ZAGHOUAN ROTATIONS

An old idea with a new twist


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THE ROTATIONS COMPARED

CHAPTER HEADING

SUMMARY OF CONTENTS

Soil erosion is the main sustainability issue for farming in the cereal zone of
the WANA region. The impact of the four rotations on soil erosion is
examined.

The possible benefits of moisture storage still lingers on as an issue with
many farmers. This chapter shows how moisture storage (if it occurs) cannot justify the use of a long cultivated fallow.

Costs and returns are the major determinants of farmers profits. The cost of production for each rotation is examined both for small and large farmers.

Returns relate to the level of output and price. This chapter looks mainly at
output.

For small farmers with few resources and financial reserves risk is
particularly import. A balance needs to be struck between high profits and
risk.

Each rotation has an inherent level of weed control. Other weed control
measures can be applied (see later chapters) but the natural ability of the
rotation to "clean" the land or otherwise is an important part of the decision
making process.

The amount of labour and the time it is used are an important aspect of each rotation.

This chapter looks at the capital requirements for each rotation but machinery is treated separately (see below)

Machinery is a special part of the general capital requirements. It is
particularly difficult for small farmers.

We have assumed that the starting point for most farmers is the growing of a cereal crop. We have examined the conflict between the requirement of the cereal crop and the new crop, new forage or pasture being introduced into the rotation.

Small farmers are resource poor. In this chapter we have selected the aspects of the above comparisons that would be appropriate for small farmers.

This chapter provide a framework for selecting a combination of the four
rotations and other variations.

YOU ARE HERE

The Zaghouan 4 rotation is not included in the comparison. It is an innovation from Tunisia that cleverly overcomes many of the problems of medic on small farms.

 
 

Zaghouan 4 Rotation

  What is it?

    The Zaghouan 4 rotation is completed in four years.

    This chart shows the rotation over a number of years. 


    Year Minus 1

    Medic pods are harvested from an old medic pasture on a neighbour's farm or government centre.
 

    Year 1  of the Zaghouan 4 rotation.

    Cereal crop is sown in the normal way. Medic pods harvested in the previous summer are broadcast over the crop.
 

      Year 2

    Medic pasture regenerates from pods in the soil.

These pods were broadcast over the previous cereal crop.

Hard seed in the pods broke down over summer and germinated with the first rain in autumn.

Pods can be harvested in the summer for broadcasting on another part of the farm.
 

    Year 3.

    Medic pasture regenerates from the pods produced in the previous year.

Pods can be harvested in summer for broadcasting on other fields or for sale to other farmers.

    Year 4.

    The medic pasture regenerates from the pods produced in the previous two years.

    In the spring the land is cultivated for a long summer fallow.

The medic is destroyed.

It does not produce pods or seed. There are pods in the soil from the previous year.

    Rotation now complete

    Year 5.

    The cereal crop is sown into the land that has been fallowed. This is the same as Year 1.

Medic will regenerate in the fallow but is destroyed by the cultivation, sowing and herbicides used for the cereal crop.

    Medic pods are broadcast over the cereal crop.

These will regenerate in the following year.

The rotation is completed in four years.

That is from the CEREAL crop in YEAR 1 to the FALLOW in YEAR 4.


    The concept of the Zaghouan 4 rotation has been researched in the Waite Institute long-term rotational trials for about 50 years.

The Waite Institute in South Australia has a similar climate to Tunis in Tunisia.

    The rotation has not been used on commercial farms in Australia because of the cost of reseeding the medic pasture after the fallow and cereals.

    During the 1990s ICARDA in Syria developed a medic pod harvester for small farmers and the techniques of establishing medic pasture using pods rather than seed. This is described in  Establishment using pods

    The harvesting and use of pods is a low cost means of medic establishment for small farmers and make the Zaghouan 4 rotation a feasible rotation for small farmers in the WANA region.


