Controlled (managed) drainage

Artificially constructed surface and sub-surface (mole & tile) drains are an intrinsic component of many productive farm systems with either poorly drained soil types or in shallow groundwater conditions across large areas of the Manawatū, Taranaki, Waikato and Southland regions of New Zealand. Artificial soil drainage helps to remove the excess soil water, improve soil aeration, and hence plant growth during wet periods. However, they could also act potentially as a critical flow pathway for losses of nutrients (e.g., nitrate) from the soil profile.

Controlled (managed) drainage practice aims to design and implement flexibility in operation of artificial constructed surface and sub-surface drainage systems. This is achieved by a drain flow control device at the drain’s outlet. Controlling (managing) the drain flows during spring and summer periods could potentially reduce the amount of drainage water and reduce its associated nutrient losses from drained farm paddocks to waterways.