THE CEREAL CROP

The stripper

A low cost alternative harvester for small farmers

in the WANA region

HomeFARMING ZONES IN WANAGuide to cereals and pasture >   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.

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.

YOU ARE HERE

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

What is a stripper?

    A stripper is a low cost cereal harvester that is well suited to small farms.

Diagram 1.

    Diagram 1 show the main elements of a stripper.

+ The COMB FRONT (Comb fingers plus knife) enters the cereal crop. The crop is collected and cut.

+ The thresher drum is mounted above the knife. The material is threshed at the same time as it is cut.

+ The grain, chaff and straw is flung back into the transport box by the action of the fast moving thresher.

+ When the box is full it is transported to the farm house or dumped in the corner of the field.

+ The back door is opened. The box it tipped using a simple hand operated winch.
 



What does it do?

    The stripper carries out the following tasks:-

    + It harvests the cereal crop. As a COMB FRONT is used the stripper can operate efficiently in low yielding crops with little loss of grain.

    + It threshes the grain from the straw and chaff.

    + It transports the grain, chaff and straw to the farm house.
 

How is it powered? 

    The stripper shown in Diagram 1 is the one developed in Australia for use with a tractor.

It was powered originally with horses (during the 19th century) and then pulled by a tractor.

The knife and thresher were powered from the ground wheel.

This is certainly a cheap machine but it is not easy to turn in sharp corners.

    For the WANA region a self propelled version with a small 5 H. P. engine would be more practical. It would be more easily manoeuvred in small fields.
 

Why is it called a stripper?

    The original strippers invented in the first half of the 19th century in South Australia did not have a knife.

The grain and chaff was stripped from the heads by the thresher.

Later it was found to be more efficient to add a knife behind the comb fingers.
 

What happens next? 

    The grain, chaff and straw are dumped at the farm house.

They need to be separated. This can be done in a number of ways.

    Traditional methods.

    The separation can be done using the wind and sieves.

This is slow but there is no hurry.

The task can be carried out over the summer as the grain is safe from damage in the chaff and straw. For a small farmer with only  a few tonnes of grain this is a satisfactory method.

The separation can be made more consistent by using a small hand powered fan as used in India.

   A portable winnower.

    Alternatively a winnower can be used.

This is a stationary machine that separates the straw and chaff from the grain in a similar manner to the combine harvester.

Why not use a combine harvester?

The portable winnower is a small machine and many cheap versions are available in India and other countries. 

As there is no urgent time constraint for separation after harvest so it can be shared among many farmers.

They can harvest their crops and then the portable winnower can move from farm to farm over the following months cleaning the grain.

This is a simple winnower for cleaning the chaff from the grain.

As it is a stationary machine breakages are low and it can be shared or hired without an operator.

    The combine harvester.

    A third alternative is to use the combine harvester.

Again what is the point?

Why not use the harvester from the beginning?

The combine harvester can be used after all the other harvesting has been done.

The farmer should be able to negotiate a good rate for this out of season work. The combine harvester has the front removed. The straw, chaff and grain is fed through the machine with the thresher set as open as possible in order to prevent the grain from being cracked by double threshing.
 

What are the advantages?

    Low capital cost.

    The stripper is a real small machine.

It is not a large harvester produced on a small scale.

It is cheap because it has so few moving parts. Only the knife and the thresher are power driven.

    High efficiency.

    The comb front is a very efficient means of harvesting the crop. It is comparatively more efficient in low yielding crops.

By definition the total crop is then saved. There are no losses at all in the separation process.

    Small size.

    The stripper is limited to a width of 2 m. This is the maximum practical width for the thresher drum.

The small size is an advantage for small fields, for harvesting between olive trees and many other situations on small farms.

    Easy to operate.

    The stripper is a very simple machine. It does not require a great deal of operator training.

Farmers and farmer machinery groups could easily operate the stripper.

    Easy to clean.

    Small farmers have different cereals in different fields.

Cleaning the machine between fields is important if durum wheat is not to be contaminated with barley.

Cleaning a combine harvester is a tedious business. Elevators have to be opened and the grain collected.

The stripper is virtually self cleaning each time it is emptied.

    Transports grain, chaff and straw.

    These are all important to the small farmer.

They are transported by the stripper.

There is no need to reload the material from the chaff cart.

   Transports weed seeds.

    The weed seeds are transported. None fall on the ground.

There is no need for a separate weed control operation in winter.
 

What are the disadvantages?
 

    Low labour productivity.

    Compared to the combine harvester the labour productivity is low.

As the labour used is family labour this is not important for small farmers.

In fact it can be argued that small farmers would prefer to carry out the harvesting themselves rather than pay a contractor.

    Additional work.

    The stripper does not separate the grain from the chaff and the straw.

This is an additional task. If it is carried out with family labour during a period when their are no other important jobs on the farm it is not an expense the farmer pays for in cash.

    Requires hot weather.

