ROTATIONS COMPARED

CONFLICT WITH CEREALS FOR TIME AND OTHER RESOURCES. 

Home > FARMING ZONES IN WANAFarmers' guide to cereals and pasture  > You Are Here

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.

YOU ARE HERE

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.

FOUR COMMON ROTATION ON THE GROUND IN THE WANA REGION

SEASON

ROTATIONS

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.

Grain legumes harvested.

Stubble grazed.

AUTUMN

Cereal cycle begins again.

Cereal cycle begins again

Cereal cycle begins again

Cereal cycle begins again


 

What is the conflict between cereals and the other parts of the rotation?


     An example using current farming methods:

    A farm of 100 ha with tractor and other cultivating and seeding equipment.

The same principles apply to smaller farms. We have simply used 100 ha to avoid decimal points.

    * Cultivating techniques remain unchanged. That is depth of cultivation

    * Management unchanged. That is no additional herbicides as an alternative to cultivation.


Cereal - fallow rotation.
 

* Cereals

Autumn:   50 ha. cultivated and sown to cereals. Let us say work done in 3 weeks allowing for weather delays and breakdowns.
 

Spring:      50 ha cultivated for fallow. The ground is hard. Cultivation carried out to a depth of 20 cm. It is slower than secondary cultivation and seeding (as above). Let us say 3 weeks although there are few pressures on time.
 

Cereal - medic rotation
 

* Cereals.

Autumn:  50 ha. cultivated at least twice and sown to cereals. 3 weeks for first cultivation assuming the same method as above (that is deep ploughing). 3 weeks for secondary cultivation and seeding.

            Total   =  6 weeks.  Cereal yield may be reduced due to late sowing.
 

* Medic

Autumn:    No tractor capacity needed once regeneration phase is reached.
 

Spring: No land preparation as all land is occupied by cereal or medic.
 
 

Cereal - vetch rotation.
 

* Cereals.

Autumn:  50 ha cereals - as above in cereal-medic rotation = 6 weeks instead of 3 assuming tractor the same depth of cultivation of 20 cm.

* Vetch

Autumn:  50 ha vetch - land preparation to a lower standard than the cereal crop. Let us say 5 weeks.

    Total = 11 weeks. If cereals received total priority yield may be reduced slightly but vetch yield will be substantially lower.  

Spring:  No land preparation. All land is in vetch or cereal crop.
 

Cereal - grain legume rotation

* Cereals

Autumn:  50 ha. cereals - as above in vetch or medic rotation. = 6 weeks of work

* Grain legume

Autumn: 50 ha. grain legumes. Land needs to be prepared at least as well as cereals preferably better. Let us say 6 weeks.

    Total = 12 weeks. Late sowing will be serious problem for low priority crops.

Spring: All land occupied by cereal or grain legume.
 

Zaghouan 4 Rotation.

Similar to cereal-fallow rotation above but only HALF as much tractor time because only one quarter of land sown to cereals. Medic does not require cultivation.
 

Table 1.

    The rotations compared.
 
 

SEASON

ROTATIONS - ON 100 HA. EXAMPLE FARM

ZAGHOUAN 4

CEREAL - FALLOW

CEREAL -MEDIC 

CEREAL - VETCH

CEREAL - GRAIN LEGUME

SPRING 

25 ha. cultivated. 1.5 weeks work.

50 ha cultivated. 3 weeks work.

All land occupied by cereals or medic pasture. No cultivation possible.

All land occupied by cereals or vetch. No cultivation possible.

All land occupied by cereals or grain legumes. No cultivation possible.

AUTUMN

25 ha cultivated and sown to cereals. 1.5 weeks work.

50 ha cultivated and sown to cereals. 3 weeks work.

50 ha cultivated X 2 and sown to cereals 6 weeks work.

50 ha cultivated X 2 and sown to cereals. 6 weeks work.
50 ha cultivated and sown to vetch. Perhaps 5 weeks work.

50 ha cultivated X 2 and sown to cereals. 6 weeks work.
50 ha cultivated X 2 and sown to grain legumes. 6 weeks work.

AUTUMN Tractor Time needed using deep ploughing.

1.5 weeks.

3 weeks

6 weeks

11 weeks

12 weeks

AUTUMN Using shallow cultivation instead of deep ploughing.

5 days.

1.5 weeks

3 weeks

5.5 weeks

6 weeks.


 

Purchasing more farm machinery and tractors.

    The 11 to 12 week delay in seeding for the vetch and grain legume rotations in the above example is exaggerated.

If crops were sown that late they would produce no yield at all.

The farmer is sowing double the area of crop (vetch or grain legume) compared to the cereal-fallow rotation. He must expect to have more tractor power and machinery.

It can be argued that the extra power will cost less than double because large machinery usually costs less on a per metre or per horse power basis. The returns from the new crops should provide a good return on the additional investment.

Even with double the machinery capacity seeding is delayed. The fact that all the ground is now occupied during the spring means that all the cultivation and seeding has to be carried out in autumn.

If the farmer wants to sow the crop at a similar time to the previous cereal-fallow rotation more power will be need again. This is a serious problem that can undermine the profitability of the new rotations.

In the above example seeding took place 6 weeks after the opening rains instead of 3 weeks. This is a hypothetical figure. On actual farms it may be more or less and its significance in terms of reduced yield will vary. It is important to recognise the problem otherwise the theoretic results achieved on research centres will not be translated onto farms. Yields will be reduced or costs will be increased if the work is carried out in a shorter period using more machinery.

Shallow  cultivation

        Shallow cultivation provides a solution to the mechanisation and timing problem. Shallow cultivation has usually been associated with the cereal-medic rotation. Shallow cultivation is essential for medic as deep ploughing buries the medic pods and they do not regenerate in future years.

It can be seen from the above example shallow cultivation is essential for economic reasons also. If the depth of working is reduced from 20 cm to 10 cm it is possible to cultivate double the area with the same power resources.

If deep ploughing is used (for the vetch and grain legume rotations) the cost will be higher.  Both the cereals and the vetch or grain legumes will require more power resources if the work is done on time. The cost of the whole rotation will increase and farmers may be reluctant to change.  Contractors may in the short term provide the extra resources at the same price. We stated earlier if the majority of farmers change to the new rotations the contractors will find they have no work in the spring and double the work in a short autumn period. They will change their charges to reflect the increased demand.

Shallow cultivation will be discussed in some detail later but the results have been variable in the WANA region.

In Libya, Iraq and Jordan it has been a great success. The reasons are:

    * Machines designed specifically for shallow cultivation have been purchased in Libya, Iraq and Jordan.

    * The extra power released by working to a depth of 10 cm instead of 20 cm has been used to pull wider machines.

    In other WANA countries shallow cultivation has been attempted using machines designed for deep ploughing.

They have performed badly. Weed control has been poor and farmers have become disillusioned with shallow cultivation.

In fact the machines should never be used outside their design specifications. It shows a poor understanding of the technology.

Shallow cultivation with deep ploughs has also failed to deliver more than a small part of the increased speed of cultivation.

Less power is needed but only a limited amount can be used to increase tractor speed over the ground. Unless wider implements are used shallow cultivation will not deliver double the rate of working. The design features of the implements used for shallow cultivation are explained in Buyer's guide to scarifiers.