Evaluation of the influence of cultivation period on soil redistribution in northeastern China using magnetic susceptibility

- The magnetic susceptibility values increased from the upperslopes to lowerslopes on all selected slopes.
- The longer the cultivation time, the larger the difference of magnetic susceptibility between upperslopes and lowerslopes.
- The soil loss of 110-year slope was about two times higher than that of 30-year slope at the middleslope and lowerslope.

Magnetic susceptibility has been shown to be a reliable, economic and rapid method for tracking soil redistribution; however, more case studies are necessary to verify the link between soil movement and magnetic susceptibility. In this study, we sought to evaluate soil redistribution in northeastern China using magnetic susceptibility on the basis of data collected from croplands with different cultivation periods. The results showed that the magnetic susceptibility values, whether low-frequency magnetic susceptibility (χlf) or frequency-dependent magnetic susceptibility (χfd), were markedly different between forestland and cropland, with larger differences for longer cultivation periods. The magnetic susceptibility increased dramatically in topsoils on forest slope, whereas the difference in magnetic susceptibility between topsoils and subsoils decreased in cropland as the cultivation period increased. The magnetic susceptibility values varied significantly across sites on a given slope, increasing gradually from the upperslope to the lowerslope, regardless of whether the slope was forestland or cropland. Longer cultivation periods resulted in larger differences between the upperslopes and lowerslopes which were particularly notable when the cultivation period was longer than 50 years. For middleslopes and lowerslopes, the soil loss of an 110-year cultivated slope was approximately two times higher than that of a 30-year cultivated slope. These findings suggest that the use of magnetic susceptibility is feasible for tracking soil redistribution and soil loss.