Deep Ploughing
One foot of surface soil over one hectare of land area approximately weighs about 5000 tonnes.
Therefore, to plough deeper, enormous amount of energy is required.
In western countries, deep ploughing of 50 cm depth for rainfed conditions and 70 cm for irrigated conditions is practiced.
Ploughing of 5-6 cm depth is classified as shallow, 15-20 cm depth as medium deep and 25-30 cm depth as deep ploughing.
Deep tillage is necessary for tap rooted crop and perennial crops, while, moderate deep tillage is preferred for fibrous rooted crops like maize and sorghum.
Deep ploughing results large sized clods, which are scorched by the hot sun when it is carried out in summer.