Depth of ploughing
Depth of ploughing mainly depends on the effective root zone depth of the crops.
Generally, crops with tap root system require greater depth of ploughing, while fibrous and shallow rooted crops require shallow ploughing.
Tree crops are needed deeper soil ploughing whereas; field crops generally needed only shallow tillage.
Number of ploughing
The number of ploughing necessary to obtain a good tilth depends on soil type, weed problem and crop residues on the soil surface.
In heavy soils, more (3-5) number of ploughing is necessary, but, light soils require 1 to 3 ploughing to obtain good tilth of the soil.
When weed growth and plant residues are higher, more number of ploughing is necessary.