Tillage erosion causes substantial soil redistribution that can exceed water erosion especially in hummocky landscapes under highly mechanized large field agriculture. Consequently, truncated soil profiles can be found on hill shoulders and top slopes, whereas colluvial material is accumulated at footslopes, in depressions, and along downslope field borders. We tested the hypothesis that soil erosion substantially affects in‐field patterns of the enhanced vegetation index (EVI) of different crop types on landscape scale. The interrelation between the EVI (RAPIDEYE satellite data; 5 m spatial resolution) as a proxy for crop biomass and modeled total soil erosion (tillage and water erosion modeled using SPEROS‐C) was analyzed for the Quillow catchment (size: 196 km2) in Northeast Germany in a wet versus normal year for four crop types (winter wheat, maize, winter rapeseed, winter barley). Our findings clearly indicate that eroded areas had the lowest EVI values, while the highest EVI values were found in depositional areas. The differences in the EVI between erosional and depositional sites are more pronounced in the analyzed normal year. The net effect of total erosion on the EVI compared to areas without pronounced erosion or deposition ranged from −10.2% for maize in the normal year to +3.7% for winter barley in the wet year. Tillage erosion has been identified as an important driver of soil degradation affecting in‐field crop biomass patterns in a hummocky ground moraine landscape. While soil erosion estimates are to be made, more attention should be given toward tillage erosion.
Soils used for crop production cover 15.5 million km 2 and almost all have been tilled at some point in their history. However, how the changes in soil depth and soil properties associated with tillage affect crop yields is unclear. Here, we show that tillage on slopes thins soils and reduces wheat and maize yields. At the landscape scale, tillage erosion gradually reduces crop yields as the duration and intensity of tillage increase. Over the next fifty to 100 years, the overall yields are likely to further decline as modern mechanized agriculture accelerates the process of tillage erosion compared to centuries of non-mechanized tillage. Arresting this downward trend will require more widespread adoption of no-tillage practices and avoidance of downslope cultivation. The downward pressure on landscape-scale yields due to tillage erosion is expected to be amplified by climate change-induced increases in dry spells during crop growth.
Tillage erosion is a widely underestimated process initiating soil degradation especially in case of large agricultural fields located in rolling topography. It is often assumed that, conservation, non-inversion tillage causes less tillage erosion than conventional inversion tillage. In this study, tillage erosion was determined on three paired plots comparing non-inversion chisel versus inversion mouldboard tillage. The experiments were performed at three sites in Northeast Germany with gentle, moderate, and steep slope, while tillage depth (0.25 m) and speed (≈ 6 km h−1) were kept constant during all experiments. The results indicate that non-inversion tillage produces significantly more soil movement compared to inversion tillage. The soil translocation distance was by a factor of 1.3–2.1 larger in case of chisel tillage. The largest difference in translocation distance and tillage transport coefficient (ktil) was found on the gentle slope exhibiting the lowest soil cohesion. Our results together with an evaluation of ktil values derived from literature and standardised for 0.25 m tillage depth contradict the general assumption that non-inversion tillage reduces tillage erosion. In tillage erosion dominated areas, non-inversion tillage applied with high tillage speed and depth potentially increases tillage erosion and fails its purpose to serve as soil conservation measure.
<p>The young moraine landscape of North-East Germany is highly prone to tillage-dominated soil erosion processes due to highly mechanised farming in a rolling topography. The corresponding soil redistribution pattern highly influences crop biomass production and soil organic carbon (SOC) dynamics. The aims of the study are to understand the effect of soil redistribution processes on SOC dynamics like dynamic replacement and efficient SOC burial. Therefore, an updated version of the spatially explicit soil redistribution and carbon turnover model SPEROS-C was applied for a large-scale (200 km&#178;) simulation of lateral soil and SOC redistribution and vertical SOC turnover (spatial and vertical resolution 5 m x 5 m and 1 m soil depth, respectively). A sensitivity analysis was applied to identify the dominant modulators of SOC in the modelling approach (carbon input by roots, manure, and residues, decomposition of SOC, etc.). Uncertainties in model structure, process parameterisation, and input data are analysed with the GLUE approach (Generalized Likelihood Uncertainty Estimation). This approach is also used to estimate regional model parameters (e.g. SOC turnover rates, crop-specific root length density distribution, C input by aboveground biomass, manure, residues, etc.) to allow landscape-scale estimations of soil redistribution and accompanied C balance and hence, if this leads to a sink or source of CO<sub>2</sub>.</p>
<p>Hummocky landscapes under intensive arable use are substantially affected by erosion processes. Data from the Quillow catchment (size: 196 km<sup>2</sup>; mean annual precipitation: 500 mm) in North-East Germany are used to estimate landscape-scale water and tillage erosion with the model SPEROS-C. Recent results show that tillage erosion causes substantial soil redistribution that can distinctively exceed water erosion. In consequence, truncated soil profiles can be found on hilltops and steep slopes, whereas colluvial material is accumulated in depressions and along downslope field boarders. The resulting spatial variability of soil types with different properties and conditions is known to influence crop growth and leads to a highly variable biomass pattern in hummocky landscapes under highly mechanised arable cultivation.</p><p>The main goal of our study is to link tillage-induced erosion rates to landscape development at centennial time scales. By modelling the development of the hummocky moraine landscape of North-Eastern Germany, we explain the spatial distribution of the current soil erosion state. Furthermore, the soil erosion induced impact on crop biomass patterns and the redistribution of soil organic carbon since the beginning of human land use in this area is assessed. To address this goal, a new model component is implemented into SPEROS-C that iteratively rejuvenates topography backwards in time considering modelled erosion and deposition rates. Afterwards, modelling forward in time allows estimating carbon fluxes due to soil redistribution. Furthermore, the extent and location of truncated soils will be validated with historic aerial photographs at different time steps.</p><p>The benefits of implementing landscape development into SPEROS-C are that (i) an annual update of topography generates a more realistic soil erosion pattern, (ii) the current crop biomass pattern may be explained by erosion history, and (iii) estimates about the future development of crop yield patterns considering ongoing tillage practices can be drawn from a validated soil erosion and landscape development model.</p>
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