    Land use and Production
 

    This chart shows the rotation in action as it moves round a farm.


The land use is as follows:-

    2 full years of medic pasture. 50% of farm.

    1 year medic pasture in autumn and winter. Then fallow spring and summer. 25% of farm.

    1 year cereal. 25% of farm.

    If we compare the rotation with the fallow-cereal rotation it is obvious that livestock production is much higher as 75% of the land is in medic pasture during the critical autumn and winter period.

In spring 50% is still in medic pasture.

With the fallow rotation there are some poor weeds in the cereals stubble and these are then cultivated in the spring for the long summer fallow. There is cereal stubble but that is related to yield.

While the fallow cereal rotations has more land in cereals the yield is lower and the amount of stubble available for grazing is the same as the Zaghouan 4.

    The long term rotational experiments at the Waite (see below) have shown that the yield of cereals per ha. in the Zaghouan 4 rotation over nearly 50 years has been almost double the yield in the fallow-cereal rotation.

This means that the farmer produces the same amount of cereal from half the area.
 

    Output:

    Almost the same amount of cereal as fallow - cereal rotation.

    Sheep production many times higher than fallow - cereal rotation. Even higher than medic - cereal rotation.
 

Profit

    The profit from livestock is increased considerably compared to the fallow-cereal rotation.

It is also greater than the classic medic-cereal rotation as there is more pasture during the critical period of shortage in autumn and winter.

    The profit from cereals is increased when the Zaghouan 4 rotation is used as production costs (seed, cultivation, seeding, herbicides etc.) are mostly related to area.

Sowing half the area (compared to either fallow-cereal or medic-cereal) means half the direct cost.

Total returns from cereals are similar to the fallow-cereal rotation.

For small farmers dependent on contractors costs are particularly important. 

Output of cereals from the medic-cereal rotation can be greater in total than the Zaghouan 4 rotation but its success depends on the farmer's skill and ability to control weeds without a fallow.

If yields do not respond to the increase in soil fertility due to poor weed control farmers' profits from cereals will not be good.

As the farmer is also using unfamiliar scarifiers and implements for shallow cultivation there can be a failure of weed control.

Table 1

    This shows the mean yield of wheat in some long term rotational trials carried out at the Waite Institute in Adelaide, South Australia. The relevance of these trials to the WANA region is that Adelaide has a Mediterranean climate very similar to Tunis in Tunisia. This means it represents the better rainfall part of the cereal zone (500 mm). This may account for the length of time for some exploitative rotations to decline.
 
 

ROTATIONS

Mean yield of wheat Kg/Ha

Period 1926 to 1951

Period 1952 to 1983

Continuous wheat

874

692

Wheat-fallow

2300

1403

Wheat - grain legume (peas)

1668

1421

Wheat - legume pasture - legume pasture no fallow (3 years)

Not included

2033

Wheat - legume pasture - legume pasture - legume pasture/fallow (4 years)

The Zaghouan 4 rotation 

Not included

2402

Some important points

    The highest yield for cereals in the whole trial was achieved using the Zaghouan 4 rotation.

These results confirm our claim that a small farmer in the WANA region can produce almost as much wheat from a single cereal crop every 4 years as produced under the cereal-fallow rotation (see below).

Table 2

Output from three rotations.
 

Zaghouan 4 Rotation.
Two years legume pasture. One year fallow. One year cereal.

Traditional cereal - fallow during exhaustion phase. That is period 1952 to 1983 in Table 1.

Three year rotation.
Two years legume pasture. One year cereal. No fallow.

Yield of wheat kg/ha (see Table 1 above)

2402

1403

2033

Area of wheat on 10 ha farm

2.5 ha

5 ha

3.33 ha

Output of wheat on a 10 ha farm

6005 kg

7015 kg

6775 kg

Pasture output 

5 ha of legume pasture autumn, winter, spring and summer.
2.5 ha for autumn and winter only.

