Spłukiwanie gleby na użytkowanych rolniczo stokach pogórskich w latach hydrologicznych 2007-2008 w łazach (Pogórze Wiśnickie)

The paper presents the results of slopewash studies carried out in hydrological years 2007-2008 on 7 runoff plots located within the marginal part of the Carpathian Foothills near the Research Station of the Institute of Geography and Spatial Management in Łazy. All the plots were 2 m wide. Four of them were 22.1 m long while the remaining three were 11.1, 5.5 and 2.8 m in length. All the plots were closed with 2 m Gerlach troughs. Eroded material was collected in tanks placed by every plot, while runoff was registered by means of lymnigraphs. The inclination of the plots' surface was 8°. Studies were carried on silty pseudogley soil (Stagnic Luvisols). Precipitation totals amounted to 814, l mm (2007) and 585,3 mm (2008) and these values significantly ditfered from the mean precipitation total for 1987-2008 hydrological years (661,5 mm). In 2007 the rainfall erosivity factor (EI₃₀) was 1628.9 MJ mm ha⁻¹h⁻¹ and turned out to be almost two times as much as it was for 2008 (667.0 MJ mm ha⁻¹h⁻¹). In the summer halfyear of 2007 hydrological year there were 13 slopewash events whereas in 2008 there were none. Mean annual soil erodibility [K] reached the value of 0.0377 Mg ha h MJ⁻¹mm⁻¹ha⁻¹, which is significantly lower than the value calculated on the basis of the USLE model (0.0738). Runoff varied considerably in the summer half-year. Maximum values of the runoff coefficient amounted to 39.2% for the potato, 34.2% for the fallow land, 16.3% for the winter wheat and 12.0% for the meadow. Mean annual slopewash values amounted to 31.4 kg ha⁻¹ for winter wheat, 41.9 kg ha⁻¹ for meadow, 43,396.0 kg ha⁻¹ for potato and 47,340.2 kg ha⁻¹ for fallow. The C factor value for the whole vegetation period of the potato was 0.92, and 0.0008 for the winter wheat.*