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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

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

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

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.

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.





( Traditional rotation)




Cereal crop sown

Cereal crop sown

Cereal crop sown

Cereal crop sown


Cereal crop grows

Cereal crop grows

Cereal crop grows

Cereal crop grows


Cereal crop matures

Cereal crop matures

Cereal crop matures

Cereal crop matures


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


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.


Weeds grazed. Low stocking rate.

Medic pasture grazed. High stocking rate.

Grazed or more often left for hay.

Grain legumes grow.


Land cultivated for fallow

Medic grazed. Pods produced for future regeneration.

Cut for hay.

Grain legumes mature.


Bare soil vulnerable to erosion.

Pods and stubble grazed.

Stubble grazed.

Grain legumes harvested.

Stubble grazed.


Cereal cycle begins again.

Cereal cycle begins again

Cereal cycle begins again

Cereal cycle begins again


 Cereal - fallow rotation

    *  Cereal phase

        Yields of cereals after fallow are generally poor in the WANA region. 

Fallow can be effective in mobilising soil nitrogen from the break down of organic matter but the fallow rotation returns virtually no organic matter to the soil. Over a number of years there is less and less fertility in the soil and yield of cereals declines.

Long term rotational trials conduced by the Waite Institute of the University of Adelaide, South Australia, over the last 80 years demonstrate the declining fertility of the fallow rotation most clearly (see below).

Nitrogen fertiliser can be applied but the yield response is erratic in the WANA region due to the unreliability of the rainfall. In some seasons the application of nitrogen fertiliser can reduce yields. (see Making sense of fertilisers)

In the lower rainfall parts of the cereal zone (below 350 mm) the need for nitrogen is more acute yet the response from nitrogen fertiliser is more unreliable.

    * Fallow phase

    The return from the fallow is virtually zero.

The spontaneous germination of weeds in the autumn provides some grazing for livestock but the amount is small and the quality poor.

Stocking rates of less than half a sheep per hectare have been estimated for the fallow in autumn and winter. In the spring the land is cultivated and provides no grazing at all.

It is important to understand the devastating effect of fallowing in the spring and deep plough on all the potential pasture plants. Year after year the seed production is almost destroyed and any surviving seeds buried to a depth where they rarely germinate. This is useful for the following cereal crop but reduces the pasture output to an extremely low level.

    The low returns from the weedy pasture before the cultivated fallow mean that the total return from the rotation as a whole is a single cereal crop. In effect the land is required for two year to grow a single cereal crop.

Cereal - medic rotation

    * Cereal phase

    Yields from cereal crops are good provided weed control is good.

A good medic pasture will provide abundant nitrogen for the cereal crop which will be release gradually over the growing season.

There are no recorded examples (unlike nitrogen fertiliser) of yields being depressed by the higher level of soil fertility.

The classic cereal - medic rotation is a year of cereal followed by medic pasture which regenerates naturally from reserves of seed in the ground. There is no fallow.

* Medic phase

Returns from medic pasture can be excellent. The critical factor is the density of the pasture that regenerates in the autumn from the hard seeds in the pods.

With a good regeneration the pasture is productive early in the autumn/winter period. Production from livestock is good. There are savings in feed costs. Hat and grin is not needed. Instead sheep can be fed on cheaper cereal straw and green medic pasture.

The classic medic-cereal rotation has had problems in the WANA region because of a lack of scarifiers for shallow cultivation. The regeneration of the medic has been poor and the full potential in terms of increased returns has not been realised.

 Zaghouan 4 rotation.

 * Cereal phase

Fallowing after a medic pasture can provide the twin benefits of high levels of available nitrogen and excellent weeds control.

In most trials yields are even higher than with the classic medic - cereal rotation.

A figure of double the yield obtained using the traditional cereal-fallow rotation is a reasonable guide to cereal yield with the Zaghoun $ rotation.

