The study attempts to assess drainage efficiency based on the time which is needed to reach the minimum dehydration standard. Investigations were conducted during the hydrological years 2000–2002 within an experimental object located in the Central Sudetes on drained arable soils. The level of groundwater was measured in selected pipe drainage sections with a normative or enlarged spacing. An analysis of the results showed that pipe drainage efficiently decreased the groundwater level in the period preceding spring field work, even in wet years, for both the normative and enlarged spacing.

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