1. MARKING OUT
Good, even ploughing is important, either with a mouldboard or 2 disc plough as a land that has been ploughed well requires fewer cultivations and levelling to obtain a good seedbed. Good ploughing saves the farmer money that would be spent on after-cultivations, and crops grow better in soil that has been ploughed to an even depth. When a conventional mouldboard or disc plough is used, soil is moved from left to right, unploughed land is always on the left of the tractor and ploughed furrows on the right. In order to make sure that a plough always has a furrow on its right, and the minimum time wasted in idle running or making awkward turns, ploughing must be done accurately to a pre-arranged plan or layout. This is usually done by ploughing in ‘lands’ as shown below.
Figure 1: A planned layout of a ploughed land
Ploughing starts with the ridges and ends with the finishes. When ploughing a land that is enclosed by a hedge or tree line, a headland is left around the outside, and this is ploughed last. The headland should be 6 metres wide for a 2 or 3 furrow plough, and 1 metre more for each additional furrow. A headland of this width allows the tractor and plough to turn easily when entering and leaving the area.
When ploughing the main body of the land, two methods are used. These are gathering and casting. Gathering is done by working around the opening ridge, with the tractor always turning to the right. Casting is done with the tractor always turning to the left and working between two opening ridges and ending with a finishing furrow. Normal ploughing is done using both these methods, but long narrow lands can be ploughed by casting or gathering alone. Such lands should be ploughed by complete gathering one season and complete casting the next season to avoid building a large ridge in the centre of the land.
Figure 2: Gathering and Casting of a field
Figure 3: Marking out the headlands and marking out the ridges
The first operation in ploughing an enclosed land is to mark out the headlands. The driver should cut a number of long sticks or marking poles, walk around the land placing a stick at each corner the correct distance from the boundary. He then ploughs a single shallow furrow around the land to mark the headland, turning the furrow into the land. When using a plough with two or more bodies, only the rear body is used to cut the furrow, the remainder being raised clear of the ground.
After marking out the headland, the next step is to mark out the ridges. The distance between ridges will depend on the size of the plough being used, and should be 20 metres for a 2-furrow, 30 metres for a 3-furrow and 40 metres for a 4-furrow plough. In this way the field is divided into smaller ‘lands’ for ploughing, so that time and fuel are not wasted. The marking sticks are moved over from
the headlands to the line of the first ridge which is placed three quarters of a full land width from the headland. Having ploughed out the first ridge with a single shallow furrow, the marking sticks are moved over to mark the second ridge, and this is continued until all the ridges have been marked out. The distance between the ridges can be paced out at right angles to the last ridge that has been ploughed out. It is most important to make sure that all the ridges are straight and parallel to each other, otherwise the finishing furrows will be very uneven and the ploughed field will look untidy. It is also important to see that the marking furrow of any ridge is cut with the full share width of the plough.
When all the ridges have been marked out with a single shallow furrow, the next stage is to complete them so that ploughing of the field can begin. One method of doing this is called the ‘double split’, and it is used on arable land that has grown a previous crop. The steps for this are shown below, using a 3-furrow plough.
Figure 4: Steps for ploughing a land using the double split method
As the last ridge is marked out, the driver makes a complete loop turn and goes down the furrow in the opposite direction, turning a single furrow with the rear body, and leaving a narrow strip of un-ploughed land. This strip of land is broken by the tractor wheel during later operations.
After completing the last ridge, the tractor does another loop turn and all 3 plough bodies are set to plough a furrow. The front body ploughs a shallow furrow, and the rear body is set to plough at almost the full working depth. The front body turns a ‘sandwich’ made up of the shallow furrow slice turned out in marking the opening, together with a fresh slice underneath it which should be slightly deeper. This is done both up and down all the ridges, finishing at the original starting point of the first marking furrow. At this stage, the ridges are complete, or ‘set up’, and each ridge consists of six furrows. The next time the plough goes down any of the ridges it will be at full working depth, and the centre of each ridge will be no higher than the rest of the ploughing.
Single split method of making ridges
An alternative to the double split is the single split method of making the ridges. In this method, the ridges are marked out as before with a single shallow furrow. At the end of marking out, the driver makes a complete loop turn and comes down the ridge in the opposite direction with the off-side tractor wheel on the furrow slice. This packs down the furrow and seals off the unploughed strip of land underneath. At this stage, all 3 bodies should be in the ground, with the front body set shallow, and the rear body ploughing at almost the full working depth. After completing this operation, the driver makes another loop and cuts another 3 furrows in the opposite direction. This completes the ridge, and the marking furrow is now buried under two shallow furrows each ridge consists of 6 furrows. Ploughing will now be done at the full working depth, and the ridges will be no higher than the rest of the ploughing.
Figure 5: A Complete single split ridge
Ploughing the land using a continuous ploughing method
After completing the marking out and setting up of the ridges, the land is then ploughed by gathering and casting using the continuous ploughing method which has been designed to produce tidy, economical ploughing. The steps to follow in using this method are shown in the following diagrammes.
