Disposable resources in the vegetation periods are usually insufficient for realization the intensive form of irrigation in small agricultural catchments in lowlands areas. Assurance of proper amount of water for agricultural use, with more and more competition of the others users, become a serious problem. The field investigations, carried out in Samotwór in years 1994-2008 in direction of rational water management, proved that due to application the suitable and a whole year's exploitation of weir on the main stream, the disposable soil water resources can be effectively increased. In order to assessment the effectiveness of realized damming up the water, the measurements of soil water reserves in characteristic layers were done on areas with differentiated water retention of soils and situated on drained fields and fields uncovered by draining system. The researches proved that proposed way of improvement the water balance in the catchment brings the measurable effects in profitable forming of soil water content. Applied method of retention of water allows on effective keeping the water after periods with "excess" (thaw, high precipitation) and using the water in "deficit" periods (without precipitation). The investigations also showed that the effectiveness of improvement of the soil retention was explicitly higher on ...
