Tertiary tillage

Objective

• To destroys soil structure by lowering the porosity and permeability of soil and to form a soil plow pan
• Reducing percolation rates and there by the loss of water

When

• One day before sowing or planting

Method of operation

• Involves puddling (tillage of flooded soil) and leveling
• Basal fertilizer is added simultaneously, and soil is puddled several times until the fertilizer is mixed to the soil well
• Puddling is followed by leveling to have a good seedbed suited for plant growth.

Important considerations

• Puddling is very efficient in clay soils and form deep cracks (15 to 20 cm deep) in the plow pan during soil drying period before land preparation
• Puddling reduces percolation rates of the soil, however, it consumes higher volume of water
• Leveling a field is a prerequisite for good water and crop management. When field is not leveled, water may stagnate in the depressions whereas higher parts may fall dry resulting unevenness in crop emergence, early growth, fertilizer distribution and increased weed populations
• Better land leveling facilitates efficient crop establishment and care, reduce the time and water required to irrigate the field and ensure more uniform distribution of water in the field.
• Keeping 1 day after levelling will facilitate downward migration of the fine clay particles and fill up the cracks and pores in the plow pan.
• As this consumes about 20-40% of the total water requirement of the crop, farmers in some rice growing areas shift from conventional to non-puddle land preparation methods (e.g. minimum or zero tillage)