Disk harrow,Field cultivator

Secondary tillage implements

Disk harrow

Ø  Disc harrow is similar in shape as disc plow except they are smaller in size. Five or six disks are mounted on one axle to make a gang. The concavity of disk harrow is less as compared to disk plow, which results into less soil inversion and more pulverization.

Note: disc harrows are general purpose tillage tools as their 2 passes are just equivalent to 5 passes of tine cultivator

Uses:

Ø  It is used after plowing to cut up vegetative matter that may be on the surface, such as stalks, cotton stalks and weeds and to pulverize the soil.

Ø  It is used after plowing to pulverize the soil to put in better tilth for the reception of the seed.

Ø  It is used for cultivating of crops.

Ø  It is used for summer fallowing (ploughed but left unsown)

Ø  When seed are broadcasted it is used to cover them.

Types of disk harrow

Ø  The gangs of disk harrow may be arranged to form following types.

Ø  Single acting disk harrow

Ø  Double-acting disk harrow

Ø  Off –set disk harrow

Single acting disk harrow:

Ø  It consist of two sets of gangs of disks (one set to the left and other to the right).

Ø  The left hand gangs will throw soil to the left and right hand gang will throw soil to the right i.e in opposite direction

Ø  It leaves the field in an uneven condition.

Double acting disk harrow

Ø  It consist of front and rear gangs of disks

Ø  The implement will pulverize the soil better and leave the field almost even.

Off –set disk harrow

Ø  It consist of two gangs of disks, off-set from line of pull.

Ø  The front gang throws the soil to the right and the rear gang to the left.

Ø  This type of harrow can be used in gardens with low hanging branches of trees.

Ø  It leaves the soil even

Construction of disk harrow

Ø  The size of disk varies from 16-24 inches (40-60cm)

Ø  The thickness of disk is about 0.6cm

Ø  Distance between the disks is upto 25cm

Ø  The disks are mounted on tubular shaft

Field cultivator/narrow tine cultivator

Important features

Ø  It is just like chisel plow except that it is light in construction

Ø  It goes to a shallow depth

Ø  It breaks clods and pulverize the soil

Ø  If narrows tines are used, the soil between the tines is skipped, therefore a greater number of operations are required.

Ø  This implement dose not invert the soil

Ø  Greater number of tines (from 9-17) can be used with field cultivator depending upon size of cultivator.

These are classified into two categories

Spring tine cultivators

Sweep tine cultivators

Spring tine cultivator (these are preferred as they absorb shocks when hit an obstruction)

Ø  The depth of operation may be altered by;

Ø  Changing the position of shovel on the tines by raising or lowering it

Ø  Changing the pitch by means of the top link (in case of mounted cultivator)

Ø  Using the land wheel

Ø  Using the hydraulic system of the tractor

Sweep cultivator

Important features:

Ø  It is just like a narrow tine cultivator but instead of narrow tines, sweep shovels are used.

Ø  With the use of sweep shovels, no soil is skipped

Ø  Other features are the same as those of narrow tine cultivator

Ø  Note:

Ø  Narrow tine cultivator and sweep tine cultivator are used for secondary tillage as well as for intercultural operation.