    The stripper will operate well in the WANA region because summer temperatures during the harvest season are above 28 degrees C.

Below this temperature the thresher is not efficient.

My great great grandfather attempted to transfer the stripper technology to England from South Australia in the 19th century but found that the machine did not work because summer temperatures were only above 28 for a few days and a few hour each day.

There have been more recent attempts to revive the stripper.

While it is admitted that the stripper is a much cheaper machine than a combine harvester it does not have the capacity of the combine harvester.

These strippers have been designed as competitors to the combine harvester not as alternative machines.

They carry out complete separation in the field  - that is they treat the straw and chaff as waste products.
 

Cost - benefit comparison.
 

    This comparison is extraordinarily difficult as the two types of harvester are for such different purposes.

     Harvesting efficiency.

    The stripper is overwhelmingly more efficient than the combine harvester on small farms and with low yields.

The comb front is more efficient than existing combine harvester with their open fronts.

It is probably more efficient than modified combined harvesters in collecting the crop.

    + It is more efficient on uneven ground because the front width is only 2 m.

    + It is more efficient in small fields and around trees and other obstacles.

    + It has zero loss through the machine.

    The combine harvester is particularly inefficient on small farms as many types of crops are harvested. Operators barely have time to adjust their machines to a particular crop before the field is finished.

Many crops are harvested after the optimum time because it is impossible to bring the large combine harvester onto small farms for individual fields. Instead the whole of cereal production is harvested at the same time.

    Labour productivity.

    This is the method of comparison used in countries with high labour cost and large farms.

Combine harvesters vary in size and capacity but it would not be an exaggeration to claim that one combine harvester could harvest between 50 and 100 times the amount harvested by a stripper in an hour.

    This assumes:

    + A high yielding crop where the combine harvester is working at its full capacity.

In the WANA region we need to discount this figure by a large factor because average yields are low.  Instead of crops averaging 5 to 10 tonne per hectare as in Europe national averages for dryland crops in WANA are less than 2 tonnes with many districts averaging less than 1 tonne per ha.

It is impossible to harvest these low yielding crops at the high speed required to fill the combine harvester to capacity. Immediately the combine harvester is perhaps only 10 to 20 times more productive.

    + It also assumes that the combine harvester is working in large fields.

Once the combine harvester is used on small fields and moved between different crops and owners its labour productivity fall again. Another discount on productivity is required.

    The other difficulty in measuring the labour productivity of the two types of harvester is the value of the chaff and straw.

The combine harvester is built for specialised cereal production where straw and chaff are waste products.

On small farms in the WANA region they are a valuable resource.

The stripper is slow because it also carries out the task of the chaff cart but much better.

The combine harvester fitted with a chaff cart dumps the straw and chaff in heaps that need to be reloaded. The chaff and straw is then transported to the farm house.

The stripper takes the straw, chaff and grain to the farm house in a single operation.

    If one were to make a labour productivity comparison between the combine harvester for grain, chaff and straw compared to the stripper the productivity would be more evenly matched.

    Capital productivity.

    The stripper is not a scaled down version of the combine harvester.

Instead of hundreds of moving parts it has only two or three. It is therefore quite productive in terms of output per unit of capital.

Again comparisons are hard as strictly speaking the output is not grain as with the combine harvester and one has to bring in the separation process to compare the machines on equal terms.
 

    Costs and returns - a summary.
 

Table 1.

A comparison of the stripper and the combine harvester on small farms.

On large farms the combine harvester is the obvious choice. 

STRIPPER

COMBINE HARVESTER

Less pre-harvest loss. More likely to be used at the optimum time.

Some crops past their optimum maturity.

Less harvest loss. Comb front more efficient with light yielding crops. Able to harvest into corners and over rough ground.

Open front less efficient with yields less than 3 tonne per ha. Even modified open front not as efficient as stripper. Cannot harvest in corners and around trees.

Zero loss through machine.

Some loss through machine unless chaff cart attached. Chaff cart hard to handle in small fields. Losses can be high because frequent changes in crop type needs frequent adjustments. 

Labour productivity low if measure against harvested grain.

Labour productivity high when measured against grain output provide yields are high and fields are large.

Labour productivity more reasonable when measured against harvested grain, chaff and straw for use by livestock at the farm house. 

Labour productivity for these other tasks separate operations. Baling of straw and carting of chaff and straw from dumps. 

Labour used is family labour with a low opportunity cost.

Labour used is expensive contractor labour that must be paid in cash.

Capital costs low. Feasible for small farmer or farm machinery group. Capital efficiency also good. That is capital per tonne harvested.

Capital cost extremely high. Large farmers and contractors. Must be used over large areas to justify cost. Small farmers likely to be on end of list for contract services. Pre-harvest losses for small farmers will be higher.

Separation of grain from straw and chaff an extra operation and cost. Can be done during summer when there is no urgent seasonal work to be done.

Combine harvester also cleans grain to a high standard but at the cost of wasting the other products.