1. DISC HARROWS
The objective of cultivation is to prepare a seedbed from the furrows left by ploughing. The depth and fineness of a seedbed depends on the crop that is to be planted. Potatoes need a deep, fairly rough seedbed, whereas small seeds like most vegetables require a shallow very fine tilth on the seedbed. Cultivating implements are designed to break up the plough furrow, break down the clods and level the land so that seeds can be sown or seedlings planted out. Heavy implements like disc harrows produce a deep coarse tilth, while rollers, drag harrows and tine cultivators work on the surface to produce a fine shallow tilth. Disc harrows break up the large clods by cutting and grinding the soil and their effect is increased by setting the routs of discs at different angles to each other. They are also used for cutting up surface trash, and on light sandy soils can be used to produce a seedbed on arable land without the need for ploughing.
Figure 1: A Disc Harrow
Figure 2: A Disc Harrow working the soil
Figure 3: Disc harrows in harvested wheat field ready to disc
Figure 4: A Heavy Tine Cultivator for deep cultivation
Figure 5: Multi-tine Cultivators for light cultivation and working down a fine seedbed
Figure 6: shows cultivators being used for mechanical weeding between rows of growing crops. Thisis done to kill weeds, aerate the soil and break up any crust or cap on the soil surface.
Light Drag Harrows
These are used for the final cultivating operation before sowing the seed. They produce a fine seedbed and can cover a large area quickly.
Figure 7: A light drag harrow
The roller is used to break down clods on the soil surface and to consolidate the soil to preserve moisture. Consolidation of the soil surface to keep moisture in the soil is most important in both early and late ploughing.
Figure 8: A roller operation is taking place
Gang Rollers can be used to break up clods on the soil surface after discing. The rollers can be hitched, to give a wide cover or they can be hitched with one behind the other to give a narrow cover but better rolling.
Levelling machinery includes Land Planes and Grader Blades and is used for making farm roads, levelling the land before sowing crops, and making the beds required for flood irrigation. The machine shown below is a combination of a ridger and leveller and is making beds for sowing groundnut seeds.
Figure 9: A combination of a ridger and leveller
Figure 10: A tractor mounted Grader Blade which can be used to maintain farm roads, level offseedbeds and make flood irrigation beds.