An impact of drainage system on soil water conditions at Lidzbark Warminski experimental site

The aim of this study is to evaluate the impact of a drainage system on soil water conditions in a loam soil compared to that in undrained clay loam soil under various topographic conditions. The soils are located on a sloping area at Lidzbark Warminski experimental site (Poland) with well surface water outflow conditions and used as a pasture. The loam soil was drained with ceramic drainage pipes with an average drain spacing of 14 m and an average drain depth of 0.9 m, while the clay loam soil profile was not drained. The research was conducted during the period from 1999 to 2005. Ground water level as well as soil moisture content were measured monthly for both soil profiles. Meteorological conditions (precipitation and data for calculation of reference evapotranspiration) were also recorded. The results obtained show that in the loam soil (drained site) water level is on average 42 cm higher compared to that in the clay loam soil (not drained site). In both soils the amplitude of the ground water level changes was relatively high and exceeds 300 cm. In the drained loam soil, the water level position exceeded the depth of the drainage system in very wet, wet and average years. Under wet meteorological conditions the increase in ground water levels in the clay loam soil was slower than in the loam soil.