THE CEREAL CROP

Cultivation and seeding

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Better cereal yields and lower cost production

CHAPTER HEADING

SUMMARY

YOU ARE HERE

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.

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 cultivation for?

     The farmer cultivates the land in order to sow crops and pastures.

    * Most of the cultivated land will be sown to cereals.

    * Some will be sown to vetch and oats.

    * A small proportion to grain legumes such as lentils and chick peas.

    * Perhaps some will be sown to medic using seed. The amount will be small as pods provide a better alternative.

    After reading this section refer to  Costs and Returns for shallow cultivation  This may seem strange but until the use of shallow cultivation is understood it is not possible to explain the costs and returns.
 
 

The state of the land before cultivation.  

    * Cereal crops

With the fallow rotation the land is cultivated in the spring for a long summer fallow.

With all other rotations the first cultivation is in the autumn. Cereal crops will be sown on land that has previously been in medic pasture, a vetch/oat hay crop or grain legumes.

In all cases the crop residues will have been removed or eaten by livestock to a very large degree. The land will be easy to cultivate using conventional implements as there will be little residual trash to block tined implements. A three row scarifier should work well.

      * Other crops.

    Vetch/oats and grain legumes will be sown into the cereal stubble. At present in the WANA region these are well eaten by livestock and should not cause any blockage problems to tined scarifiers and seeders.

In future if better feed is available for livestock (as in Australia with medic pasture) less of the cereal stubble is eaten. The residues can cause problems for conventional designs (for example a standard three row scarifier).

Shallow cultivation with tined scarifiers should not be rejected in these situations. If the problem is anticipated machines designed to handle straw can be used. That is with their tines placed on four or more rows. They are slightly more expensive and unnecessary unless the problem exists.

      * Medic pasture.

    For sowing medic with seed into cereal stubble the straw problem (if it exists) can be handled in a "once only" way.

This is because the medic regenerates without re-sowing in future years. If straw is a problem is can be raked off or burnt. 

It is not worth purchasing tined implements to handle extra straw if this is the only time they will be used.
 

Preparing the implements.

     The scarifier is the main implement for cultivation when using shallow cultivation (see  Buyers guide to scarifiers ).

The scarifier should be prepared in late summer for the new season.

In addition to normal maintenance all the points on the scarifier should be changed.

New sharp points are needed for the first working of the land. The old points can be retained and used later in the season for secondary or further cultivation.

    The farmer should have a range of points available. Narrow points are better for penetrating hard ground the first time.

Wider points are better for cutting off weeds. Farmers will need to achieve a good balance between the two.

Commonly 10 cm points are fitted for the first cultivation and 15 cm points for the second. Alternatively on some soils it is possible to use 10 cm on the front row and 15 cm on the other rows. Farmers will over a few years develop their own system.
 

Cultivating and seeding systems.
 

    * Conventional tillage.

        This is a system in which tillage is the major means of weed control.

The land is cultivated with a scarifier two times and then again with a seeder during the sowing operation. Three cultivations in all.

This is a great deal less than conventional tillage using deep ploughing. With deep ploughing many operations are require after the initial deep ploughing to break down clods and to partly level the seedbed.

     * Reduced tillage.

        This system requires the use of some herbicides.

The land is cultivated with a scarifier and then cultivated and sown with a seeder. Two cultivations in all.

     * Direct drill.

    This system is more dependent on herbicides.

The land is cultivated and sown in a single operation using a scarifier/seeder.

     * Zero or no tillage.

    This system uses a modified seeder without cultivating tines.

The seed and fertiliser is sown directly into slits with minimum soil disturbance.


Chart 1

    Shows the runoff of rainfall in mm for four different cultivation and seeding packages.

Each package is divided into "bare soil before tillage" or "soil covered with straw."


    The above chart (based on experimental work conducted in Australia) compares the four systems of cultivation and seeding in terms of potential soil erosion.

In the WANA region it is unlikely that 1500 to 2000 kg of straw would remain after summer grazing by livestock.

The higher run off from bare soil would be a closer representation of the situation.
 

The first operation with the scarifier.
 

    * Timing.