5 ha of sparse weeds for autumn and winter only.

 6.66 ha of legume pasture for whole year.

Comment

Cost of cereals low due to small area. High yield due to good weed control and high fertility.
Good production of livestock.
Some loss from 2.5 ha of fallow.

Output of cereals high but low yield means that costs high and profit possibly less than for other rotations. Virtually no livestock production.

High output of cereals and high output of pasture for livestock. Theoretically may be the best rotation in the trial but poor weed control and thus lower yields can be a problem on farms. 

    In strictly economic terms the three year rotation of pasture and wheat without a fallow is probably the most profitable rotation although it is not possible to say without knowing the relative prices for livestock and cereals.

Almost as much wheat is produced as the cereal-fallow.

The area and cost is less and the farmer has two years of medic pasture as well.

We believe that the Zaghouan 4 is both a better transitional rotation and carries less risk as farmers can use more of their established cultivation and weed control techniques.
 

The cost of producing the 6000 kg of wheat with the Zaghouan 4 rotation would be half of the cost using the cereal-fallow.

The livestock production from the Zaghouan 4 would yield a profit greater than the reduction in output from cereals.

    +  The next highest yield of cereal was obtained using the cereal-fallow rotation during the first 25 years. After that the fertility was exhausted and the yield collapsed.

The high yield was achieved during the first 25 years at a high cost as two years were required to grow a single cereal crop.

    + Grain legumes did not perform well.

In fact only marginally better than the cereal-fallow during the exhaustion phase and considerably worse (in terms of the cereal yield) during the first 25 years.


Advantages of Zaghouan rotation

     Profit

The profit is considerably greater than the cereal-fallow rotation.

It is similar to the medic-cereal rotation.

This increased profit is mainly from livestock.

Increased profit also comes from the reduced cost of production for cereals.

The Zaghouan 4 rotation does not require any investment. Existing machinery can be used initially and changed over time to shallow cultivation.

Risks are low.
 

    Fallow

    Fallow is an excellent means of controlling weeds and reducing cereal diseases.

It also mineralises organic nitrogen and mobilises it for use by the cereal crop.

The problem with the fallow-cereal rotation after a few years is there is almost no soil organic nitrogen to mobilise. This exhaustion of the fertility is faster in low rainfall zones.

In Table 1 above the fallow cereal rotation produced excellent yields for the first 25 years of the experiment.

It then collapsed and years over the next period were only 60% of those obtained while there was still reasonable residual fertility in the soil.

Compared to the classic medic-cereal rotation the fallow provides a much easier means of controlling weeds. It also makes more of the soil nitrogen available to the cereal crop in the early autumn and winter.

    Fallow also allows the farmer to split the cultivation work load between spring and autumn.

    Farmers are familiar with fallow. Farmers do not need to acquire as many new skills.

    The fallow used in the Zaghouan rotation is better than the traditional fallow.

With the traditional rotation there is a conflict between the needs of the livestock and the fallow.

Once the land is cultivated and the weeds killed the sheep must move to the parcour and roadsides until the cereal stubble are available for grazing.

Farmers fallow late or fail to control weeds on the fallow.

With the Zaghouan rotation there is no conflict. Half the farm is under medic pasture which is growing rapidly in spring.

Farmers can produce an excellent fallow. Cultivation can be done at the correct time and weeds properly controlled.

    Deep ploughing

    Deep ploughing is not recommended as it is costly and unnecessary.

If however farmers have deep ploughing implements they may not wish to invest in scarifiers immediately.

Deep ploughing can be used in the Zaghouan rotation.

Small farmers may be forced to use deep ploughing as they are dependent on contractors.

    Reduced tractor needs

    Changing from the fallow-cereal rotation creates greater pressure on tractor time in the autumn.

This is particularly acute with grain legumes and vetches. (See   Conflict with cereals  )

The Zaghouan 4 rotation actually reduces tractor time. There is the same split of tractor work between spring and autumn as the cereal - fallow rotation and only 25% of the land is cultivated instead of 50%.

