Farm Power And Machinery (1+1)

Special purpose ploughs

Rotary tiller (Rotovator)

• The rotary cultivator is widely considered to be the most important tool as it provides fine degree of pulverization enabling the necessary rapid and intimate mixing of soil besides reduction in traction demanded by the tractor driving wheels due to the ability of the soil working blades to provide some forward thrust to the cultivating outfit.


Plate : 13.2 Rotavator

• The functional components include tynes, rotor, transmission system, universal joint, leveling board, shield, depth control arrangement, clutch and three point linkage connection.
  
• Rotary tiller is directly mounted to the tractor with the help of three point linkage.
  
• The power is transmitted from the tractor PTO (Power Take Off) shaft to a bevel gear box mounted on the top of the unit, through telescopic shaft and universal joint.
  
• From the bevel gear box the drive is further transmitted to a power shaft, chain and sprocket transmission system to the rotor.
  
• The tynes are fixed to the rotor and the rotor with tynes revolves in the same direction as the tractor wheels.
  
• The number of tynes varies from 28 - 54. A leveling board is attached to the rear side of the unit for leveling the tilled soil.
  
• A depth control lever with depth wheel provided on either side of the unit ensures proper depth control.
The following types of blades are used with the rotovator.

i. 'L' type blade - Works well in trashy conditions, they are more effective in cutting weeds and they do not pulverize the soil much.
ii. Twisted blade - Suitable for deep tillage in relatively clean ground, but clogging and wrapping of trashes on the tynes and shafts.
iii. Straight blade - Employed on mulches designed mainly for secondary tillage.
The benefits of the rotary tiller are effective pulverization of soil ensures good plant growth, stubble and roots are completely cut and mixed with the soil and proper ground levelling after the operation.


Chisel plough

• Chisel ploughs are used to break through and shatter compacted or otherwise impermeable soil layers.
• Deep tillage shatters compacted sub soil layers and aids in better infiltration and storage of rainwater in the crop root zone.
• The improved soil structure also results in better development of root system and the yield of crops and their drought tolerance is also improved.
• The functional component of the unit include reversible share, skids, beam, cross shaft and top link connection.
• Chisel plough consists of heavy chisel type tyne which is pulled through the soil normally at a depth greater than that at which conventional ploughing would be done and bursting up the underlying layers of soil without bringing the sub-soil to the surface.
• The tynes of the implement are sturdy and strong enough to withstand the stresses applied when they are working at depth where the soil conditions are hardened.
• The implement frame is also strongly constructed usually of box section steel to withstand the stresses applied.
• The chisel plough has a sturdy but light structure made of 3 mm thick hollow rectangular tubular mild steel sections.
• The share has a lift angle of 20 degree, width of 25 mm and a length of 150 mm.
• The implement is protected by a shear pin, which prevents damage from over loading.
• The implement could be used for deep tillage upto a depth of 40 cm.
• The coverage is 0.42 ha/hr when operated at a spacing of 1.5 m between rows.
The salient features of the unit are:

• The implement could be used for deep tillage upto a depth of 40 cm for bursting of the sub-soil hard pan, improving the drainage and aerating the soil.
• Reduces the bulk density of soil
• Two fold increase in hydraulic conductivity of sub-soil
• Conserves around 30 to 40% more soil moisture
• Roots proliferation is improved from 40 to 45%
• Easily operated by any 35 to 45 hp tractor


Fig. 13.3 Line diagram of chisel plough


Sub-Soil plough

• The function of the sub-soil plough also called sub soiler is to penetrate deeper than the conventional cultivation machinery and break up the layers of the soil, which have become compacted due to the movement of heavy machinery or as a result of continuous ploughing at a constant depth.
  
• These compacted areas prevent the natural drainage of the soil and also inhibit the passage of air and nutrients through the soil structure.
  
• The sub-soiler consists of heavier tyne than the chisel plough to break through impervious layer shattering the sub-soil to a depth of 45 to 75 cm and requires 60 to 100 hp to operate it. The line diagram of sub soiler is shown in Fig. 13.4.
  
• The advantages are same as that of chisel plough.


Fig. 13.4 Line diagram of Sub soiler