Soil loss due to sugar beet harvesting is an underestimated but significant soil erosion process in mechanized agricultural systems.

Abstract

Soil loss due to crop harvesting (SLCH) is a globally occurring, but underestimated process that contributes to soil degradation, adversely affecting soil functionality and fertility. In northern Europe, sugar beets play a crucial role for SLCH due to their high production rates, yet there is a lack of research in commercial mechanized farming of sugar beets. The aim of this study is to measure SLCH for sugar beets using typical commercial harvesters and identify relationships to crop and soil variables. Therefore, sugar beets and soil samples were collected for 14 sampling sites between 2018 and 2020 in Northern Germany. The results show that SLCH is in average 0.064 kg per kg sugar beet (SLCHspec), which corresponds to a loss of 5.7 Mg ha-1 harvest-1 (SLCHcrop). These numbers are higher than former comparable studies and 83.9 % higher than SLCH estimates by sugar beet factories. In addition, we found that i) SLCH considerably varies among years, fields, but also within fields, ii) the most influential drivers for SLCH are soil water content and clay content, iii) soil properties impact SLCH differently in dependence to soil water content, iv) SLCH of sugar beets can lead to significant nutrient and soil organic carbon losses. Thus, the results underline that SLCH is an important and underestimated determinant of soil erosion processes, which urgently needs to be considered in models and estimates additionally to concurrent processes like water, wind and tillage erosion. This is important for the adaptation of soil conservation measures in order to reduce ongoing soil degradation, especially in highly mechanized agriculture.