Different types of plough are used at different places. They may be classified as: 1. Indigenous Plough 2. Mouldboard Plough 3. Disc Plough 4. Chisel Plough 5. Sub Soiler 6. Rotary Plough.
Type # 1. Indigenous Plough:
Indigenous plough is most commonly used in this country. The shape and size of the plough varies with places and regions due to variation in soil types and tillage requirements. The main parts of the plough are – (a) Body, (b) Share, (c) Shoe, (d) Beam, and (e) Handle.
Body is the main frame to which the shoe, beam and handle are attached. Share is a narrow steel bar attached to the upper surface of the shoe longitudinally along the centre line and the handle is generally attached to the body of the plough. The share is attached to the shoe which penetrates into the soil and breaks it open. The shoe also helps in stabilizing and balancing the plough while in operation. The plough is provided with a wooden beam and a handle.
Type # 2. Mouldboard Plough:
A mouldboard plough is very common implement used for primary tillage operations. This plough performs several functions at a time.
i. Cutting the furrow slice
ii. Lifting the soil
iii. Turning the furrow slice and
iv. Pulverising the soil
Type # 3. Disc Plough:
It is a plough which cuts, turns and in some cases breaks furrow slices by means of separately mounted large steel discs. A disc plough is designed with a view to reduce friction by making a rolling plough bottom instead of sliding plough bottom. A disc plough works well in the conditions where mouldboard plough does not work satisfactorily.
Advantages of Disc Plough:
i. A disc plough can be forced to penetrate into the soil which is too hard and dry for working with a mouldboard plough.
ii. It works well in sticky soil in which a mouldboard plough does not scour.
iii. It is more useful for deep ploughing.
iv. It can be used safely in stony and stumpy soil without much danger of breakage.
v. A disc plough works well even after a considerable part of the disc is worn off in abrasive soil.
vi. It works in loose soil also (such as peat) without much clogging.
Disadvantages of Disc Plough:
i. It is not suitable for covering surface trash and weeds as effectively as mouldboard plough does.
ii. Comparatively, the disc plough leaves the soil in rough and cloddy condition than that of mouldboard plough.
iii. Disc plough is much heavier than mouldboard plough for equal capacities because penetration of this plough is affected largely by its weight rather than suction. There is one significant difference between mouldboard plough and disc plough i.e. mouldboard plough is forced into the ground by the suction of the plough, while the disc plough is forced into the ground by its own weight.
Types of Disc Plough:
Disc ploughs are of two types:
I. Standard Disc Plough and
II. Vertical Disc Plough
I. Standard Disc Plough:
It consists of steel disc of 60 to 90 cm diameter, set at a certain angle to the direction of travel. Each disc revolves on a stub axle in a thrust bearing, carried at the lower end of a strong stand which is bolted to the plough beam.
The angle of the disc to the vertical and to the furrow wall is adjustable. In action, the disc cuts the soil, breaks it and pushes it sideways. There is little inversion of furrow slice as well as little burying of weeds and trashes. The disc plough may be mounted type or trailed type. In mounted disc plough, the side thrust is taken by the wheels of the tractor. Sometimes a rear wheel is fitted to take side thrust of the plough to some extent.
In trailed type, side thrust is taken by the furrow wheel of the plough. Disc is made of heat treated steel of 5 mm to 10 mm thickness. The edge of the disc is well sharpened to cut the soil. The amount of concavity varies with the diameter of the disc. The approximate values being 8 cm for 60 cm diameter disc and 16 cm for 95 cm diameter.
A few important terms connected with standard disc plough is explained below:
It is a circular, concave revolving steel plate used for cutting and inverting the soil.
ii. Disc Angle:
It is the angle at which the plane of the cutting edge of the disc is inclined to the direction of travel. Usually the disc angle of good plough varies between 42 to 45°.
iii. Tilt Angle:
It is the angle at which the plane of the cutting edge of the disc is inclined to a vertical line. The tilt angle varies from 15° to 25° for a good plough.
It is a device to remove soil that tends to stick to the working surface of disc.
It is the depth measured at the centre of the disc by placing its concave side on a flat surface.
vi. Draft of Disc Plough:
The disc plough is lighter in draft than the mouldboard plough, turning same volume of soil in similar conditions. In very hard soil, some extra weight is added to the wheel which increases the draft. The bearings and scrapers of the disc plough also affect the draft.
II. Vertical Disc Plough:
It is a plough which combines the principle of the regular disc plough and the disc harrow and is used for shallow working in the soil. This type of plough is also called Harrow plough or one way disc plough. Its action is intermediate between regular disc plough and disc harrow. It has a frame, wheel arrangement, depth adjusting devices same as regular disc plough, but the discs are fitted on a single shaft and turn as one unit like a gang of disc harrow.
The spacing between the discs may be 20 to 25 cm for regular tractor drawn harrow plough. The size of the disc varies from 50 to 65 cm, and the disc angle varies from 40° to 45°. Usually a seed box is also mounted as an attachment of the harrow plough which permits seeding of small grains. Since operating depths of these ploughs are shallow (8 to 10 cm) energy requirement per hectare is much less than standard disc ploughs.
Adjustment and Repairs of Ploughs:
In both standard disc plough and vertical disc plough, the width of cut may be changed by adjusting the angle between the frame and the land wheel axle to rotate the entire frame in a horizontal plane. The disc angle is also changed in this way. Disc angle of 40° to 45° gives the minimum draft for a given width of cut.
Different adjustments on disc plough affect the depth of cut, width of cut and pulverization of the soil in the manner given below:
i. Penetration is improved by increasing the disc angle.
ii. Penetration is improved by decreasing the tilt angle on standard disc plough.
iii. Penetration is improved by adding additional weights on the plough.
iv. Width of cut is adjusted by adjusting the angle between the land wheel axle and the frame.
Type # 4. Chisel Plough:
It is a plough used to cut through hard soils by means of a number of narrow tynes. It is used before using the regular plough. It is useful for breaking hard layers of soil just below the regular ploughing depth. This layer of soil which is called hard pan or plough sole is very tough and hard.
Type # 5. Sub Soiler:
It is a plough designed to penetrate the soil to depths more than those achieved during normal ploughing operation. Usually the plough depth may be 40 cm or more up to 100 cm. It helps in breaking up of hard pan helping to drain heavy soil, simulating deep rooted growth to help crops withstand in drought conditions and aeration of soil.
Type # 6. Rotary Plough:
It is a plough used to cut and pulverize soil by impact forces by means of a number of rotary tynes or knives which are mounted on a horizontal rotor. Rotary plough is also called as rotary tiller. It is suitable for shallow cultivation and weed control. The rotary tiller consists of a power driven shaft on which knives or tynes are mounted to cut the soil and the trash. Rotor has got several types of tyne, fitted on shaft having a speed of 200 to 300 rev/min. One of the main problems with this tiller is that tynes are bent or broken in hard ground.
For this reason, various shock resisting devices are used on rotary tillers. The knives are spaced along the axis of the rotor in staggered way round the periphery. As the rotor revolves, the knives cut the soil from the ground. The rotary tiller stirs the soil more than other implements. It is useful for distributing and mixing organic matter and other materials throughout the fields.
Rotavator (Tractor Mounted):
It is used for seed bed preparation, weed control, mixing of soil with crop residue and fertilizer and puddling of soil. It is operated by top shaft of the tractor, attached to the 3 point linkage. The depth can be controlled by linkage and hydraulic system. Safety guard is provided at the rear.
Rotating Auger Plough:
It is a plough with a short plough bottom followed with vertical rotors having blades.