    The first operation for the reduced tillage system and the conventional tillage system is to cultivate the land with a scarifier.

This is done after the first rain.

Dry cultivation before the autumn rain is expensive. More tractor fuel is required and the points wear rapidly. It plays no part in weed control and is not recommended.

The first cultivation should be delayed for a few days after the rain to allow the seeds in the ground to germinate. This will produce a better weed kill.

    * Depth of cultivation.

    Depth of cultivation will be 7 to 10 cm. when the ground is level.

Depth control chains should be fitted to the scarifier to indicate this range.

The short chain indicates 10 cm and the long one 7 cm. The long one should touch the ground and the short one swing free. 

If both touch the ground it is too deep. If both swing free it is too shallow.

Linkage scarifiers should be fitted with depth wheels. It is not possible to control the depth accurately using the hydraulic controls on the tractor alone.

Farmers have used linkage cultivators in the past without depth wheels but the depth had already been set by the previous deep ploughing. In the case of the scarifier this is the first cultivation and working too deep is a waste of time and energy. Working too shallow will not cut off weeds.

Where the land has been deep ploughed for many years the scarifier should be worked deeper.

This is because of the waves left by years of deep ploughing. A 7 - 10 cm depth will be insufficient where the scarifier straddles a trough. It is necessary to work to a depth of 15 cm to ensure all the land is cultivated to a depth of 7 cm. Over a few year the scarifier (and harrows) will level the waves and a 7 to 10 cm depth can be used.

    * Harrows behind scarifier.

    The clods produced behind the scarifier that is working a few days after the first rain should be soft.

It is a good idea to pull a harrow behind the scarifier to break the clods before they have time to dry and harden.

The harrow needs to be sufficiently heavy to pull the clods up and batter them about. A light harrow will drop the clods back into the ground and bounce over them.

The harrowing can be done as a separate operation but it is better as a single operation as it conserves moisture.

Every time the land is cultivated and exposed to the sun and wind the surface will dry out. Even a few hour or a day will dry the surface to some degree.

If the harrows are pulled directly behind the scarifier there is no loss of moisture in this way.
 

The second and subsequent operations with the scarifier.
 

    * Timing.

    The second cultivation with the scarifier is carried out ten day or two weeks later when, ideally, there has been more rain and a further germination of weeds.

    * Depth of cultivation.

    The land should be cultivated to the same depth of 7 to 10 cm for level ground and 15 cm for land that has been deep ploughed in the past and has waves.

The depth control chains are needed. The depth control wheel will need to be reset as the ground is now softer and the wheel will sink in further.

    * Adjustments to the scarifier.

    The points on the scarifier will need to be changed.

Wider points should be used. The ground has been broken open by the first cultivation and it is now essential to cut off all the weeds completely.
   

The second cultivation with the scarifier requires less power than the first. The operation can be carried out faster.

There is a limit to the speed of operation. Excessive speed will throw the soil around and create more pronounced ridges and furrows behind the scarifier.

This will make it more difficult for the harrows to operate as clod breakers.

The scarifier can be modified at this stage by the addition of bolt-on tines. An additional tine can be bolted on each side to convert, for example, a 13 tine scarifier into a 15 tine.

    * Harrows.

    Use the harrows behind the scarifier.

The harrows will complete the job of weed control.

The scarifier will pull the weeds out of the ground and the harrows will knock the soil out of their roots and leave them on the surface to die of dehydration.
 

Using herbicides.
 

    * Instead of cultivation.

    Herbicides can be a most effective means of controlling weeds and reducing soil erosion (see chart above).

To make the best use of herbicides they should be used as an alternative to cultivation.

The farmers should try to anticipate the weed problem and apply the herbicide as a pre-emergent.

It is costly to try to control weeds with cultivation, fail and then apply the herbicide.

If this system is adopted on a permanent basis farmers can save a considerable amount in capital expenditure on tractors.

    * Broad leafed weeds.

    The simplest use of herbicides is to control broad leafed weeds in the cereal crop after the crop has reached the tillering stage.
 

Time of sowing.
 


