Effects of different crop rotations on soil erosion and nutrient losses under natural rainfall conditions in Western Lithuania

This paper presents water erosion data of three stationary series of field experiments (each analysing 10 land plots) on various steepness slopes with different soil texture of the hilly topography of Western Lithuania (Zemaiciai Upland). Six different erosion-preventive crop rotations (four field crop rotations and two perennial grasses for sward formation) were investigated. It was demonstrated that extent of water erosion depends on erosion-preventative capabilities of different crop rotations, slope gradient, soil texture and the amount of precipitations. According to the results of long-term experiments, the mean annual erosion rate under the grass-grain rotation decreased by 95.0% compared with crop rotation with black fallow. The annual soil loss (SL) due to water erosion in the crop rotation with bare fallow was estimated to be between 0.01 and 18.56 t ha(-1)yr(-1). Usage of long-term grass sward completely prevented soil erosion. Perennial grasses and grass-grain crop rotations also prevented soil erosion on slopes during rainstorm (41-65 mm of precipitation during the day). However, even grain-grass rotations could not completely prevent the water erosion on the 9 degrees-11 degrees slopes with light textured soils. SL rate in 5-year rotation was 1.64 and 1.41 t ha(-1)yr(-1), respectively. Soil water erosion and nutrient losses are effectively inhibited by long-lived perennial grasses. Covering slopes with erosion-preventive sward forming perennial grasses in many cases prevented available potassium (K) and phosphorus (P) loss from inside the soil, however, the K and P losses resulting from runoff were 0.005-1.0 and 0.001-0.071 kg ha(-1), respectively.