The major problem is that fallowing prevents the medic from producing seed in the spring. There are few reserves of hard seed in the ground. The medic does not regenerate in the season after the cereal crop.

    If pods are harvested and broadcast on the cereal crop the pasture can be re-established at a low cost after the fallow/cereal phase.

If the pasture is retained for two or three years this low cost is spread over a longer period. This is the Zaghouan 4 rotation.

    As the fallow will destroy the medic pasture during the critical flowering period deep ploughing will not make any difference to the regeneration. Deep ploughing is of course more expensive and slower but in the short term the implements exist and can be used for the Zaghouan rotation.

    * Medic phase in classic medic - cereal rotation.

    Medic is best suited to grazing. Hay can be cut from medic but vetch is a better hay crop.

    A good grazed medic pasture will provide increased returns as follows:

    +  Reduced cost of hay and grain fed to livestock during winter.

    + Increased weight and price of lambs sold in the spring.

    + Reduced death rate of lambs fed on dry pods over the summer months.

    + Better lambing percentages of ewes in the following season due to high body weight at the time of mating.

    + In the long term greater numbers of sheep.

    The net value of the returns from medic listed above are discussed in more detail elsewhere.

Let us assume the farmer already has a flock of sheep and that the cost of the shepherd (family member or employee) is already included in the overhead cost of the farm.

All the increased returns listed above are profit after the annual cost of the medic has been accounted for.

If the number of sheep increases above 150 to 200 it may be necessary to employ another shepherd but for small and medium farmers the increased returns from medic pasture are very considerable indeed. In most cases they will be as great as the return from cereals.

Cereal - vetch rotation.

    * Cereal phase

    Yields can be good.

The vetch provides some nitrogen for the cereal crop.

Weed control in the following cereal crop is good if the vetch is cut for hay before the weeds have dropped their seed. The land is then grazed hard to prevent further weed seeds being produced

    * Vetch phase

    The vetch can be used for grazing. The returns are similar to those obtained for medic.

Medic and vetch have been compared in a number of trials conducted by ICARDA, ACSAD and other research institutions in the WANA region.

In general the experiments have found production level and the output of livestock from medic and vetch is similar.  Some trials have shown a slight advantage for vetch compared to medic.

Translating these results to farms is not easy as the medic will germinate with the first rain while the vetch has to be sown.

On the experimental stations, with plenty of machinery, the sowing of the vetch is carried out quickly after the first rains.

Most farmers will give priority to their cereal crops. Vetch will be sown later. Production will be lower. Vital winter production will suffer in particular.

The experiments comparing medic and vetch have also failed to take into account the value of medic pods left on the ground as summer feed and for future regeneration.

Vetch can be used for hay. In this case it is usually sown with oats. The quality of the hay is not good but the market for hay takes little account of quality and the returns can be excellent for farmers with machinery.

Farmers who are dependent on contractors for sowing, cutting and baling may find the net returns from grazing are better.

Cereal - grain legume rotation

    * Cereal phase

    Weed control is the major problem. The grain legume crop is harvested in late spring or early summer after the weeds have produced seed. These weed seeds are carried over to the cereal crop.

While vetch can be an effective "cleaning" crop grain legumes are the reverse and increase weed seeds.

    * Grain legume phase

    Returns are good provided weed control is good.

Cost per hectare is high so grain legumes are profitable where yield potential is high.

They should be grown on better land in better rainfall zones.

Long term cereal yields.

    One of the difficulties in comparing the common rotations in the WANA region is that yields need to be considered over a long period.

The cereal-fallow rotation for example will exhaust the soil but it may take some decades to do so. The grain legume rotation if used continuously may lead to a build up of weeds.

Table 1

    This show the mean yield of wheat in some long-term rotational trials carried out at the Waite Institute in Adelaide, South Australia.

Adelaide has a Mediterranean climate very similar to Tunis in Tunisia. 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.

The long term trials were begun in the era when wheat was king and no attempt was made to measure the pasture or livestock production.  