Chart 2

The figure below shows the results of an experiment conducted at El Marj in the Jebel al Akdhar region of eastern Libya (South Australian Government Demonstration Farm Report 1974-79)
 


  The experiment was conducted as follows:-

    * All the land was cultivated with a scarifier before the first rain. This did not control weeds and can be ignored.

    * On 2nd November the first treatment was sown to cereals. If the dry working is ignored this becomes the equivalent of the "direct drill" in the chart above on soil erosion.  No herbicide was used. Weed control was poor and yield was the lowest of all treatments. On the same day all the other treatment were cultivated with a scarifier (2nd cultivation)

    * On 27th November another treatment area was sown using the tined seeder. This can be regarded as the equivalent of "reduced till." The other treatments were cultivated with a scarifier. (3nd cultivation) Yield improved due to better weed control.

    * On 13th December another treatment was sown using the tined seeder. This is equivalent to the "conventional tillage." That is two (effective as the first was dry and has been ignored) cultivations with a scarifier and then seeding with the tined seeder. The yield was the best of all treatment. At the same time the other treatments were cultivated with a scarifier to control weeds.

    * On 6th January (Presumably the Australians took a short Christmas break! This treatment should have been sown on 27th December) another treatment was sown. Yields began to fall due to late sowing in spite of better weed control. The last treatment was cultivated again with a scarifier.

    * On 26th January the last treatment was sown. Yield was reduced further due late sowing in spite of good weed control.

    The experiment demonstrates the need to achieve the optimum balance between weed control and early sowing.
 

Other evidence from Australia

    Research work carried out in the lower rainfall parts (250 to 350 mm) of the Australian cereal zone have shown that wheat yields decline by 17 kg/ha per day if sowing is delayed after 15th April.

Converted to the northern hemisphere that is after 15th October.

Potential yields of Wyalktchem wheat at Kellerberrin in the Western Australian wheat belt for the season 2007

Sowing date

Soil water at sowing (modelled) in mm.

Chance of excessing the yield below (qx/ha)

Southern hemisphere
Northern hemisphere
in 1 year out of 4 High yields
in 1 year out of 2 Average yields
in 3 year out of 4 Poor yields
April 20
Oct 20
0
Not sown
May 10
Nov 10
8
31
22
15
May 25
Nov 25
7
28
19
13
June 5
Dec 5
16
25
16
11
June 10
Dec 10
22
23
15
10.5
June 20
Dec 20
32
20
13
10

Source: CSIRO Sustainable Systems.

The table above shows the advantages of early sowing but unlike the experiments carried out at El Marj in Libya there is no attempt to examine the interactiion between weed control and sowing date.

The above results are part of a computer modelling service developed by the Birchip Farming Group.

More information is available in Modelling

or at www.yieldprophet.com.au

Seeding method
 

    * The tined seeder.

    The experiment shown below was conducted on the ITGC research centre at El Kroub in eastern Algeria  (Nelson 1980).

It compared the tined seeder (Shearer, Australia) with a disc seeder ( Nordsten, Denmark).

The make of the seeders is not important nor their country of origin.

The superiority of the tined seeder in this experiment was due to its superior weed control.

The tines carried out a most effective cultivation of the land at the same time as the seed was sown. Harrows behind the seeder knocked the soil from the roots of the weeds and left them on the surface to die of dehydration.


Chart 3


 

       While the tined seeder is more expensive the yield increases shown above demonstrate that it is a good investment.

There are other savings using a tined seeder which are described below.
 

Fertiliser.
 

     * Fertiliser placement.

    Many farmers (particularly small farmers) in the WANA region do not use fertiliser because they consider the risk too great.

The tined seeder places the fertiliser and the seed together in the sowing tube and then in a band in the soil.

The placement of the seed and fertiliser together improves the response. Smaller quantities of fertilisers will produce a similar response. Farmers will find the risk much less.

In the 1890s when phosphate fertiliser was first introduced into South Australia fertiliser placement was the key to its adoption.

The original research at Roseworthy had shown good responses to phosphate fertiliser. The fertiliser was broadcast at rates of 300 kg / ha and more in the experiments and these rates were recommended to farmers.