Figure 6: Step 1 of ploughing the land using a continuous ploughing method
Starting from the headland, the ground between this and the first ridge is ploughed out by casting. When one quarter of the ground remains to be ploughed, a shallow furrow is cut on the headland side, and ploughing continues by gathering around the ridge.
Figure 7: Step 2 of ploughing the land using a continuous ploughing method
Gathering continues until three quarters of the ground remains unploughed between the first and second ridges. At this stage, the first finishing furrow has been completed between the headland and the first ridge. Ploughing is continued between the first and second ridges by casting.
Figure 8: Step 3 of ploughing the land using a continuous ploughing method
When one quarter of the ground between the last two ridges remains unploughed, this should match the half and between the last ridge and the headland, and is ploughed out by gatherings.
Figure 9: Ploughing a finishing furrow
The steps to follow when ploughing the finishing furrow are shown above. Making a good finish is the most difficult part of ploughing, and it is important to watch these points carefully.
- Leave a shallow open furrow on one side of the land and work up to this from the other side. This furrow is left at the point where the ploughing changes from casting to gathering.
- Keep the lands straight and parallel. This depends on good marking out, and accurate
ploughing with the front furrow always the same width as the other furrows.
- Correct any inaccuracies as soon as possible. When the unploughed strip is about 10 metres wide, a check should be made by pacing across it in 2 or 3 places. When the land is reduced to 5 metres it should be checked again very carefully.
- Reduce the width of the unploughed land to 1 furrow-width less than that of the plough being used. When a 3-furrow plough is being used, the final unploughed strip of land should be 2 furrows wide.
- Plough out the final piece of land with the 2 front plough bodies, and use the rear body to cut a shallow ‘earth furrow’ in the furrow bottom.
- PLOUGHING THE HEADLAND
Figure 10: Shows how the headland is ploughed
The three illustrations on page 32 show how the headland is ploughed out, turning the furrow in towards the centre of the field. The ploughing should be done without lifting the plough at the corners, but the corners should be taken very slowly. Corners can be filled in by taking a few ‘short turns’ in the opposite direction to the main headland ploughing.
The illustration above shows the headland being ploughed towards the inside of the field, the corners being filled in the same way, but this time in the direction of the main ploughing. If a headland is ploughed towards the centre of the field one year, it should be ploughed in the opposite direction the next year, to avoid forming a ridge and a hollow on the outside of the field.
The two illustrations on page 34 show that a small and large obstruction can be ploughed around so that the minimum of land is left unploughed.
Figure 11: Shows how one should plough when there is small and large obstruction
Figure 12: How one should plough an enclosed field with an irregular shape
The illustration in figure 12 shows how an enclosed field with an irregular shape can be ploughed. The principle is exactly the same as for other ploughing, but allowances are made for the shape of the field.
4. ROUND AND ROUND PLOUGHING
This system is used to avoid having ridges and furrows on the ploughed land, and where a level surface is required. It is best carried out on lands with a fairly regular shape. In order to achieve good results, the centre of the field must be marked out very carefully, and should be an exact replica of the shape of the field. A large headland should be marked out, and when there is no longer room to make a loop turn at each corner, the remaining land can be ploughed out as a headland.
Figure 13: Shows round and round ploughing
5. ONE-WAY PLOUGHING
This system requires the use of a one-way or reversible plough which can be reversed to turn a furrow either to the left or the right. After the headland has been marked out, the driver should drive down a straight mark at the side of the land, turning the furrow out towards the headland. At the end of the row, he turns the tractor in a loop turn, reverses the plough and returns down the same furrow. In this way, the whole land can be ploughed by starting at one side of the land and working across to the other side.
The advantages of this system are that the land is left level and very little time is spent in marking out and none in finishing. Furthermore, this is the best type of plough to use when ploughing across slopes and between contours, as all the furrows can be turned in the same direction.
6. MINIMUM TILLAGE
The only soil disturbance is during planting and is limited to the planting strips, generally accepted as being not more than 15% of the soils surface. This practice leaves large areas of the soil surface covered witht eh crop stubble or mulch.
Other terms used to describe this method are strip tillage and zone tillage.
As shown in the picture on the next page (Figure 14), only the lines that are intended to be planted
are tilled lightly, leaving the majority of the land undisturbed. If compaction is an issue, a ripper could be run through the land. This does not turn the soil over, exposing it to the elements but breaks up the compacted soil and allows water to penertrate deeper into the soil profile.
The advantages of minium tillage are as follows:
- Reduction of wind erosion;
- Reduction of water erosion;
- Control of weeds and insect pests; and
- Reduction of machinery and fuel costs.
The main disadvantage of minimum tillage is the possibility of leaf diseases being carried over from one crop to the next via the crop stubble.
Figure 14: A land that has been strip tilled