Considerable masses of soil may be lost from arable land during the harvest of crops such as sugar beet, potato and chicory roots, as soil adhering to these crops, soil clods and rock fragments are exported from the field (together with the crop) to places such as headlands, farmsteads and crop-processing factories. This soil erosion process is referred to as soil losses due to crop harvesting (SLCH). These soil losses range from a few to tens of tonnes per hectare and per harvest and are thus the same order of magnitude as soil losses caused by water, wind or tillage erosion. However, only a few studies have incorporated SLCH as a soil erosion process. We investigated the variability of soil losses due to sugar beet harvesting at the field plot scale and the importance of controlling factors related to soil, agronomic practices and crop characteristics. Twenty-six field parcels, distributed over the Belgian sugar beet growing area, were sampled during the harvesting seasons 2002, 2003 and 2004. Soil losses ranged between 1 and 30 Mg ha−1 harvest−1 with an average of 4 Mg ha−1 harvest−1. Gravimetric soil moisture content at harvest was by far the most important controlling factor and was positively and exponentially related to SLCH. Differences in SLCH between harvesting seasons could not be explained by the factors investigated in this study, which indicates that other factors also play a role in SLCH variability.