Definition - What does Hardpan mean?
Hardpan is an impermeable compact layer of clayey soil found below the top soil. Hardpans can be formed due to drought or by calcium carbonate, dissolved silica and iron oxide deposits that act as binding agents and fuse the soil particles together. It can also happen by human acts, such as repeated plowing, improper watering, continuous heavy traffic and compaction. If hardpan exists in areas where pipelines have to be installed, trenchless methods such as directional drilling, impact moling and direct pipe can be used to bore through the deposit.
Trenchlesspedia explains Hardpan
Much of the hardpan deposit exists at a short depth from the top soil. These hardpans reduce the useful soil depth and can lead to waterlogging during heavy rainfall. Farmers who use chemical fertilizers encounter this problem because the chemicals destroy the mycelium essential for healthy root growth. Private properties encounter hardpan issues due to compaction activities carried out during house construction and due to insufficient watering.
To break the hardpan formation, soil stirring, soil ripping and earthing are essential. Hardpan can be identified by observation and mechanical means. Waterlogging after rainfall, difficult penetration of tilling equipment, uneven growth of crops and horizontal root growth after a certain depth are some of the indicators.