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101

September 2018

Tillage implements

Tillage is the agricultural preparation of soil by mechanical agitation

of various types, such as digging, stirring or overturning. Tillage im-

plements are classified in primary tillage implements and secondary

tillage implements. Furthermore, tillage implements are also clas-

sified in conventional tillage and conservation tillage. Conservation

tillage (

Figure 2

) can also be divided into reduced tillage and no-till.

Conventional tillage practices require the most tillage operations

while conservation tillage requires less or no tillage practices.

Commonly used implements for conventional

tillage

Mouldboard plough

The mouldboard plough (

Photo 1

) is used for seedbed preparation

and forms part of the primary tillage actions. It is one of the old-

est of all agricultural implements and is generally considered to be

the most important tillage implement in conventional tillage prac-

tices. Ploughs can be categorised into mounted and semi-mounted

ploughs.

The drawbar power requirements for a four-share plough on sandy

soils will be 48 kW or 12 kW/share, at a working depth of 250 mm,

and a working speed of 5,9 km/h.

Disc plough

Disc ploughs (

Photo 2

) are most suitable for conditions under which

mouldboard ploughs do not work satisfactorily, such as hard dry

soils, in sticky soils where a mouldboard plough will not scour and

in stony fields. Disc ploughs depend on their weight to penetrate

into the ground and therefore are normally built from heavy mate-

rial. Side forces are usually taken up by the land-wheel at the back of

the implement.

The drawbar power requirement for a three disc plough at a working

depth of 250 mm is 45 kW or 15 kW/disc at a speed of 6 km/h.

Disc harrow

Disc harrows (

Photo 3

) rank close to the mouldboard plough in im-

portance as tillage implements. Heavy duty disk harrows are used

for primary tillage, for controlling weeds, and for cutting and mixing

stubble or cover crops with the soil. Lighter units are often used in

seedbed preparation subsequent to ploughing.

The power requirement to pull a light duty, 3 m cutting width disc

harrow at a working depth of 150 mm in sandy loam soil at a speed of

8 km/h, is 50 kW. The power requirement for heavy duty offset discs

with a cutting width of 3 m at 8 km/h is 80 kW.

Ripper or subsoiler

A ripper or subsoiler (

Photo 4

) is used to break through and shat-

ter compacted or otherwise impermeable soil layers and to improve

rainfall penetration. When practicing conventional tillage and using a

plough, a ripper will be used to break through the plough pan when

necessary.

The power requirement to pull a three-tine ripper on average is

60 kW or 20 kW/teeth at a working speed of 7 km/h and working

depth of 400 mm.

Cultivator

Cultivators (

Photo 5

) are used for weeding or seedbed preparation.

This specific model is called a Vibro Flex tiller, and is normally used

at an operation speed of 12 km/h to get the vibrating effect and

therefore maximum efficiency. It is also used to loosen the top layer

of soil to allow faster germination and enhance plant growth.

Depending on the working width of the implement, power require-

ments may vary from 40 kW to 100 kW.

Cultivator (s-tine with roller)

This implement (

Photo 6

) is used for light duty weeding and seed-

bed preparation. The roller at the back is used to break up the clots

to provide a fine seedbed for planting. The power needed to pull

the implement ranges between 40 kW and 80 kW, depending on the

working width.

For more information contact Dr Tingmin Yu or Johan

van Biljon at 012 842 4000.

1: Mouldboard plough.

2: Disc plough.

3: Disc harrow.

4: Ripper.

5: Cultivator.

6: Cultivator (s-tine with roller).

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