Farmers may decide to adopt a Zaghouan 4 rotation on some land and cereal-grain legumes on other parts and keep their overall tractor time requirements the same.

We have stressed throughout this site that there is not single rotation that is suited to all farmers and all climatic zones.

A typical farm has different soils and slopes which can be used differently.

Hillsides are more difficult to cultivate and can be left for longer periods under medic.

Intensive systems of cereals and grain legumes are better suited to the flat land.

    Hay Production

    Hay production from medic pasture is described in detail ( Hay production) but essentially the problem is that cutting and removing the hay can remove the pods needed for future regeneration.

The simple solution to the problem is to make hay during a phase in the rotation when this removal of pods is not important.

    Year 1

    Medic regenerates from pods broadcast over cereal crop in previous year.
 

    Year 2

    Medic regenerates from pods produced in previous year.

The pasture can be cut for hay in the spring.

If pod production is lost the medic pasture will not fail.
 

    Year 3

    Failure of medic pasture to produce pods in Year 2 is not important. There is a carry over of pods and hard seed from Year 1.
 

Disadvantages of the Zaghouan 4 rotation

    Fallow

Fallow has its disadvantages as well as the advantages listed above.

It is unproductive.

The Zaghouan 4 rotation has only 25% of the land under fallow compared to 50% with the cereal-fallow rotation.

 The 25% in fallow is not completely unproductive as with the traditional cereal-fallow.

With the traditional fallow the autumn and winter period produces a pasture of sparse weeds.

With the Zaghouan 4 rotation the medic pasture germinates in the autumn to produce a productive pasture. The medic grows on through winter and is cultivated in early spring.

Perhaps 60 or 70% of the total annual pasture output is lost through the spring fallow but the early autumn and winter pasture is more valuable to the farmer.

The economic loss is less - perhaps only half.

Whereas the fallow year in the fallow-cereal rotation produces virtually nothing the fallow year in the Zaghouan 4 rotation produces some months of excellent pasture.

In total the opportunity cost of lost production of the fallow is equivalent to the production from 12.5% of the land. This is not high if cereal yields are double.

Fallow also leaves the land vulnerable to erosion by wind and water.

The Zaghouan 4 rotation has only 25% not 50% in fallow.

The quality of the soil structure is much better. After 2.5 year of medic pasture and the return of organic matter the structure is good. The rain will be absorbed and not run off.

    Inflexible.....

    Like all fallow rotations the Zaghouan 4 is inflexible.

The land is cultivated in the spring for the fallow.

If the following autumn rains are poor the farmer is already committed to a cereal crop in the sense that part of the cultivation has already been done and the cost incurred.
 

    ......  but not as inflexible as the traditional cereal -fallow rotation.

    The farmer is not as committed as with the cereal-fallow.

If shallow cultivation was used for the fallow in the spring there will be medic pods in the surface of the soil from the previous year.

Some seeds will germinate and form a medic pasture.

Normally this will be cultivated and the cereal crop sown.

If the autumn rain is poor the farmer may decide to leave this medic in place rather than cultivating and sowing a cereal crop.

The time and effort spent on the fallow in the previous spring will have been wasted but if the rain is poor this may be better than wasting even more money on further cultivation, cereal seed and fertiliser.

 The medic phase also provides flexibility.

If the season is better than average the farmer can cut surplus pasture growth and make hay for sale or as a drought reserve.
 

How to use the Zaghouan 4 rotation?
 

As an introduction to medic.

    One of the difficulties with the classic medic-cereal rotation as used in Australian and some WANA countries is that it can lead to a skills and management overload.

    The farmer must acquire new skills:-

          +  to establish medic using seed

          +  to graze green medic

          +  to manage the dry pods over summer

          +  to understand shallow cultivation for cereals

         +   to control weeds and sow cereals without fallow.

