Subsoiling is a deep tillage practice that involves breaking up and loosening the compacted layers of soil found below the normal ploughing depth, typically between 12 and 24 inches beneath the surface. This compacted layer, often called a hardpan or plough pan, restricts root growth, water infiltration, and drainage.

A specialised implement called a subsoiler or chisel plough is used; it features long, narrow shanks that penetrate deep into the soil without inverting it, unlike conventional ploughing.

Key benefits of subsoiling include:

• Improved water penetration and reduced surface runoff

• Enhanced root development for deeper moisture and nutrient access

• Better aeration of the deeper soil profile

• Increased crop yields, especially in compacted fields

Subsoiling is typically performed during dry soil conditions so the shanks can shatter the hardpan effectively rather than just displacing it. It is commonly practised in agricultural fields subjected to heavy machinery traffic, which accelerates compaction over time.