Is soil loss due to crop harvesting the most disregarded soil erosion process? A review of harvest erosion

While water and wind erosion are part of intensive research activities all over the world, soil loss due to crop harvesting (SLCH) is rarely acknowledged. SLCH occurs in tuber and root crops, which were cultivated on at least 1.1 million km2 worldwide in 2019. Thus, 8.4% of arable soils were affected by this kind of soil loss which can reach erosion rates of 22 Mg ha−1 harvest−1. Although these erosion rates are as high as for water and wind erosion, there are only 27 scientific references available that focus on SLCH. Hence, the relationship between possible environmental degradation and perception in science appears to be ambivalent. The aim of this review is to raise awareness of SLCH and harvest erosion. To achieve this aim, firstly the current state of knowledge on SLCH is summarized based on peer reviewed and international references. A special focus is on the rates of SLCH, on available regression equations to calculate the soil losses by harvest and on the environmental effects. Secondly, important research gaps and necessary research activities are identified. It becomes apparent that (i) new data is required which considers developments in harvest techniques and soil management, (ii) data from North America, South America and Oceania is urgently needed as no references for these regions are available yet, (iii) models to predict SLCH are necessary and (iv) research is required on the fate of the adhering soil within the landscape and on its environmental effects.