Pits
All sensors and sample collectors are installed in the walls of seven pits dug in the catchment. The pits were selected to represent different soil depths in the catchment and named according to the soil depth in cm. Pits 50, 70, 100, 130 and 160 are located in catchment I, and pits 60 and 80 in catchment II. The pits were excavated layer by layer and separate soil layers of each pit were stored in containers while the instrument installation and soil sampling was done. The hydraulic conductivity of the soil was measured with an infltrometer after removing one morphological layer (5-10 cm). The depths of each layer were measured from several points of the wall of the pit and the soil colour was determined. Samples for determination of bulk density, water retention curve, particle size analysis, carbon, nitrogen, extractable iron and aluminum and exchangeable cation contents were taken from five different locations of each layer of the pits. Similar samples from the weir were also taken.
After sampling and instrument installation the soil was returned to the pit in the same order as it was taken out, thus minimizing the mixing of different podzolic horizons of soil. Before filling the pits, the weight of stones (> 2 cm) was measured.
Instrumentation in pits was renewed during 2011 and 2012.
Four deepest pits 80, 100, 130 and 160 were renovated and a new pit 90 was established near phototower 3 during 2022-2023.