Rotation Effects of Potato, Maize, and Winter Wheat on Soil Erosion by Water

The effects of cultivating different crops or applying different management practices on water erosion have been widely evaluated in plot or field experiments. While these experiments have focused on the direct effects of a certain crop, there is comparably little information on how crops influence soil loss during the following years. Our objectives were to evaluate the extent to which water erosion differs between potato (Solanum tuberosumL.) and maize (Zea maysL.), and how these crops influence soil loss of a following winter wheat (Triticum aestivumL.) crop. Soil erosion was measured in four small neighboring watersheds (0.8–4.2 ha in size) during 198 rainfall–runoff events (1994–2001). Each watershed included one field with a crop rotation of winter wheat, potato, winter wheat, and maize. This rotation was shifted by 1 yr for each field, and hence a comparison between the fields as well as a comparison over two crop rotations was possible. Runoff and soil loss from potato and maize differed only slightly because the better protection by cover during maize years was compensated by a better protection by contouring with potato ridges. Both effects were adequately described by the cover management and support practice (C and P) factors of the Revised Universal Soil Loss Equation. A clear difference in soil loss depending on the preceding crop occurred in the succeeding winter wheat fields. Especially in October, November, and February, soil loss after the potato crop was significantly higher. This could be explained by little residue cover, disintegration of large aggregates, and low stability of small aggregates following the potato crop. Carryover effects should be taken into account, optimizing crop rotations with respect to soil conservation. Moreover, they are highly relevant for modeling of water erosion from agricultural areas.