Farmers found the cost and the risk too great and little fertiliser was used.  A farmer discovered that a similar response could be achieved with 100 kg / ha of phosphate (single super phosphate not triple phosphate) if the fertiliser was placed with the seed.

Fertiliser was quickly adopted by farmers. Within a decade 85% of cereal crops were sown with phosphate.

    * Fertiliser type.

    Fertiliser placement is perfectly safe with all types of phosphate fertiliser.

When the medic-cereal rotation is used that is the only fertiliser needed. The medic pasture provides ample nitrogen for the cereal crop.

If vetch or grain legume are used some additional nitrogen may be required. These legume crops produce nitrogen but a large part is removed with the hay or grain. Additional nitrogen may be required.

It is important that the fertiliser type is compatible with placement. For example DAP (Diammonium phosphate) can be used but urea will reduce germination.

Alternatively a more expensive tined seeder can be purchased with two tubes for each tine. One is for seed and one for fertiliser. They are sown at different depths and while placed in close proximity are not actually in contact.
 

Seeding rate.
 

    Seeding rates can be reduced considerably when the scarifier and tined seeder are used over a few years.

Seeding rates are commonly over 100 kg /ha in WANA and can be reduced to 70 kg/ ha and less depending on the rainfall zone.

The reduction in seeding rates is due to a better and more even germination of the seed. Once the land has been levelled and the waves caused by deep ploughing removed the seeder will operate more efficiently.

The tined seeder has a greater ability to penetrate the ground and will sow at a much more even depth than the disc.

The savings to the farmer are considerable.

Cereal seed is more expensive to purchase than cereal grain sold. A reduction of seeding rate from 120 kg /ha to 70 kg /ha will save the farmer 50 kg / ha in seed.

In terms of profit this is the equivalent of a yield increase of at least 100 kg /ha.
 

Harrows behind the seeder.
 

    Usually light harrows are pulled behind the seeder to level the ridges and furrows left by the tines.

This will provide a good level surface for further operations.

Herbicide application is faster and more efficient.

Harvesting is also faster and more efficient.
 

Other crops
 

     * Vetch and oats for hay.

    The tined seeder is particularly useful for vetch and oats.

In many cases where weeds are not a serious problem vetch/oats can be sown using the tined seeder in a single operation.

It is a direct drill system.

Herbicides are not needed as a limited amount of weed in the crop can be tolerated. If the weeds are palatable grass weeds they can be cut for hay with the vetch and the oats.

Using the tined seeder in this way saves cultivation costs and allows the crop to be sown early.

    * Grain legumes.

    These will require much better weed control.

They will be sown using the conventional tillage system. That is two scarifier cultivations followed by a tined seeder.

Alternatively herbicides and fewer cultivations. The great advantage of scarifers is that the land is level. A passage with a roller will make the surface suitable for mechanical harvesting of grain legumes.
 

Priority cultivation and seeding
 

     On almost all farms there is a large variation in the quality of the soil.

Farmers should give priority to their best land with the greatest yield potential.

This should be cultivated first. When it is time for the next cultivation this should be done on time even if all the other poor land has not been cultivated.

Return to the good land again for optimum sowing.

If the poor land is falling behind farmers may use herbicides or if it has not been cultivated at all leave it for medic pasture.
 

Contour Banks
 

Contour banks have been built in the WANA region on slopes to control erosion.

They can be quite effective.

One of their disadvantages is that they produce awkward shaped areas for cultivation.

With deep ploughing the problems of the waves and troughs can be mitigated if the cultivated area is perfectly regular and the ridges and furrow are exactly parallel.

This is absolutely impossible with contour banks and shallow cultivation with scarifiers is the optimum method of seed bed preparation.
 

Scarifier - seeders.

    See  Buyers guide to scarifiers  for more details.

For many farmers scarifier - seeders are a better option but we have used separate implements in the above chapter for the sake of simplicity.
 

Photos of the implements in action
 

    I have not place these in this file as it would be too large and difficult to down load.

They can be accessed through Farmer Training Kits but I would recommend a CD for the photos themselves if you are considering printing them for extension material.