Magnetic susceptibility characteristics of surface soils in the Xilingele grassland and their implication for soil redistribution in wind-dominated landscapes: A preliminary study

Abstract

Wind erosion processes in the typical temperate Xilingele grassland of North China result in significant regional surface soil fine particle and carbon loss. They increasingly restrict local grass industry sustainable production and grassland ecosystem protection. It is challenging to link wind erosion and deposition at landscape scale using classical field monitoring or the expensive fallout environmental radionuclides tracing techniques. The low-cost but efficient magnetic susceptibility (MS) technique has been successfully demonstrated to have great potential to trace soil water erosion processes and patterns at large spatial and temporal scales. However, so far soil wind erosion research using MS technique has not been reported. This study had a trial to determine the variations of soil magnetic susceptibility on relative flat grassland by a grid soil sampling and to establish the relationship between wind erosion parameters and variations of MS in surface soils. 160 grid sampling sites were spaced at an interval of 400m across a study transect with 12.8km long and 1.6km wide. 319 soil samples were collected from the surface soils (0–1cm and 1–6cm layers). Grazing intensity of the sampling sites were investigated, and the samples were measured for mass-specific low-frequency magnetic susceptibility (χlf), absolute frequency-dependent magnetic susceptibility (χfd), percentage frequency-dependent magnetic susceptibility (χfd%), soil grain size and organic carbon concentrations. The results showed that the χlf, χfd and χfd% values in surface soils ranged from 30.0 to 97.8×10−8m3kg−1, 1.2 to 6.1×10−8m3kg−1 and from 3.2 to 8.0%, respectively. The variations of soil χlf values were closely related to grazing intensity, soil grain size and organic carbon concentrations, suggesting that soil erosion processes were very sensitive to soil properties. Moreover, the MS parameters (χlf, χfd%) were positively correlated with the soil erosion rates and negatively correlated with the dust deposition rates, indicating that MS parameters could potentially identify the erosion and dust deposition stages of wind dominated erosion processes in semi-arid grassland, respectively. These preliminary experimental results implied that magnetic susceptibility signals in surface soils will hopefully serve as a useful tool in the accuracy assessment of wind dominated erosion and deposition in the temperate grassland regions.