop or pasture residues are also buried (like the medic pods) by deep ploughing. While they may not amount to much in the WANA region as they are so heavily grazed they can improve soil structure but only if they remain near the surface.

Buried down 20 cm they are useless.
 

More on deep ploughing in action see Training kit - The dangers of deep ploughing