    The Zaghouan 4 rotation allows all the extension and training effort to go into the medic. The cereals can be grown as before - even using deep ploughs.

    Farmers may decide after some years to change to a classic medic-cereal rotation.

As a permanent rotation

    For small farmers livestock grazed on good medic pasture are likely to be more profitable than cereals sown and harvested by contractors.

The Zaghouan 4 rotation may be more profitable than medic-cereal as there is more medic pasture.

Small farmers may also find it difficult to change to shallow cultivation as they are in the hands of contractors who do not have scarifiers.

    The Zaghouan 4 rotation has the additional cost of:

    + establishing the medic from pods every fourth year.

    + the loss of spring pasture by fallowing in one year out of four.
 

These costs are offset by a high yield of cereals after fallow provide there is good medic pasture to fallow.

A lower herbicide use than the classic medic-cereal rotation.

Farmers will need to make a detailed cost comparison.

As a restorative rotation.

    If a farmer adopts the classic medic-cereal rotation there is a danger that the medic pasture will be over run with weeds.

This may be due to natural climatic factors or poor management.

The pasture can be restored through good grazing management but a quicker solution may be to break the cycle of weeds with a fallow and reseed the medic using pods and start again.
 

How to increase cereal production?
 

Zaghouan 3

    This is an alternative version of the Zaghouan 4 rotation that is completed over three years by eliminating a year of medic pasture.

The cost of pod harvesting and broadcasting is probably too high when the return is only one full year of medic and one half year.

Again individual farmers need to budget the two rotations.

I doubt whether the rotation is economically sound.
 

Zaghouan 5

    The Zaghouan 5 is a little experimental. Unlike the Zaghouan 4 which has 50 years of research behind it the Zaghouan 5 requires some further trials.


 The starting point is really good medic pasture.

If the medic is dominant with weeds and grasses at a low level the medic will produce ample nitrogen for more than one cereal crop.

The rotation is as follows:-

Year 1

Medic germinates from pods broadcast over cereal crop. Good management. Medic dominant.

Year 2.

Medic pasture germinates from previous year's pods. Good management. Medic dominant.

Year 3

Medic germinates from previous two years' production of pods. Fallow in spring.

Year 4

Cereal crop sown on fallow.

So far Zaghouan 4 rotation.

Pods not broadcast over cereal crop at this stage.

Year 5

Second cereal crop sown into cereal stubble.

Medic pods broadcast. 

Cereal yield will be lower than the previous year but if original medic pasture was good and if weeds are controlled yields should be good.

The advantage of this rotation is that more cereals are produced. Medium and large farmers may favour this rotation.

An alternative is to sow a grain legume crop in Year 5.

The reasoning behind this is that the fallow carried out in Year 3 controlled weeds to a high level.

The cereal crop grown in Year 4 was vigourous and was sprayed with herbicides.

The level of weed control remained good.

Grain legumes could be grown in the cereal stubble and the medic pods broadcast over the grain legume.

Table 3

Wheat yields of two successive crops grown after various lengths of Sub Clover based pasture at Kojonup in Western Australia. I have not been able to find research conducted with medic but Sub Clover is a similar annual legume that is adapted to more acid soils than medic.

Period of Sub clover pasture before wheat crops

Yield of wheat kg/ha

Second wheat crop as % of first

First crop after clover

Second crop after clover

No Sub Clover pasture

1,057

884

83%

1 year clover

1,824

902

49%

2 years clover

1,623

1,126

69%

3 years clover

1,938

1,319

68%

4 years clover

2.034

1,286

63%

5 years clover

2,260

1.751

77%

It is possible to predict from the above results that the second wheat crop will be about 60% to 70% of the first crop.

