 |
Tillage machinery The term 'tillage' is widely used to describe operations which prepare the soil for crop establishment, but the term 'cultivations' has also a similar meaning.
There are two main stages in cultivations : primary and secondary.
Primary Cultivations: The main objectives of this first stage in soil disturbance are to invert or turn over a slice of the topsoil, burying weeds, surface trash or manures spread on the surface and to break up the soil to a depth of up to 20 cm in order to encourage aeration y, water penetration and to generally prepare the soil for the secondary operations.
Secondary cultivations: These are mainly directed towards the preparation Of a tilth, a term used to describe the surface layer of a soil which has been subjected to movement or pressure so that it is well broken up and free from large lumps or clods of soil. Such a surface is most suitable for the uniform sowing and covering of seeds, transplanting seedlings or
planting tubers and is favourable to the rapid establishment of crop root systems. In tropical areas, it is generally considered unwise to cultivate soils unnecessarily. This is due to the fact that, particularly on silty soils, heavy rainfall breaks down the soil surface, causing 'capping' or the formation of a crust of hard soil on drying. This can seal the soil surface, preventing the exchange of gases such as oxygen and carbon dioxide between the atmosphere and the soil air. Roots require oxygen for respiration and growth and an excess of carbon dioxide, produced by soil bacteria,
can be harmful to plant roots. It has been found that many tropical crops can be successfully established by sowing the seeds in fairly rough seed beds.
Primary and secondary cultivation equipment may be grouped into mouldboard, disc and tined imple-
ments, which are either trailed or direct mountcd by a three-point linkage on the tractor, plus operations
Tractors
With the development of commercial agriculture, the use of machinery has increased to the extent that operations which were previously carried out by manual labour are now part of a mechanised crop production system. This has enabled larger areas of land to be cultivated and has reduced the time spent on some operations such as seed sowing, weeding and harvesting. In many instances, mechanisation has led to increased crop yields, owing to the fact that various operations can be carried out at the most suitable period in the cropping cycle.
The small farmer, however, is rarely in a position to purchase machinery or equipment for his own use, and, if they are available, he relies more and more on hiring the tractors and machinery which will reduce the time and labour he spends on operations such as soil preparation, seed sowing, applying fertilisers, crop spraying and harvesting. Much of this machinery
is made available through machinery hire contractors and many governments sponsored schemes.
Also Read:
Tractor ploughing is becoming more common, particularly on flat land where the soil is relatively deep and free from stones or tree stumps. Large petrol or diesel-powered tractors can draw a wide range of implements, many of which can be attached to the tractor, by a three-point hydraulic linkage which enables the implement to operate at a constant depth. This linkage, which is operated by the hydraulic mechanism of the tractor, also allows for the rapid attachment of a wide range of equipment which can be lifted or lowered while the machine is in operation.
Implements which can be attached to a hydraulic linkage are referred to as tractor-mounted implements.
Other implements, however, are drawn behind the tractor, attached to a drawbar, and these are referred to as trailed implemented.
Routine Tractor Maintenance
Regular maintenance is essential if a tractor and associated implements are to be kept in good working order. Instruction books, supplied by the manufacturer, should be followed in detail by drivers and maintenance staff responsible for routine repairs, adjustments and servicing.
A properly kept log book, filled in by the tractor operator to record hours worked, is the best means of ensuring that servicing and maintenance are carried out at the correct intervals. Records of fuel and oil used should also be entered in the log book.