Mean yield of wheat in Kg per ha.

Period 1926 to 1951

Period 1952 to 1983

Continuous wheat
Wheat - grain legume (peas)
Wheat - legume pasture - legume pasture (3 years)
Not included
Wheat - legume pasture - legume pasture - legume pasture/fallow (4 years)
(Zaghouan 4 rotation except sub clover used instead of medic) 
Not included

There was no wheat-medic rotation included in these trials. They were conducted at the Waite Institute in the foothills of the Adelaide Hills. The acid soil is better suited to sub clover. Sub clover is difficult to manage in a classic two year rotation. It has lower levels of hard seed and the carry-over from one pasture phase to the next can be poor (there are now cultivars available with more hard seed). The researchers believed that a two-year rotation which required the reseeding of the pasture each second year was too expensive to be a practical. Of course the three year rotation could be practised with medic and there would be no need to reseed the medic as there would be an excellent carry over of hard seed.

* 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 when it has reached its exhaustion phase. (see below).

Table 2

Zaghouan 4 Rotation.

Traditional cereal - fallow

Three year rotation.

Two years legume pasture. One year legume pasture/ fallow. One year cereal.

During exhaustion phase from 1952 to 1983

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

Yield of wheat kg/ha




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 area

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

5 ha of sparse weeds for winter only.

6.66 ha of legume pasture for winter, spring and summer.

Pasture output.

This can only be estimated because the trials were conducted in an era when wheat was king and the main purpose of the pasture was to provide nitrogen.

5 ha @ 1400 grazing days per ha.= 7000 grazing days

2.5 ha @ 600 grazing days per ha = 1500 grazing days

Total = 8500 grazing days.

5 ha @ 250 grazing days per ha. = 1250 grazing days

6.66 ha @ 1400 grazing days per ha = 9324 grazing days


Cost of cereals low due to small area. Good yields due to good weed control and high soil fertility.
Good production of livestock.
Some opportunity cost from 2.5 ha of fallow.

Total output of cereals high but large area means that costs are 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 could be a problem on farms. The yield would fall.

    In strictly economic terms the three year rotation of sub clover pasture and wheat without a fallow is probably the most profitable rotation although it is not possible to say without knowing the cost of production for cereals and the returns from livestock.

Almost as much wheat is produced from one third of the land as the cereal-fallow. The area and cost of production is less and the farmer has two years of legume pasture as well.

Cereal production from the Zaghouan 4 is probably more profitable than the fallow rotation. 1000 kg more wheat is produced from the fallow rotation but costs are double as twice the area is sown.

The Zaghouan 4 is probably better than the three year rotation as farmers can use more of their established cultivation and weed control techniques. There is less risk.

More on Zaghouan rotations see  >>>>>  Zaghouan

    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. Of course 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.

Economic comparisons

    Economic comparisons are not easy to find nor are they easy to interpret.

They tend to be strict in their interpretation of costs. That means that family labour for shepherding is often included as a cost giving lower returns to livestock.

Our approach is that family labour is really a fixed or overhead cost. Farm families keep sheep already.

    ACSAD conducted an economic study of the medic rotation in relation to other rotations in Libya.

The study was conducted in the mid 1980s when medic had been established in Libya for more than a decade.

The study looked firstly at the returns from the rotation at current prices.

The ACSAD researchers also realised that the enormous subsidies paid by the Libyan Government for the production of wheat introduced a strong bias towards cereals production.

While subsidies for wheat production were common throughout the WANA region during the 1980s the Libyan level was much higher than other WANA countries.

Since then subsidies in the WANA region have decline so the "Without subsidy" figure is still relevant today as a comparison.

Table 3

Net Income (Libyan Dinar/ha)

At current prices for wheat.

