Soil losses due to mechanized potato harvesting

Abstract

Soil loss due to crop harvesting (SLCH) is a soil erosion process that occurs during the harvest of crops such as sugar beet, potato, chicory root, carrot and black salsify. Soil adhering to these crops and loose soil are harvested and exported from the field together with these crops, which consequently leads to lowering of the soil profile. Some studies report on the intensities and determining factors of SLCH for sugar beet and chicory roots. Only few studies, however, tried to estimate SLCH values for potato and no studies were found that investigated the determining factors of SLCH for this crop, although potato is, from an areal point of view, the most important crop in Europe and the Russian Federation and the second most important crop in the world leading to SLCH. This study tried to fill this knowledge gap by conducting field measurements ( n = 51) on potato harvesting machines on 29 field plots located in central and northern Belgium, with soil textures ranging from loamy sand to silt loam. The main objectives of the study were to assess SLCH for potato and to get more insight into the factors determining the spatial and temporal variability in SLCH. As soil clods are sometimes selectively removed by people at the sorting table of the harvesting machine and as the processes leading to soil adhering to potatoes and to soil clods were expected to differ, total soil losses were divided into soil adhering to potatoes (adhering SLCH) and soil clods (loose SLCH). Total soil loss during potato harvest was on average 3.2 Mg ha −1 harvest −1 and ranged from 0.2 to 21.4 Mg ha −1 harvest −1. The presence of soil clods induces the largest variability in total SLCH as adhering SLCH varied only between 0.2 and 3.6 Mg ha −1 harvest −1. About half of the variability in adhering SLCH could be explained by soil moisture content at harvesting time, while loose and total SLCH appeared to increase by increasing content of clay or particles <16 μm ( R 2 = 0.27 for loose and ±0.40 for total SLCH). Loose and total SLCH intensities are thus more difficult to predict than adhering SLCH, which is attributed to complex clod formation and destruction processes. No good multiple regression equations could be found due to strong interaction amongst the independent variables. SLCH for potatoes appeared to be lower than for sugar beet and chicory root, which can be attributed to crop morphology and planting of potatoes in ridges.