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Tillage erosion affects crop yields and carbon balance in hummocky landscapes

Subject Area Soil Sciences
Physical Geography
Term from 2019 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 422576233
 
Final Report Year 2024

Final Report Abstract

Soil erosion in arable landscapes poses a substantial threat to soil health and therefore often has a negative impact on a wide range of ecosystem services. While soil erosion caused by water (and in some cases wind) is relatively well studied, there are still large gaps in our knowledge of erosion caused by soil tillage. The magnitude of both types of erosion is comparable; in areas with low rainfall erosivity, tillage erosion can even be the dominant process. The aim of the project was to quantify the influence of tillage erosion on the yields of important agricultural crops and its feedback effects on the C cycle. The central hypothesis that increasing tillage erosion increases both field - scale yield heterogeneity - with a simultaneous decrease in mean yields per unit area - and landscape-scale C storage in soils was tested in the hummocky ground moraine landscape of NE Germany. The test region of the Quillow catchment was selected because it is characterized by a high degree of agricultural mechanization and low precipitation (with frequent dry spells) and thus by a high climate sensitivity of agricultural production. The significance of tillage erosion for the extent and heterogeneity of biomass production, C input and soil carbon storage was largely verified. Particularly in dry years, long-term tillage erosion leads to significant landscape-scale yield losses, which can be expected more frequently under climate change conditions. In general, soil displacement represents a soil carbon sink in the area. In addition, there were a number of highly exciting results. (i) The patterns of soil properties in the region are dominated by tillage erosion. (ii) Erosion-deposition patterns lead to a larger spatial differentiation of aboveground C input in dry compared to wet years. (iii) The above-ground C input has decreased over the last 100 years depending on the location (erosion zones < deposition areas) due to breeding. In the case of below-ground C input (root system), on the other hand, there is no recognizable cultivar effect, but there is an influence of the erosion state. (iv) In order to illustrate the effect of tillage erosion on biomass patterns, it was not sufficient to consider only the period since the increasing mechanization of agriculture, but also the land use of the last 1000 years. (v) Reduced tillage to protect against water erosion can lead to a significant increase in tillage erosion. To summarize, the project results underline the great importance of tillage erosion for soil-related ecosystem services, in this case biomass production and carbon storage. This should be considered when optimizing soil protection measures in the future.

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