Change in erosion potential of crops due to climate change

Erosion by water on arable land can be influenced by the farmer mainly by crop selection, cultivation and field management. This requires updated knowledge on the erosion potential of crops, the so-called C factor of the (Revised) Universal Soil Loss Equation. In order to assess how climate change has already altered the C factors, we analysed the effects of a modified crop development and rain erosivity. To this end, we combined more than 4.2 million phenological observations in Germany with the seasonal distribution of rain erosivity derived from contiguous rain radar measurements comprising about 7.7 million events. We then compared the recent C factors to those derived in the 1980s. Due to temperature increase, crops developed earlier and / or faster, which was particularly true for maize due to its C4 mode of photosynthesis; and rains were more erosive during the dormant season. Both had a strong impact on the C factors. In particular, the C factor of maize decreased while that of winter cereals tended to increase because these crops pass the winter period in a stage susceptible to erosion. In consequence, the differences among crops in their erosion potential decreased. Our findings strongly suggest that the winter period has to receive larger attention in soil conservation. Thus, the use of winter cover crops may become even more effective to control erosion.