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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.

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

Making a choice between the four rotations 

Small resource poor farmers

                  In  "Suitability for small farmers"  we demonstrated that a modified medic rotation (Zaghouan 4) will be the basic choice for resource poor farmers.

    The Zaghouan 4  rotation offers very considerable advantages for small farmers without tractors or machinery.

Livestock production is increased because there are 2.5 years of medic pasture.

The cereal area is reduced from 50% of the land to 25% but as the yield is almost double the output of cereals remains the same.

The cost of production is reduced by half so the profit from the small area is much greater and the risk less.

  In this section we look at the choices facing medium and larger farmers with their own machinery and access to greater amounts of capital.

More evenly balanced

The returns from the three rotations that have been designed to replace the cereal-fallow are more evenly balance on larger farms. These farmers have their own machinery and employ shepherds for their livestock rather than family labour.

Shallow cultivation needed

    Whatever the rotation adopted as a replacement to the cereal-fallow farmers will need to use shallow cultivation in order to reduce their costs and increase the speed of preparing a seed bed and sowing. Without shallow cultivation the additional investment in farm machinery and tractors will reduce the profitability of the vetch and grain legume rotations in on large farms with their own tractors.

A place for all three rotations

    Farmers will select a farming system based on a mixture of all three replacement rotations. This may sound complex but it follows some simple guidelines.

   *  Grain legumes.

    These can produce high returns but have high costs and a high risk.

They increase weed seeds in the soil and the potential weed contamination of the following cereal crop.

Erosion potential is high.

Farmers will use some of their best level land for grain legumes. This is less vulnerable to erosion. Yields will be higher and the margin over costs greater.

They will use a rotation that alternates grain legumes with cereals but also with vetch to clean up weeds.

For example they may use the following:

Cereal - grain legume - cereal - vetch. 

Grain legumes can be grown with less risk in the higher rainfall parts of the zone rather than the lower rainfall areas.

    * Vetch for hay

    Vetch for hay fits in well with grain legumes as it provides a good opportunity to reduce the reserves of weed seeds in the soil.

However it is a crop with considerable erosion potential so it is better grown on land that is reasonably level rather than a slope.

Costs and risks are lower than grain legumes so profitable vetch crops can be grown in areas with lower rainfall.

    * Medic pasture

    Medic pasture provides a base for all farmers in all zones.

    Medic pasture will be grown on poorer soils and steeper slopes. This applies to all parts of the cereal zone. In many cases this land will be more profitably used for permanent medic pasture or a long rotation of 2 or 3 seasons of medic for each cereal crop.

    Medic will be grown in lower rainfall areas. Although farmers have the machinery or can purchase more for the grain legume and vetch rotations they may find the medic option in low rainfall areas is more profitable and carries considerably less risk.

Economic comparisons.

    * Gross Margins.

    We have already mentioned gross margins as a useful tool to compare the various rotations.

Gross Margins per ha = Total Returns per ha - Direct Costs.

    When Gross Margins are used as a means of selecting the most profitable rotation the farmer selects the crop with the highest Gross Margin to grow to the maximum possible extent.

The maximum area may be the area of suitable soil or slope on the farm.

It may be limited by the machinery available, by the labour or some other factor.

Crops are then selected with lower Gross Margins but outside these resource limits.

For example if labour at harvest is a limiting factor for the production of grain legumes the farmer can then move to vetch or medic as these have different labour requirements.

    The constraint of machinery time in the autumn produces particular problems and farmer may need to balance their grain legumes which require a substantial increase in machinery time with the Zaghouan 4 rotation where a considerable reduction of machinery is possible.

    * Combined Gross margins

       The difficulty with the simple Gross Margin approach outlined above is that the crops have an impact on the subsequent cereal crop. It is therefore more realistic to use a combined Gross Margin for the legume and the following cereals crop.

Thus a grain legume crop may have a high individual Gross Margin but this may have to be offset against the next cereal crop if it a low Gross Margin due to weed infestation or high weed control costs.

The reverse applies to vetch. The Gross Margin may be lower but by controlling weed seeds the next cereal crop will have a higher yield and higher Gross Margin.

    The Zaghouan 4 rotation will need to combine the whole four years as an average Gross Margin if it is going to be compared on the same basis as the other two-year rotations.

    * Yield potential

    A further difficulty with the use of Gross Margins as a management tool is that it is very sensitive to yield variations.

Let us say for example that a cereal crops on a farm yields 1000 kg per ha. on average.

Let us also say that the Direct Costs amount to the equivalent of 700 kg/ha.

The Gross Margin is therefore equivalent to 300 kg/ha.

It is not possible to predict the yield of the cereals in a single season but it is possible to predict from individual field records the Yield Potential. Based on these figures it is possible to calculate that certain fields have a lower potential than other. This is nothing startling. Farmer know that certain fields are better than others even if they have not measured the differences.

    Unless these difference are taken into account the Gross Margin has little meaning.  On an individual farm a variation in yield between 700 kg/ha and 1300 kg/ha is possible. While some of this variation may be due to management factors such as time of sowing they also reflect the inherent fertility of the soil.

In fact the two can be linked. We advocate the use of a priority management system where management decisions are always made in favour of the best land as the results will be expressed in the greatest yield response.

