The Effect of Land use Type and Slope Degree on Phosphorous and Potassium Losses in Runoff Using Rainfall Simulators (Case study: Kakasharaf Watershed Basin, Lorestan)

Water erosion causes serious damage to all natural ecosystems, including the soil and nutrients loss (Collman et al., 2010). Nutrients loss and soil fertility reduction are the most important effects of soil erosion, which increase the fertility of soils in downward of the basin and cause contamination of surface and underground water (Telles et al., 2013). Soil loss is a serious problem in developing countries and has been a source of concern (Wolancho, 2012). Phosphorus and potassium are important elements in agricultural products. Each of the mentioned elements has especial behavior in transferring by runoff. Potassium is very mobile in comparison with phosphorus, so it is easily displaced by water from the runoff process. Despite numerous studies done in the world regarding the loss of elements in runoff and sediment, there is no accurate information in this regard in Iran. In Lorestan Province, due to the lack of attention to land suitability in land uses, basins are severely subject to erosion and soil degradation. Therefore, the present study was conducted to investigate the effects of slope and type of land use on the loss of potassium and phosphorus in runoff in Kakasharaf Basin in Lorestan province.