Malfunctions of Finnish subsurface drainage

In Finland underdrainage malfunctions, either permanent or temporarly appear in about 5 % of the arable land. The reasons behind the malfunctions are in most cases relayed to the compaction of the topsoil and to such risks due to the topography, location, and peat soils that are difficult to drain, iron ochre and tendency of siltation which cannot be solved in a underdrainage project of average capital costs.