Land use

    Medic pasture - 40%

    Medic pasture in winter and fallow in spring - 20%

    Cereal grown on fallow 20%

    Cereal or grain legume grown as second crop 20%
 

Zaghouan 5 - as Zaghouan 4 + 1
 

The Zagouan 4 + 1 is different from the Zaghouan 5 because the rotation was planned as a Zaghouan 4 but a extra cereal crop was grown. That is the medic pods were broadcast over the cereal grow grown on the fallow.

In the next season the medic pasture generated from the seed in the pods.

The farmer decided because of exceptionally good rains that he would grow another cereal crop.

The medic pasture was cultivated and sown to cereals.

In the following year the medic should regenerate from further reserves of hard seed in the pods.

More flexible

One of the greatest weaknesses of the present farming system in the WANA region based on fallow-cereal is its total inflexibility.

Cereals must be sown or nothing grows except a few poor weeds with little feed value.

More cereal crops cannot be grown as many trials have shown that cereal after cereal produces very low yields.

    A more flexible approach to cereals in the cereal zone of the WANA region is important for improved profitability. This is particularly true in the lower rainfall part of the cereal zone.

The aim should be to grow less cereals in dry years and more in wet years.

The aim of this rotation is to prepare for a Zaghouan 4 but add on a extra cereal crop if the season is good.

Further experiments would be needed to see if medic pods broadcast in Year 4 would survive to regenerate in Year 6.

In theory there should be sufficient hard seed for good regeneration but this needs to be demonstrated in the field.
 

    An examination of the fate of hard seed.

 Under the classic medic-cereal rotation.

    Season 1

    Pods produced and drop on ground. Summer grazing of pods well managed.

    Season  2

    Pasture regenerates from seed in pods. Depending on variety and climate perhaps 30 to 40% germinate. These are destroyed when the land is cultivated. Cereal crop sown.

    In summer pods remain near surface. More hard seed breaks down.

    Season 3

    With the autumn rain the medic seed germinates and the pasture regenerates.

Pasture is then left as a new pasture equivalent to Season 1.

Perhaps 40 to 50% of the original seed will germinate. With the previous germination in Season 2.  80% or 90% of the seed produced in Season 1 has now  germinated.

    Season 3  + second cereal crop

    If another cereal crop is sown instead (as we are suggesting in the Zaghouan 4 + 1 rotation) this germination of medic is destroyed.

    Season 4

    The germination of the medic is now likely to be extremely weak.

Only 20 to 10% of the seed remains.

It may not be viable.

It may be to deep to germinate.

It may have been eaten by ants.

A second cereal crop in Season 3 is not recommended for this reason.
 

Under a Zaghouan 4 + 1 rotation.
 

Season 1

    Medic pasture from pods broadcast over previous cereal crop.

Season 2

    Medic pasture from pods produced in previous year.

Season 3

    Medic pasture from pods produced in previous two seasons.

Fallow means no pods are produced.

Season 4

    Cereals are sown.

Pods are broadcast.

The pods were harvested from another area of medic pasture in the previous spring.

The medic pods were stored in sacks.

The breakdown of seed hardness should be low.

Only a small percentage should germinate in the cereal crop.

Season 5  for Zaghouan 4

    The pods broadcast in Season 4  have now remained on the surface of the soil during the summer.

Hard seed has broken down.

Perhaps 40 to 50% of the seed will germinate and form a good medic pasture.

The Zaghouan 4 rotation is complete.
 

Season 5 for Zaghouan 4 + 1

    If the farmer now decides that the rains are exceptionally good and there is an opportunity to sow an extra cereal crop to take advantage of the favourable season this medic pasture will be destroyed.

This is now a Zaghouan 4 + 1 rotation.

Season 6

    In theory there should still be enough medic seed in the pods to form a good pasture.

The reason is the the medic pods have spent one summer in sacks and two summers on the ground. If the farmer tries to have an extra cereal crop with the classic medic-cereal rotation the medic pods will have spent three summers in the full heat.

That is the theory.

It needs practical confirmation.