The influence of working of the unused sub-irrigation system on air-water conditions of peat-moorsh soil is presented in this paper. Measurements of moisture content, ground and open water levels were carried out in period July-September 2013. Top layers of the analyzed peat soil were characterised by wide range of moisture content changes. The analyzed part of the sub-irrigation system ditches and the river drain flowing through the analysed plot showed the drainage character. The ground water levels on the plot used as a meadow were observed higher to the soil surface than in case of abandoned part of peatland situated behind the river. ...