Without subsidy on wheat

Jefara Plains (Western Libya)

Cereal - medic on project farms (Australian contractors)


-2.4 (loss)

Cereal - medic on private farms


-1.2 (loss)

Cereal - fallow on private farms


- 1.2 (loss)

Cereal - cereal on private farms



Jebel al Akhdar (Eastern Libya)

Cereal - cereal on private farms



Cereal - medic on private farms



    It can be seen from the above that the cereal - medic rotation produced the highest returns on private farms in both regions and with and without subsidies,

Gross Margins

    Gross margins are an old fashioned management tool that have stood the test of time because they are simple. There are many more sophisticated methods of calculating costs and returns using computers but gross margins can be calculated by farmers without computers or computing skills.

    Stage 1.

    Gross Margins are usually calculated on a per hectare basis although they can be on a per livestock unit or some other measure.

For a per hectare gross margin:-

    Expected return per hectare = (Expected yield) X (Expected price)

    Direct costs = the costs that can be attributed directly to the decision to grow that crop or pasture. The obvious ones are seed, fertiliser and herbicides. Also running cost for tractors. Additional labour is a direct cost.
    The cost of owning a tractor and the fixed labour force on the farm as well as all the costs of land ownership are considered overheads that must be paid for whether the crop is sown or not.

    Gross margin = Expected return - Direct costs.

    Stage 2.

    The Gross Margins are then placed in a list that ranks them in order with the highest Gross Margin at the top.

    Stage 3.

    The farming system is then planned using the list.

The objective is to devote as much land as possible to the first crop or pasture on the list. When the growing of this crop or pasture reaches the limits of the farm resources (suitable land, capital, machinery and labour) the farmer moves down to the next crop or pasture.

It may be necessary to move down more than one as the next crop may apply the same pressure on resources.

For example wheat may have a higher Gross Margin than barley but the resources needed for barley are similar to wheat. Once the limit for wheat production has been reached only a limited extra amount of barley can be grown. Using this system the farmer should obtain the highest possible Gross Margin for the farm as a whole. This is used to pay the Overhead Costs. Any surplus is the Farm Profit.

    Using Gross Margins

    Gross Margins can be quite effective in sorting out crops or pasture that have similar impact on the farm resources.

For example it is a useful exercise to calculate the Gross Margins for Vetch used as pasture, Vetch cut for hay, Lentils and Chick Peas as they have roughly similar resource requirements.

Even with these roughly similar crops there is an immediate problem. The crops have different impacts on the following cereal crop.

Vetches will reduce weeds and grain legumes will increase them. One possibility is to calculate a combined Gross Margin. That is the combined Gross Margin of the rotation - the cereal crop and the vetch or grain legume together.

    Using a combined Gross Margin has some value in comparing the four rotations in this study but a more comprehensive budget is needed if the farmer intends to change the whole farming system.

A change from cereal - fallow to cereal - medic can be done with the same or similar farm resources.

If the Zaghouan 4 rotation is used machinery resources can be reduced.

The change to vetch or grain legumes requires more tractor time. It is no longer possible to assume overheads remain fixed. Farmers may need extra resources and it is no longer feasible to include only the direct costs of fuel etc.

    Crops versus Pasture

    Gross margins are very sensitive to yields.

The Direct Costs are mostly related to the area sown whatever the yield.

If for example the direct costs are equivalent to the return from 500 kg of cereals per ha the Gross Margin is zero if the yield is 500 kg per ha.

If the yield is 750 kg per ha the Gross Margin is equivalent to 250 kg and if the yield increases to 1000 kg the Gross Margin doubles.

Low yielding crops on poor soil or in low rainfall areas are therefore unlikely to be profitable.

For livestock there is a completely different relationship. The Gross Margin per animal is not dependent on pasture productivity. A poor pasture stocked at a low stocking rate can return as good a Gross Margin per animal as a good pasture stocked at a high stocking rate. Of course there are pasture costs but with a regenerating legume pasture they are very low. The result is that land with a low productivity potential can be used more profitability for pasture.