 Returning to our example it can be seen that the variation in yield means that the Gross Margin for cereals can vary  from zero (where the costs are equivalent to 700 kg/ha and the yield is 700 kg/ha) to double (costs are still 700 kg/ha but yield are now 1300 kg/ha rather than the 1000 kg/ha average for the whole farm).

    Obviously there is no point in sowing cereals with a Gross Margin of zero and medic will produce a higher return. Under the cereal-fallow rotation the farmer had no choice as the fallow produced nothing and even a tiny Gross Margin was better than nothing.

Field A

Field B

Field C

Cost of production = the return from 700 kg of cereals

Cost of production = the return from 700 kg of cereals

Cost of production = the return from 700 kg of cereals

Yield = 700 kg

Yield = 1000 kg (average for whole farm)

Yield = 1300 kg

Gross Margin = 0

Gross Margin = 300 kg

Gross Margin = 600 kg

The above table shows the Gross margins for each field. It is a slight simplification. There are some production costs that are related to yield such as the transport of the grain but the great majority of costs are related to the area of land and do not vary with the yield.

    * Gross margins for pasture and livestock

While the Gross Margin for sown cereal crops, vetch hay and grain legumes are very sensitive to yield fluctuations that is not true of pasture.

The cost of medic pasture once it has been established is very low. It is only an annual application of phosphate.

Medic pasture only has a Gross Margin when it is converted into livestock products. It is therefore necessary to calculate the Gross Margin for sheep.

The Gross Margin is related to the ability of the farmer to obtain high lambing percentages, high growth rates and low death rate from the flock. These are not dependent on pasture yield. Land with low productive potential can be used for pasture more profitably than for crops. The Gross Margin per sheep on this low quality land will be the same. There will be fewer sheep per hectare but the returns should still cover the fertiliser cost comfortably and make a profit for the farmer whereas a low yielding cereal crop can make a loss.

Field A

Field B

Field C

Output of medic pasture = 2000 kg of Dry Matter

Output of medic pasture = 3000 kg of Dry Matter

Output of medic pasture = 4000 kg of Dry Matter

Production cost = 100 kg of P fertiliser

Production cost = 150 kg of P fertiliser

Production cost = 200 kg of P fertiliser

Stocking rate = 2 sheep

Stocking rate = 3 sheep

Stocking rate = 4 sheep

Gross Margin = Gross Margin on 2 sheep less 100 kg of fertiliser.

Gross Margin = Gross Margin on 3 sheep less 150 kg of fertiliser.

Gross Margin = Gross Margin on 4 sheep less 200 kg of fertiliser.

The above table shows that medic pasture once it has been established has very low variable costs. The Gross Margin per sheep show remain on each field provide the stocking rate is adjusted to the amount of pasture produced. Even the poor Field A will produce a return.

    * Overheads.

    The other failing of the Gross Margin approach is that it implies small changes in the amount of crop sown rather than the complete elimination of the fallow as the above rotations imply.

The overheads do not change when marginal changes are made between crops and pasture. If the whole area of the farm is converted to grain legumes or vetch in rotation with cereals obviously overhead will change considerably. Much more machinery time is needed.

Farmers will need to carry out a more comprehensive budget.

The Gross Margins can still play a part. The total Gross Margin for the farm is calculate before the rotations are changed. The total Gross Margin is calculated after the rotations have changed. The two can then be compared.

The difference is not all profit. The increase in overhead costs must be taken into account first.

Individual farms.

    One of the characteristics of the last 50 years of development in the WANA region has been a tendency among scientists and extension advisers to apply a "one size fits all"  solution to the optimum rotation for the cereals zone. Based on experimental results from small trial plots there has been a tendency to advocate grain legumes as "the solution" or vetch as "the solution."

We have already demonstrated that there is no single solution. That all the rotation have a place. That economic returns need to be moderated by other management factors.

Besides the obvious factors such as access to machinery and capital individual farmers have different skills and desires which must be taken into account. Some farmers will have greater skills with animals and will be able to obtain higher lambing percentage and growth rates than other. It is only sensible for them to give more emphasis to their animal enterprise. Others love tractors and should expand the cropping and perhaps become contractors or share farmers. They can reduce their animal enterprise, produce more hay for sale and rent out much of their grazing.

    An example:

    Let us say that a farmer has 15 ha of land.

    5 ha are flat on the plain.

    5 ha are moderate slope and moderate soil depth.

    5 ha are steep and stony.

    Currently the fallow-cereal rotation is used.

    The plain has a yield potential of 1500 kg/ha

    The moderate slope 1000 kg/ha

    The steep slope 500 kg/ha.

   1. The farmer may use the cereal-grain legume rotation on the plain. This will require considerably more machinery time - perhaps 4 times as all the crops need to be sown in the autumn.

   2 On the moderate slope he may adopt a Zaghouan 4 rotation. The yield of cereals will be 2000 kg/ha compared to the existing 1000 kg/ha using the cereal-fallow rotation and the area of cereal will be half. Machinery needs will be less.

   3  On the steep slope the farmer may grow permanent medic as the production of cereals with a yield of 500 kg/ha is not profitable. Even a Zaghouan 4 rotation and a yield of 1000 kg/ha may not be attractive. This will also release tractor time. Overall the increase in machinery for the cereal-grain legume may balance the reduction for the Zaghouan 4 and the permanent medic.

Here is the above diagram in action in Algeria.